Monday, 21 July 2014

Lesson 4: Aerobic and Anaerobic Digestion and Types of Decomposition

Lesson 4:
Aerobic and Anaerobic Digestion and
Types of Decomposition

In this lesson we will answer the following question:
  • Is aerobic and anaerobic digestion?
  • What occurs in each of these processes?
  • What are the three types of decomposition, and what occurs in each of these processes?

Reading Assignment
Read online lecture and Chapter 4 in textbook, Operation of Wastewater Treatment Plants, Vol. 1.

Microorganisms , like all living things, require food for growth . Biological sewage treatment consists of a step-by-step, continuous, sequenced attack on the organic compounds found in wastewater and upon which the microbes feed.
In the following sections we will look at the processes of aerobic and anaerobic digestion and the decomposition of waste in each process.

Aerobic Digestion
Aerobic digestion of waste is the natural biological degradation and purification process in which bacteria that thrive in oxygen-rich environments break down and digest the waste.
During oxidation process, pollutants are broken down into carbon dioxide (CO 2 ), water (H 2 O), nitrates, sulphates and biomass (microorganisms). By operating the oxygen supply with aerators, the process can be significantly accelerated. Of all the biological treatment methods, aerobic digestion is the most widespread process that is used throughout the world.

Biological and chemical oxygen demand
Aerobic bacteria demand oxygen to decompose dissolved pollutants. Large amounts of pollutants require large quantities of bacteria; therefore the demand for oxygen will be high.
The Biological Oxygen Demand (BOD) is a measure of the quantity of dissolved organic pollutants that can be removed in biological oxidation by the bacteria. It is expressed in mg/l.
The Chemical Oxygen Demand (COD) measures the quantity of dissolved organic pollutants than can be removed in chemical oxidation, by adding strong acids. It is expressed in mg/l.
The BOD/COD gives an indication of the fraction of pollutants in the wastewater that is biodegradable.

Advantages of Aerobic Digestion
Aerobic bacteria are very efficient in breaking down waste products. The result of this is; aerobic treatment usually yields better effluent quality that that obtained in anaerobic processes. The aerobic pathway also releases a substantial amount of energy. A portion is used by the microorganisms for synthesis and growth of new microorganisms.

Path of Aerobic Digestion

Aerobic Decomposition
A biological process, in which, organisms use available organic matter to support biological activity.  The process uses organic matter, nutrients, and dissolved oxygen, and produces stable solids, carbon dioxide, and more organisms.  The microorganisms which can only survive in aerobic conditions are known as aerobic organisms.  In sewer lines the sewage becomes anoxic if left for a few hours and becomes anaerobic if left for more than 1 1/2 days.  Anoxic organisms work well with aerobic and anaerobic organisms.  Facultative and anoxic are basically the same concept.

Anoxic Decomposition
A biological process in which a certain group of microorganisms use chemically combined oxygen such as that found in nitrite and nitrate.  These organisms consume organic matter to support life functions.  They use organic matter, combined oxygen from nitrate, and nutrients to produce nitrogen gas, carbon dioxide, stable solids and more organisms.

Anaerobic Digestion
Anaerobic digestion is a complex biochemical reaction carried out in a number of steps by several types of microorganisms that require little or no oxygen to live. During this process, a gas that is mainly composed of methane and carbon dioxide, also referred to as biogas, is produced. The amount of gas produced varies with the amount of organic waste fed to the digester and temperature influences the rate of decomposition and gas production.

Anaerobic digestion occurs in four steps:
•  Hydrolysis : Complex organic matter is decomposed into simple soluble organic molecules using water to split the chemical bonds between the substances.
•  Fermentation or Acidogenesis: The chemical decomposition of carbohydrates by enzymes, bacteria, yeasts, or molds in the absence of oxygen.
•  Acetogenesis: The fermentation products are converted into acetate, hydrogen and carbon dioxide by what are known as acetogenic bacteria.
•  Methanogenesis: Is formed from acetate and hydrogen/carbon dioxide by methanogenic bacteria.
The acetogenic bacteria grow in close association with the methanogenic bacteria during the fourth stage of the process. The reason for this is that the conversion of the fermentation products by the acetogens is thermodynamically only if the hydrogen concentration is kept sufficiently low. This requires a close relationship between both classes of bacteria.
The anaerobic process only takes place under strict anaerobic conditions. It requires specific adapted bio-solids and particular process conditions, which are considerably different from those needed for aerobic treatment.
Path of Anaerobic Digestion

Advantages of Anaerobic Digestion
Wastewater pollutants are transformed into methane, carbon dioxide and smaller amount of bio-solids. The biomass growth is much lower compared to those in the aerobic processes. They are also much more compact than the aerobic bio-solids.

Anaerobic Decomposition
A biological process, in which, decomposition of organic matter occurs without oxygen.  Two processes occur during anaerobic decomposition.  First, facultative acid forming bacteria use organic matter as a food source and produce volatile (organic) acids, gases such as carbon dioxide and hydrogen sulfide, stable solids and more facultative organisms.  Second, anaerobic methane formers use the volatile acids as a food source and produce methane gas, stable solids and more anaerobic methane formers.  The methane gas produced by the process is usable as a fuel.  The methane former works slower than the acid former, therefore the pH has to stay constant consistently, slightly basic, to optimize the creation of methane.  You need to constantly feed it sodium bicarbonate to keep it basic. 


The aerobic, anoxic, and anaerobic process helps prepare the waste for decomposition by attacking the organic compounds that in wastewater. In aerobic decomposition the only microorganisms that can survive are the aerobic organisms. In anoxic decomposition the microorganisms use chemically combined oxygen that is found in nitrite and nitrate. In this process the organisms consume the organic matter to help support their life functions. In the first stage of anaerobic decomposition, acid forming bacteria use the organic matter for food which produces volatile gases, acids and facultative organisms. Second stage methane formers use the volatile acids as a food source and that produces more gases. This gas can be used as fuel.

Answer the following questions and email your answers to
  1. What occurs in aerobic and anaerobic digestion?
  2. What do aerobic bacteria demand for decomposition of pollutants?
  3. How are BOD and COD measured?
  4. List two advantages of aerobic digestion?
  5. What is aerobic decomposition?
  6. What is anoxic decomposition?
  7. List the four steps in anaerobic digestion and explain each.
  8. List two advantages of anaerobic digestion.
  9. What is formed in the first and second stages of anaerobic decomposition?
  10. What must be feed in anaerobic decomposition to keep the pH constant?

Answer the questions for the Lesson 4 Quiz. When you have completed the quiz, you may email or fax it to your instructor. You may also take the quiz online and directly submit into the databas

Friday, 18 July 2014

Photosynthesis and the Reef Aquarium, Part I: Carbon Sources

Photosynthesis and the Reef Aquarium,
Part I: Carbon Sources

Photosynthesis is the process whereby organisms take in light energy and convert it into useful chemical energy. It is a critically important process in most reef aquaria, but one which most aquarists pay little attention to, aside from the recognized importance of having appropriate lighting. This article is the first in a series that looks at photosynthesis in reef aquaria from a chemical perspective. Such chemical issues, for example, include how organisms get the raw materials for photosynthesis, whether aquarists need to "supplement" those, how organisms eliminate the "waste" products of photosynthesis, what are the chemical implications of too much or too little light, how calcification in corals and clams relates to photosynthetic efficiency, what the biochemical machinery is for collecting light and converting it into energy, and how organisms have evolved these processes in relation to their natural habitats.
The answers to these questions can have an important bearing on husbandry practices in ways that reef aquarists might not have considered. In particular, topics covered in this article include whether the pH or alkalinity of an aquarium or a refugium might impact the rate of photosynthesis, and whether aquarists should consider the availability of carbon dioxide to photosynthesizing organisms.
The most simplified chemical equation describing photosynthesis is:
carbon dioxide + water + light à carbohydrate plus oxygen
or in a chemical formula:
CO2 + H2à CH2O + O2
This article deals primarily with the first reactant in this equation, carbon dioxide. The processes leading to the uptake of carbon dioxide by photosynthesizing marine organisms are an active area of research, with most of the relevant publications in this area being released only in the past five years. It turns out that the symbiotic dinoflagellates (zooxanthellae) inside corals and clams1 are a special case in terms of carbon dioxide acquisition due to the surrounding host animal, as well as the significant amount of calcification taking place in the same organism. Because photosynthesis and calcification may be chemically interrelated, the special aspects of photosynthesis in symbiotic and calcifying organisms will be detailed in a future article.
Freshwater aquarists caring for brightly-lit planted aquaria have long known the importance of CO2, and often add carbon dioxide directly to the aquarium water in one way or another to supply those tanks' substantial need for this material. Reef aquarists, on the other hand, might have just as much or more photosynthesis taking place, but rarely worry about adding carbon dioxide. Why? That's one of the topics to be detailed in subsequent sections of this article. The answer is not that seawater contains more CO2 than does freshwater, but rather that seawater contains other chemicals that can, in some cases, be used to supply carbon dioxide.
The contents of this article are:

Many organisms in a reef aquarium rely on photosynthesis to survive. These include diatoms, green hair algae, cyanobacteria, macroalgae, Tridacna clams and most corals and anemones that aquarists maintain. In the case of clams, corals and anemones, this photosynthesis is actually carried out by symbiotic organisms (zooxanthallae) that live within the tissue of the host animal. In every case, however, the cells that photosynthesize need to incorporate carbon dioxide somehow, and they excrete oxygen.
Sometimes obtaining adequate carbon dioxide is easy for photosynthesizing organisms, and sometimes it is difficult, requiring them to develop special mechanisms to obtain it rapidly enough. In order to understand how this happens in a reef aquarium, it is first necessary to understand what happens to carbon dioxide when it dissolves into seawater.
Carbon Dioxide in Seawater

Carbon dioxide is an interesting molecule. When it dissolves into water it can take a number of different forms. Even the rate at which it can move between some of these forms impacts how organisms must develop special mechanisms to be able to take up enough during rapid photosynthesis.
Carbon dioxide is present at about 350 ppm in normal air. It was lower in the past, and has been steadily rising for the past 100 years or so, largely due to the burning of fossil fuels. A liter of air weighs about 1.3 grams, so at 350 ppm carbon dioxide, that liter of air contains about 0.00046 grams (0.5 mg) of carbon dioxide. This very low amount, coupled with the kinetic issues (i.e., the slowness) of carbon dioxide's entry into seawater, explains why it is often difficult to keep reef aquarium water aerated enough to keep the pH from rising when processes such as photosynthesis or the addition oflimewater consume carbon dioxide.
When a gas phase carbon dioxide molecule enters water, it is initially hydrated to carbonic acid:
CO2 + H2à H2CO3
That hydration process is surprisingly slow because it's an actual chemical reaction, as shown schematically below:
The time for half of the CO2 molecules added to water to hydrate is on the order of 23 seconds. That rate is slow enough that many organisms have developed enzymes to speed it up. Carbonic anhydrase, for example, catalyzes the hydration and the reverse reaction (dehydration) to allow organisms to process carbon dioxide more rapidly. It is used by a wide array of organisms, from algae to people. In people, it is important in allowing carbon dioxide gas to be expelled from the lungs. Without it, the carbonic acid in the lung tissues would not convert rapidly enough to gaseous CO2 to permit it to be adequately expelled by breathing.
The carbonic acid that is formed when carbon dioxide hydrates can then very quickly equilibrate into the water's carbonate buffer system, converting into both bicarbonate and carbonate by releasing protons (H+):
The conversions between carbonic acid, bicarbonate and carbonate are much faster than the hydration of carbon dioxide and for most purposes can be considered instantaneous. Consequently, carbonic acid, bicarbonate and carbonate are in equilibrium with each other at any given point in time. The primary factor that determines the relative amount of each species at equilibrium in seawater is the pH, with asmall temperature effect as well.
In order to assess whether an organism requiring CO2 could benefit from any of the forms besides CO2itself, it is useful to understand how much of each is present in seawater. Seawater contains about 670 times more unhydrated carbon dioxide than the hydrated version (carbonic acid). At most pH values attained in a reef aquarium, however, bicarbonate is far more prevalent than carbon dioxide.
Using the known pKa values for carbonic acid and bicarbonate in seawater, we can proceed to determine exactly how much of each form is present in seawater as a function of pH. The relevant chemical equations and pKa values are:
CO2 + H2ßà HCO3- + H+      pKa = 5.85
HCO3-ßà CO3--+ H+      pKa = 8.92
These pKa values imply that seawater at pH 5.85 contains equal concentrations of carbon dioxide and bicarbonate, and that seawater at pH 8.92 contains equal concentrations of bicarbonate and carbonate. Figure 1 shows data calculated for all three species as a function of pH in seawater. From this graph, it is clear that if getting carbon dioxide itself is limiting at pH 8.2, it might be more efficient to get it from bicarbonate because so much more is present. In fact, roughly 200 times more bicarbonate than carbon dioxide is present in seawater at pH 8.2. In most reef aquaria the bicarbonate is present at between 2 and 4 mM (millimolar = meq/L), or about 122 to 244 mg/L bicarbonate. For comparison, carbon dioxide is much lower, on the order of 0.01 mM (0.5) mg/L at pH 8.2. Interestingly, that value of 0.5 mg/L for carbon dioxide in seawater is almost exactly the same as the concentration of carbon dioxide in air.
Figure 1. Relative fraction of carbon dioxide and carbonic acid (black), bicarbonate (white) and carbonate (red) in seawater as a function of pH.
Obtaining Carbon Dioxide as Carbon Dioxide: Passive Uptake

Carbon dioxide is able to cross cell membranes because it is a small uncharged molecule with reasonable solubility in organic materials. Consequently, organisms that take up carbon dioxide can do so passively (without spending any energy) and with no special mechanisms (such as proteins designed to speed up that process). Many marine algae and other organisms take up some measurable portion of the carbon dioxide that they incorporate during photosynthesis by this process.
In most cases, however, this process can account for only a portion of the demand for carbon dioxide. The rate at which carbon dioxide is used by rapidly photosynthesizing organisms is fast enough that organisms can deplete the carbon dioxide in the surrounding seawater faster than it can be replaced by diffusion and other transport mechanisms through the seawater. The depletion is readily observed by the pH in the near surface regions of these organisms, where the pH rises due to carbon dioxide loss. For this reason many marine organisms have developed other means of obtaining carbon dioxide, including processes involving bicarbonate.2
Freshwater algae, on the other hand, can sometimes obtain all of their required carbon dioxide by passive uptake.3 While a review of such literature is unnecessary in this article, I'll give one example. The freshwater chrysophyte alga, Mallomonas papillosa, has been shown to have none of the more sophisticated mechanisms for carbon dioxide uptake that are described later in this article, and it relies on simple passive uptake. For this reason it has been shown to photosynthesize most effectively where carbon dioxide concentrations are high, at pH 5-7.4
Obtaining Carbon Dioxide: Concentrating Mechanisms

As mentioned above, few marine organisms have been shown to rely solely on passive carbon dioxide uptake, but the carbon dioxide concentrating mechanisms are often unknown. As stated in a review article5 in 2005, marine diatoms fix more than 10 billion tons of carbon by photosynthesis each year, but "there are still a number of fundamental unresolved aspects of inorganic carbon assimilation by marine diatoms. It is not clear how the carbon-concentrating mechanism functions."
Obtaining Carbon Dioxide as Carbon Dioxide: Active Transport

Carbon dioxide can be actively transported across cell membranes by protein transporters. This process does not solve the problem of low levels of available carbon dioxide in the surrounding seawater, but it can ensure that uptake itself is not a limiting factor, and may be especially useful in environments where carbon dioxide is plentiful (implying low pH environments in seawater).
The two marine dinoflagellates, Amphidinium carterae Hulburt and Heterocapsa oceanica Stein, demonstrate active uptake of carbon dioxide (or carbonic acid), but not bicarbonate.6 Because this mechanism is fundamentally limited in its effectiveness, it has been speculated that these organisms may be CO2-limited in their natural environment.7
Two marine haptophytes, Isochrysis galbana Parke and Dicrateria inornata Parke, demonstrate active uptake of both carbon dioxide (or carbonic acid) and bicarbonate (described below).6,8
The marine diatom Skeletonema costatum9 has been shown to have little capability of using bicarbonate to obtain carbon dioxide. It does, however, show active uptake mechanisms for carbon dioxide, and this capability depends on light levels. In higher light levels, the diatom shows higher affinity for carbon dioxide. This capability can be attained within two hours of exposure to high light, and slowly fades over a period of about 10 hours when returned to low light levels (where less carbon dioxide uptake is required). Presumably, the organism is producing a carbon dioxide transport protein when light levels are high and carbon dioxide is needed in large amounts, and it halts that production (allowing the transporters to slowly decline in population) when they are not needed. High ambient levels of carbon dioxide also repress the expression of its high affinity for carbon dioxide uptake. Apparently, this diatom spends the energy to take up carbon dioxide actively only when it is actually necessary to do so, and relies on diffusion when it can.
Obtaining Carbon Dioxide from Bicarbonate: Carbonic Anhydrase

If an organism is to obtain carbon dioxide from bicarbonate, several potential processes are available, and different organisms take different approaches. In many cases, the exact mechanisms have not been established. It is much easier to show that bicarbonate is a source of carbon dioxide for marine organisms than to show exactly how they take it up. A bicarbonate ion, being charged and insoluble in organic phases, cannot readily diffuse across cell membranes, so other mechanisms are needed.
Such uncertainty of mechanism is the case for Ulva lactuca, for example. It has been shown to be able to photosynthesize when out of the water (say, exposed at low tide), taking up carbon dioxide directly, and also when in the water, taking up bicarbonate.10 But the exact mechanism of using bicarbonate to obtain carbon dioxide isn't known in this species.
One common way to use bicarbonate is for the cells exposed to the seawater to use extracellular carbonic anhydrase on their surfaces. As mentioned above, the enzyme carbonic anhydrase catalyzes the hydration and dehydration of carbon dioxide and carbonic acid, respectively. These organisms present this enzyme to the bicarbonate-rich seawater surrounding them. Because the bicarbonate is naturally in rapid equilibrium with carbonic acid, and the carbonic anhydrase keeps the carbonic acid in rapid equilibrium with unhydrated carbon dioxide, the bicarbonate is used as a ready pool to supply carbon dioxide to passively cross cell membranes and be taken up (shown schematically below).
The agarophyte Gracilaria lemaneiformis11 has been shown to take up carbon in this fashion. It has carbonic anhydrase both inside the organism and out. Inhibiting either of these types of carbonic anhydrase greatly decreases photosynthesis, but adding an anion transport inhibitor does not. Adding TRIS buffer to the extracellular fluid (seawater) also has no effect (the purpose of which is discussed in the following section relating to proton pumping as a possible mechanism).
Photosynthesis in this organism is greatly reduced as the pH is raised (73% reduction when going from pH 8.0 to 9.0), presumably because the bicarbonate's propensity to form carbonic acid is reduced at higher pH.
The brown alga, Hizikia fusiforme (Sargassaceae),12 from the South China Sea, has also been shown to exhibit carbonic anhydrase activity, both inside and out, and has been shown to be incapable of actively and directly transporting bicarbonate. Consequently, its carbon dioxide concentration likely operates by the mechanism shown above.
Two species of marine prymnesiophytes (Dicrateria inornata and Ochrosphaera neapolitana)13 have been shown, through the use of various carbonic anhydrase inhibitors, to use extracellular carbonic anhydrase to collect carbon dioxide from ambient bicarbonate. They also employ an energy dependent process for taking up carbon dioxide itself. Growth in high carbon dioxide environments represses the expression of carbonic anhydrase active in these species, but does not reduce the active uptake of carbon dioxide.
Obtaining Carbon Dioxide from Bicarbonate: Direct Uptake

An alternative way to obtain carbon dioxide via seawater bicarbonate is to take up the bicarbonate through protein transport mechanisms across the cell membranes, and then once inside the cells where it is needed, carbonic anhydrase converts it into carbon dioxide and hydroxide ion. The hydroxide is then pumped out, or H+ is pumped in, to achieve pH balance.
Transporting ions across cell membranes using protein transporters is a widespread mechanism whereby organisms can get needed ions across a membrane through which they do not normally diffuse. Some of these are active transporters, using chemical energy to "pull" ions out of the extracellular fluid (our push them out, as necessary), and other transporters simply allow specific ions to pass though from high concentration on one side to lower concentration on the other side.
The marine red alga Gracilaria conferta has been shown to have an active bicarbonate uptake mechanism.14 Three marine bloom-forming (red tide) dinoflagellates, Prorocentrum minimum,Heterocapsa triquetra and Ceratium lineatum,15 have been shown to take up bicarbonate directly. They show little carbonic anhydrase activity, yet bicarbonate accounts for approximately 80% of the carbon dioxide they use in photosynthesis. It is believed that these dinoflagellates are not carbon limited in photosynthesis due to their efficient direct bicarbonate uptake mechanisms.
The marine diatom Phaeodactylum tricornutum16 was found not only to have an active bicarbonate uptake mechanism, but the researchers further identified at least two different mechanisms. In particular, they showed that part of the uptake depended on the presence of extracellular potassium, and this part of the total carbon dioxide uptake was eliminated when potassium was missing from the medium. A second direct bicarbonate uptake mechanism was independent of potassium, indicating the presence of at least two different pathways for transporting bicarbonate into this organism.
Obtaining Carbon Dioxide from Bicarbonate: Proton Pumping

Another way to obtain carbon dioxide via seawater bicarbonate is to pump H+ out of the cells into the extracellular fluid (seawater near the cells) or into a special cavity where bicarbonate is present.17 This low pH causes the bicarbonate to become protonated to become carbonic acid. The carbonic acid can then transform into carbon dioxide, and pass across the cell membranes.
The seagrass Zostera noltii Hornem18 has been shown, for example, to use proton pumping to gather bicarbonate in the form of carbonic acid from the water. It contains no extracellular carbonic anhydrase, but rather uses ATP (adenosine triphosphate, the fundamental currency of chemical energy in most organisms) to drive the export of H+. Evidence for this mechanism is found by adding a buffer to the seawater (TRIS) without changing the pH. This buffer keeps the pH near the cell surface constant, counteracting the beneficial effect of the proton pumping in lowering pH and converting bicarbonate into carbonic acid. The simple presence of a non-absorbed buffer in the water can decrease the rate of photosynthesis in this organism by almost 80%.
Interestingly, those seagrass specimens acclimated to high light (where high rates of photosynthesis and consequent uptake of bicarbonate would be highest) showed the greatest ability to actively take up bicarbonate. In high light experiments, these previously high light-acclimated specimens were shown to be only light limited, while the shade-acclimated organisms were both light and carbon limited when put into high light.18 Other seagrass species (e.g., Z. mulleri and Z. marina) have been shown to have external carbonic anhydrase, and so may have different uptake mechanisms.18
Photosynthesis of Macroalgae as a Function of pH

One of the side effects of the necessity of taking up carbon dioxide to photosynthesize is that pH may affect the rate of photosynthesis, because the amount of carbon dioxide (as CO2 or H2CO3) in the water varies with pH. Assuming constant carbonate alkalinity, the effect is quite strong. A drop of 0.3 pH units implies a doubling of the carbon dioxide concentration. A reef aquarium at pH 8.5, for example, has one fourth the carbon dioxide of a reef aquarium at pH 7.9, assuming the carbonate alkalinity is the same.
Aquarists may rightly wonder whether organisms are able to photosynthesize efficiently as the pH is raised. The answer is mixed. Some can and some cannot. Those organisms that rely solely on carbon dioxide may not. Those that rely on both carbon dioxide and bicarbonate have a better chance of retaining efficiency at higher pH because a much larger amount of bicarbonate is present, and it does not change as rapidly with pH over the range of interest to aquarists.
Table 1 shows the response of a variety of macroalgae in terms of their ability to photosynthesize at pH 8.1 and 8.7. In seawater with constant carbonate alkalinity, there is 20% as much carbon dioxide at pH 8.7 as at pH 8.1, so an organism relying on carbon dioxide alone might experience a large drop in photosynthetic rate over this range. Clearly, the response varies with species. Chaetomorpha aerea, in particular, may be of substantial interest to aquarists. It is not necessarily the exact species that many grow in refugia (which is unidentified as far as I can tell), but this species of Chaetomorpha shows a 25% drop in photosynthesis when exposed to the higher pH. That drop is not as large as some other species, but may still be important, and it is more than many other species of macroalgae.
Of course, the photosynthesis rate does not necessarily translate to growth rates. If other nutrients are limiting growth (nitrogen, phosphorus, iron, etc.), then it may not matter if the rate of photosynthesis is reduced at higher pH. But because these nutrients are often present in surplus in reef aquaria, it may well be that carbon uptake is limiting in some cases, and in those cases aquarists might benefit from ensuring that the pH is not too high.
Species of macroalgae:
Relative photosynthesis at pH 8.7 compared to pH 8.1 (as a %):
Chaetomorpha aerea
Cladophora rupestris
Enteromorpha compressa
Ulva rigida
Codium fragile
Asparagopsis armata
Gelidium pusillum
Gelidium sesquipedale
Gymnogongrus sp.
Osmunda pinnatifida
Porphyra leucosticta
Fucus spiralis
Colpomenia sinuosa
Dictyota dichotoma
Cystoseira tamariscifolia
Padina pavonia
Table 1. Relative rates of photosynthesis19 in seawater (measured by oxygen evolution) at pH 8.7 relative to pH 8.0. A value of 100 means that the rates were the same, and values below 100 indicate less photosynthesis at pH 8.7.
Photosynthesis of Algae Relative to Their Natural Environment

Enough marine algae have been studied with respect to carbon uptake to allow certain comments about their capabilities to collect carbon in relation to their natural habitat. In a study of 38 species of red algae, researchers20 found that subtidal algae were more often restricted to using carbon dioxide, while intertidal species could typically use both carbon dioxide and bicarbonate. In fact, their ability to use bicarbonate correlated strongly to their positioning along a rocky coastline, with the efficiency increasing with tidal height, except for those species at the very top of the tideline, which showed a reversal of that trend. Similar results have been found for other studies of macroalgae, including green and brown algal species.21,22
Perhaps such relationships relate to the likelihood of spending considerable time in small closed tidal pools, where carbon dioxide would be more limited than in the open water, while at the very top of the shore, where exposure to air is most likely, the algae are again able to gain adequate carbon dioxide. The actual mechanisms used by some species (the brown alga Hizikia fusiforme,23 for example) that have multiple mechanisms actually change when exposed to air (taking up CO2 directly) and when immersed in seawater (using bicarbonate).
Photosynthesis of Algae in Continuous Light vs. Light/Dark Cycles

Interestingly, three marine microalgae, Skeletonema costatumPhaeocystis globosa and Emiliania huxleyi,24 were studied for their rates of photosynthesis and carbon uptake mechanisms in continuous light vs. those same species in light/dark cycles (12 h on/12 h off and 16 h on/8 h off). The rates of photosynthesis were nearly twice as high with light/dark cycles as with continuous lighting. In two of the species (S. costatum and E. huxleyi), but not the third, the contribution of bicarbonate to the total carbon uptake increased dramatically in light/dark cycles compared to continuous light.
How this result might relate to growth and nutrient uptake in lit refugia where macroalgae are often grown to export nutrients is not known. However, it is a sign that perhaps continuous light is not optimal, in addition to being more expensive.
Implications for Reef Aquarium Husbandry

Aquarists can do several things to ensure the ready availability of carbon dioxide to photosynthetic marine organisms. While adequate studies have not been done with the exact species and exact conditions present in a reef aquarium to make definitive statements, it may be prudent to follow the following principles in order to maximize photosynthesis:
1. Limit the maximum pH attained in reef aquaria. I'd suggest limiting the pH to no more than 8.5, and lower is better from a photosynthesis perspective (although pH below 8.2 has its own disadvantages related to rates of calcification by corals and coralline algae).
2. Put a lit refugium containing macroalgae on a reverse light cycle to the main tank. Not only will this limit the maximum pH attained in both the refugium and the main aquarium, but it keeps the pH lower in the refugium precisely when the organisms in it most need the pH to be lower (during the refugium light cycle when CO2 is required).
3. Do not drip limewater (kalkwasser) into or upstream of a lit macroalgae refugium, because it limits availability of CO2.
4. Add the effluent of a CaCO3/CO2 reactor into or upstream of a lit macroalgae refugium, as it increases the availability of CO2.
5. The data on continuous light vs. day/night cycling are intriguing and suggest that a dark cycle may benefit lit macroalgae refugia, especially when the cost of the electricity to drive the lights is considered.
6. Keep the carbonate alkalinity up to at least 2.5 meq/l (7 dKH; 125 ppm calcium carbonate equivalents) to provide adequate bicarbonate for photosynthesis. Higher alkalinity may even be better, especially if the pH is also high, limiting carbon dioxide itself as a CO2 source for photosynthesizing organisms. This suggestion is likely already followed by most reef aquarists, but perhaps not by some with fish-only or related types of aquaria that also rely on macroalgae for nutrient export.

The availability of carbon dioxide can be an important factor determining the rates of photosynthesis in marine organisms. Even though bicarbonate is used by many marine organisms, the ability of some species to photosynthesize may be limited by the pH and the availability of carbon dioxide. To be honest, before putting together this article, I had not worried much about such issues. My system deviates from several of the suggestions in the previous section (the pH often hits 8.5 or a tad higher, the lighting is continuous in three of my four refugia, etc.). I wonder what else I might learn about how to care for my system as I explore additional chemical aspects of photosynthesis in future articles?
Happy Reefing!

If you have any questions about this article, please visit my author forum on Reef Central.

1. Dinoflagellate symbioses: strategies and adaptations for the acquisition and fixation of inorganic carbon. Leggat, William; Marendy, Elessa M.; Baillie, Brett; Whitney, Spencer M.; Ludwig, Martha; Badger, Murray R.; Yellowlees, David. Biochemistry and Molecular Biology, James Cook University, Townsville, Australia. Functional Plant Biology (2002), 29(2/3), 309-322. Publisher: CSIRO Publishing.
2. Carbon acquisition mechanisms of algae: carbon dioxide diffusion and carbon dioxide concentrating mechanisms. Raven, John A.; Beardall, John. Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee, Dundee, UK. Advances in Photosynthesis and Respiration (2003), 14(Photosynthesis in Algae), 225-244. Publisher: Kluwer Academic Publishers.
3. Algae lacking carbon-concentrating mechanisms. Raven, John A.; Ball, Lucy A.; Beardall, John; Giordano, Mario; Maberly, Stephen C. Scottish Crop Research Institute, University of Dundee at SCRI, Invergowie, Dundee, UK. Canadian Journal of Botany (2005), 83(7), 879-890. Publisher: National Research Council of Canada.
4. Inorganic carbon acquisition by the chrysophyte alga Mallomonas papillosa. Bhatti, Shabana; Colman, Brian. Department of Biology, York University, Toronto, ON, Can. Canadian Journal of Botany (2005), 83(7), 891-897. Publisher: National Research Council of Canada.
5. How do marine diatoms fix 10 billion tonnes of inorganic carbon per year? Granum, Espen; Raven, John A.; Leegood, Richard C. Robert Hill Institute and Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK. Canadian Journal of Botany (2005), 83(7), 898-908. Publisher: National Research Council of Canada.
6. The diversity of inorganic carbon acquisition mechanisms in eukaryotic microalgae. Colman, Brian; Huertas, I. Emma; Bhatti, Shabana; Dason, Jeffrey S. Department of Biology, York University, Toronto, ON, Can. Functional Plant Biology (2002), 29(2/3), 261-270. Publisher: CSIRO Publishing.
7. Source of inorganic carbon for photosynthesis in two marine dinoflagellates. Dason, Jeffrey S.; Huertas, I. Emma; Colman, Brian. Department of Biology, York University, Toronto, ON, Can. Journal of Phycology (2004), 40(2), 285-292. Publisher: Blackwell Publishing, Inc.
8. Acquisition of inorganic carbon by the marine haptophyte Isochrysis galbana(Prymnesiophyceae). Bhatti, Shabana; Huertas, I. Emma; Colman, Brian. Department of Biology, York University, Toronto, Can. Journal of Phycology (2002), 38(5), 914-921. Publisher: Blackwell Publishing, Inc.
9. Photosynthetic utilisation of inorganic carbon and its regulation in the marine diatom Skeletonema costatum. Chen, Xiongwen; Gao, Kunshan. Department of Biology, Hubei Normal University, Huangshi, Peop. Rep. China. Functional Plant Biology (2004), 31(10), 1027-1033. Publisher: CSIRO Publishing.
10. Photosynthetic responses to inorganic carbon in Ulva lactuca under aquatic and aerial states. Zou, Dinghui; Gao, Kunshan. Marine Biology Institute, Science Center, Shantou University, Shantou, Peop. Rep. China. Acta Botanica Sinica (2002), 44(11), 1291-1296. Publisher: Science Press.
11. Photosynthetic use of exogenous inorganic carbon in the agarophyte Gracilaria lemaneiformis (Rhodophyta). Zou, Dinghui; Xia, Jianrong; Yang, Yufeng. Marine Biology Institute, Science Center, Shantou University, Shantou, Peop. Rep. China. Aquaculture (2004), 237(1-4), 421-431. Publisher: Elsevier.
12. Photosynthetic utilization of inorganic carbon in the economic brown alga, Hizikia fusiforme (Sargassaceae) from the South China Sea. Zou, Dinghui; Gao, Kunshan; Xia, Jianrong. Marine Biology Institute, Science Center, Shantou University, Guangdong, Peop. Rep. China. Journal of Phycology (2003), 39(6), 1095-1100. Publisher: Blackwell Publishing.
13. Inorganic carbon acquisition in two species of marine prymnesiophytes. Huertas, I. Emma; Bhatti, Shabana; Colman, Brian. Instituto de Ciencias Marinas de Andalucia (CSIC), Puerto Real, Spain. European Journal of Phycology (2003), 38(2), 181-189. Publisher: Taylor & Francis Ltd.
14. Photosynthetic carbon acquisition in the red alga Gracilaria conferta. II. Rubisco carboxylase kinetics, carbonic anhydrase and bicarbonate uptake. Israel, A.; Beer, S. Dep. Bot., Tel Aviv Univ., Tel Aviv-Jaffa, Israel. Marine Biology (Berlin, Germany) (1992), 112(4), 697-700.
15. Inorganic carbon acquisition in red tide dinoflagellates. Rost, Bjoern; Richter, Klaus-Uwe; Riebesell, Ulf; Hansen, Per Juel. Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany. Plant, Cell and Environment (2006), 29(5), 810-822.
16. Evidence for K+-dependent HCO3- utilization in the marine diatom Phaeodactylum tricornutum. Chen, Xiongwen; Qiu, C. E.; Shao, J. Z. Department of Biology and Hubei Key Laboratory of Bioanalytical Technique, Hubei Normal University, Hubei, Peop. Rep. China. Plant Physiology (2006), 141(2), 731-736.
17. Carbon acquisition mechanisms of algae: carbon dioxide diffusion and carbon dioxide concentrating mechanisms. Raven, John A.; Beardall, John. Division of Environmental and Applied Biology, School of Life Sciences, University of Dundee, Dundee, UK. Advances in Photosynthesis and Respiration (2003), 14(Photosynthesis in Algae), 225-244. Publisher: Kluwer Academic Publishers.
18. Use of light and inorganic carbon acquisition by two morphotypes of Zostera noltiiHornem. Mercado, Jesus M.; Niell, F. X.; Silva, Joao; Santos, Rui. Centro Oceanográfico de Malaga, Instituto Espanol de Oceanografia, Malaga, Spain. Journal of Experimental Marine Biology and Ecology (2003), 297(1), 71-84. Publisher: Elsevier Science B.V.
19. External carbonic anhydrase and affinity for inorganic carbon in intertidal macroalgae. Mercado, Jesus M.; Gordillo, F. Javier L.; Figueroa, Felix L.; Niell, F. Xavier. Dep. Ecol., Univ. Malaga, Malaga, Spain. Journal of Experimental Marine Biology and Ecology (1998), 221(2), 209-220. Publisher: Elsevier Science B.V.
20. Habitat matters for inorganic carbon acquisition in 38 species of red macroalgae (Rhodophyta) from Puget Sound, Washington, USA. Murru, Maurizio; Sandren, Craig D. Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI, USA. Journal of Phycology (2004), 40(5), 837-845. Publisher: Blackwell Publishing, Inc.
21. External carbonic anhydrase and affinity for inorganic carbon in intertidal macroalgae. Mercado, Jesus M.; Gordillo, F. Javier L.; Figueroa, Felix L.; Niell, F. Xavier. Dep. Ecol., Univ. Malaga, Malaga, Spain. Journal of Experimental Marine Biology and Ecology (1998), 221(2), 209-220. Publisher: Elsevier Science B.V.
22. CO2 concentrating mechanisms in algae: Mechanisms, environmental modulation, and evolution. Giordano, Mario; Beardall, John; Raven, John A. Department of Marine Science, Universita Politecnica delle Marche, Ancona, Italy. Annual Review of Plant Biology (2005), 56 99-131. Publisher: Annual Reviews Inc.
23. Comparative mechanisms of photosynthetic carbon acquisition in Hizikia fusiformeunder submersed and emersed conditions. Zou, Dinghui; Gao, Kunshan. Science Center, Marine Biology Institute, Shantou University, Shantou, Peop. Rep. China. Acta Botanica Sinica (2004), 46(10), 1178-1185. Publisher: Science Press.
24. Carbon acquisition of marine phytoplankton: effect of photoperiod length. Rost, Bjoern; Riebesell, Ulf; Sueltemeyer, Dieter. Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany. Limnology and Oceanography (2006), 51(1), 12-20. Publisher: American Society of Limnology and Oceanography.

Thursday, 17 July 2014

Wastewater Treatment Ponds

Lesson 5:
Wastewater Treatment Ponds

In this lesson we will answer the following questions:
  • What are wastewater treatment ponds?
  • What are the types of bacteria at work in most ponds?
  • How is oxygen provided to the wastewater?
  • What is the algae cycle and why is it important?
  • What role does temperature play in wastewater treatment ponds?

Reading Assignment
Read the online lesson and also Chapter 9 in textbook, Operation of Wastewater Treatment Plants Vol. 1.

Wastewater treatment using ponds can be an economical way of treatment which produces effluent that is highly purified. The number and the type of ponds used are the determining factors as to the degree of treatment that is provided.
Another name for wastewater treatment ponds is waste stabilization ponds . For this lesson we use waste stabilization ponds because these ponds help to stabilize the wastewater before it is passed on to receiving water. They can also be referred to as oxidation ponds or sewage lagoons .
The waste stabilization pond is a biological treatment process , where bacteria use organic matter in the wastewater as food. The three types of bacteria at work in most ponds are the aerobic, anaerobic, and the facultative bacteria.
Because of unpleasant conditions associated with the anaerobic decomposition, plant operators must make sure that there is enough dissolved oxygen (D.O.) in the pond to make sure that it will be the aerobic and facultative bacteria that will be predominant, rather than having anaerobic decomposition take place.

How oxygen is supplied in the ponds
One way that oxygen is supplied to the wastewater is by algae . The algae produce the oxygen needed by the bacteria and the bacteria in turn produce carbon dioxide and other things that are needed by the algae.
It is important to remember that the algae will thrive when there is sunlight present. They cannot grow at nighttime, or during extended periods of cloudy weather. The water in the ponds has to be clear and not too deep. If the sunlight can reach the bottom, then the algae will grow throughout the pond depth. The following drawing shows the Algae Cycle)

If the water is not clear or if the sunlight is cutoff the algae will not grow. If this happens, the D.O. level in the pond will decrease and you can expect an increase in anaerobic activity at the bottom of the pond. The thickness of the anaerobic layer at the bottom will probably increase.
In ponds that are over three feet deep , you can expect that there will be a zone where the concentration of dissolved oxygen will vary from time to time. You can also expect facultative bacteria living in this zone because only they can adjust to the aerobic and anaerobic conditions existing.

How weather and seasons of the year affect the ponds
Another thing to be aware of are the things that you can expect to happen in the pond during the winter. In winter, shorter periods of daylight, cloudy weather, and snow or ice can prevent the sunlight from reaching the wastewater. Small amounts of oxygen will be produced by the algae and there will be no aeration from wind action because of the ice cover. Colder temperatures will slow down the activity of the bacteria . By this, the pond is continuously discharging and the effluent will be worse. But in the spring when the pond warms up, there will be an increase in bacterial action on the material that was deposited during the winter. The result will be odors from anaerobic conditions. Another reason for the pond odors in the spring is spring turnover. As the pond warms, the bottom layer of the wastewater starts to mix throughout the pond. When this happens, it brings with it smelly gases and some solids. Spring turnover odors usually last about 7 days.
Although there is a greater die-off of bacteria in ponds than in other treatment methods because of the longer detention time in ponds, pond effluent may still require disinfection to preserve receiving stream quality. It is the bacteria that do the treatment in the ponds. The kind of bacterial action that will take place is determined by the amount of dissolved oxygen available in the pond.

Types of Wastewater Treatment Ponds
In this section we will look at 7 different types of wastewater treatment ponds (waste stabilization ponds) and what process occurs in each.

Aerobic Pond
In the aerobic pond oxygen is present throughout the pond and all biological activity is aerobic decomposition. Aerobic ponds are a maximum of two feet deep, so that the sunlight can reach throughout the entire depth of the pond, which will let the algae grow throughout. The oxygen they give off allows aerobic process microorganisms to live. Aerobic ponds are not used in colder climates because they will completely freeze in the winter.

Anaerobic Pond
Anaerobic ponds are normally used to treat high strength concentrated industrial waste and no oxygen is present in the pond. All the biological activity is anaerobic decomposition. These ponds are 8 to 12 feet deep and are anaerobic throughout. Scum forms on the top of the most anaerobic ponds. This scum stops air from mixing with the wastewater. Because there is no dissolved oxygen in the pond the anaerobic bacteria will be a work. The gases that is produced by the anaerobic bacterial action causes odor problems and these types of ponds are not used very often.

Facultative Pond
Facultative ponds are used the most to treat municipal wastewater. The ponds are usually 4 to 6 feet deep and the sludge at the bottom is anaerobic, while the 1 to 2 feet of the top of the pond is aerobic. In the middle, the amount of dissolved oxygen varies and either aerobic or anaerobic decomposition will take place, depending on how much dissolved oxygen is available.
Facultative Stabilization Pond

Oxidation Pond
This type of pond is designed to receive flows that have passed through a stabilization pond or primary settling tanks. These ponds provide biological treatment and additional settling and some reduction in the number of fecal coliform present. They are normally designed by the same specifications as the stabilization pond.

Raw Sewage Stabilization Pond
This type of pond is the designed to receive wastewater that has had no prior treatment except for screening and shredding and is the most common of them all. These ponds are designed to provide a minimum of 45 days detention time and to receive no more than 50 pounds of BOD 5 per day per acre. The normal operating depth is 3-5 feet. In this time of pond the time of the year determines the quality of the discharge. The summer months produce high BOD 5 removals but low suspended solids removal and in the winter months there is poor BOD 5 removal but excellent suspended solids removals. The process that occur in this type of pond are, settling, aerobic, facultative, anaerobic decomposition and photosynthesis to produce required oxygen.

Polishing Pond
This type of pond is designed to receive flow from the oxidation pond and from other secondary treatment systems. This process removes additional BOD 5, solids and fecal coliform and other nutrient removal. These types of ponds provide only a 1 to 3 day detention time and normally operate at a depth of 5-10 feet. If the detention time excessive, then there will be an increase in the effluent suspended solids concentration.

Aerated Pond
In these ponds, oxygen is provided by using mechanical or a diffused air system (artificial aeration). The artificial aeration also keeps the wastewater in the pond mixed, keeping organics and bacteria in contact. The aeration allows the pond to have shorter detention times and heavier loading.

Wastewater treatment ponds are designed for different types waste and may or may not contain oxygen. Not all ponds are suited for all regions or climates. Dissolved oxygen levels must be maintained. Algae must be present to provide oxygen. Not all ponds have the same detention time and must be maintained for odor control.

Answer the following questions and email your answers to
  1. Why do we consider wastewater treatment ponds an economical treatment method?
  2. What is the most common type of pond used?
  3. What is provided in the oxidation pond how is it designed?
  4. What is removed in a polishing pond?
  5. How is oxygen supplied in an aerated pond?
  6. Oxygen is present in what type/types of ponds and which ponds have no oxygen?
  7. What type of pond has no oxygen in the lower level?
  8. How many pounds per day per acre can a raw sewage stabilization pond receive?
  9. What months have poor BOD5?
  10. What type of pond receives industrial wastes?

Answer the questiosn for the Lesson 5 Quiz. When you have completed the quiz, print it and fax or email it to your instructor. You may also take the quiz online and directly submit it into the database for a grade.

Sunday, 13 July 2014

Is Your Body Demanding Food Enzymes?

By Dr. Edward Howell
The following article was written by Dr. Howell late in his life, in an attempt to make clear his revolutionary food enzyme concept.
In spite of all I have written about food enzymes since 1936, common misconception persists and distort their significance in nutrition. Let me restate that all animal and vegetable foods in their natural state contain non-caloric elements in addition to proteins, carbohydrates, and fats. In the order of their discovery and recognition as indispensable food elements, they are minerals, vitamins, and enzymes. It is obvious that merely discovering that foods are endowed by nature with any particular non-caloric food material should constitute all the proof needed to establish this substance as a protector of the health and well-being of living organisms, including the human race, during the whole life span. This is because constituents of unprocessed natural foods have had countless eons of time to mold and shape the form and function of living organisms, and have created a dependence to fill a need. Therefore, to remove any part of natural food from the normal diet could not be sanctioned because of the possibility of harm to the health and well-being.
This has been shown by the history of nutrition. Not very long ago, the only elements considered necessary for wholesome nutrition were protein, carbohydrates, and fats. Minerals were considered unimportant and ignobly characterized by chemists as "ash" because they were all that remained after food was burned in the laboratory. Vitamins and enzymes in foods were unknown. The fiber of foods was removed and discarded because fiber was believed to be too coarse for the human digestive tract. Many people formerly believed that vegetables were fit food only for rabbits and cows - not humans. The immigrants flooding here from Europe during the early years of this century, foolishly embraced white bread with open arms. In the backward, unindustrialized countries, only the wealthy ate white bread, the common people having to be satisfied with whole-grain bread, of whose health value they were ignorant. The bran of wheat, which we now value as necessary food fiber, along with the valuable wheat embryo or germ, were removed and found their way into rations for cattle and hogs, proving to serve as excellent nutrition for these animals.
For over a hundred years, enzymes had a reputation as being important in the digestion of food, and that was all. Their area of operation was believed to be limited to the stomach and intestines. It was not realized until recently that the work of enzymes in the digestive tract is only a minor part of their complete duties in the bodies of animals and human beings. Enzymes are the active agents in metabolism - in anabolism and catabolism. Enzymes are the actors behind the scenes in the immunity processes. They power your thinking, breathing, sexual activity - your very life. Thousands of different enzymes - metabolic enzymes - are involved in everything going on in the heart, lungs, liver, arteries, blood, muscles - in all organs and tissues. Your body is expected to make all of these digestive and metabolic enzymes.
But while the body is required to produce less than a dozen essential digestive enzymes, functioning only in the food canal, it must furnish thousands of metabolic enzymes to service the multitudinous activities of the entire organism. Metabolic enzymes do work, they are workers. They take absorbed food products with their minerals and vitamins, and build them into tissues. They repair the body and aim to keep the organs healthy. Furthermore, through substrate action, metabolic enzymes remove worn-out material from the cells, keeping everything in repair. It can be recognized that this is a far bigger job for enzymes than merely digesting food in the food canal, part of which should be done by food enzymes, or if need be, by other exogenous enzymes, meaning supplemental enzymes. So which are more important in the body, digestive enzymes, or metabolic enzymes? Let us beware about permitting a metabolic enzyme labor shortage to form, which can induce our problem diseases.
If metabolic enzymes are more important, then why must they play second fiddle, and have second call in the allocation of the body's resources? Why are digestive enzymes kept rich by having first call on the limited enzymes potential of the organism, while the more important metabolic enzymes must be satisfied with what is left? I must emphasize that the reader of this treatise is an owner of the serviceable and precious metabolic enzymes. Smart owners will not force their digestive enzymes to do work meant for food enzymes if this extra burden on the digestive enzymes requires the body to put a strain on producing their multi-functional metabolic enzymes and not have enough of them to carry on their important functions. If you were a biological engineer, responsible for efficient operation and health of human organisms, is it not logical that you would see to it that the digestive enzymes be given less work by allowing food enzymes, or supplemental enzymes, if need be, to do more digesting, as evolution, or the God of nature's laws, ordained?
Each plan, animal, and human being can make the enzymes needed to do that which needs to be done in the organism. Any high school student knows that the human digestive glands can make the enzymes needed to digest our foods. Some well-informed students also know that human saliva and pancreatic juice are fabulously rich in enzymes, far stronger than in any wild animal living under the laws of nature. The uninitiated and perplexed reader may reasonably ask why we need the enzymes in food when our digestive enzymes, in prime of life, can do the job well. "Are not food enzymes superfluous and nonessential," some people may ask. Even those in high places have been beset by difficulties in discerning the hidden facts. To clarify an otherwise muddled situation, is precisely why I wrote this narrative. But before proceeding, it is urgent to call attention to yet another important pillar in the Food Enzyme Concept.
Let me repeat again the bast difference between vitamins and enzymes in food, and the unique quality that separates enzymes from all other food factors and establishes food enzymes as very special food ingredients. I refer to their extreme vulnerability to destruction by heat. Whereas, most food factors, including vitamins, suffer only minor or no demonstrable harm from heat preparation in the kitchen or factory, enzymes are completely destroyed by manufacturing or culinary operations. Enzymes can withstand no cooking, boiling, frying, roasting, stewing, broiling, or pasteurizing. Cookery destroys them to the extent of - not 99%, but 100%.
Now, permit me to return to the matter of why food enzymes are so important and indispensable to the reader's present and future health - possibly even more so where digestive juices are overflowing with personal enzymes. In the first place, all of nature's creatures welcome and receive food enzymes, in every morsel of food, in addition to the enzymes they produce. Fish are surrounded by enzymes as they swim in the ocean water. Plants are dependent on free enzymes in the soil to help make plant food, and suffer increased susceptibility to disease when they must subsidize deficient soil enzymes with their own metabolic enzymes. When you eat raw food, the enzymes within it are immediately released and begin to digest it in the mouth, even before being swallowed, and before your own enzymes are even secreted.
The same happens with animals living on raw food. When birds, like the chicken, swallow intact wheat or corn seeds, they go into the crop. There the seeds swell with moisture and the food enzymes inside the seeds begin to digest the starch, protein, and fat before the seeds reach the stomach of the bird. Snakes and many other creatures eat their food by swallowing it entirely without chewing. Small snakes swallow live rats, frogs, and such. Large snakes, such as the python, engulf live pigs. The body of the hapless victim shows up as large bolus in the midriff, causing an enormous distention of the stomach of the snake, which allows no room for the snakes enzymes or acid to enter. Only after the digestive enzymes and catheptic enzymes of the prey, which now belong to the snake, and have become its food enzymes, have performed the ritual of predigestion, and liquefier the body of the prey, can the snake's enzymes find room in tis own stomach, to proceed with digestion.
Millions of fish swallow entire smaller fish every day as their normal diet, while millions of birds gulp down entire fish or other organisms to constitute their complete food intake. And thus, the ritual of predigestion by food enzymes is carried on in the entire animal kingdom. A lion has teeth adapted only to tear away large chunks of meat from the body of prey. He may tear off thirty pounds of chunks and then walk away dragging a full belly to a sanctuary to rest, while the pressure from the enormous distention of his stomach by the meat forms a coalescent bolus which crowds out everything, giving no room for the lion's acid and enzymes to enter. The lion's peptic enzymes and acid can find room to get into its stomach only after the catheptic enzymes within the meat itself have performed their role of predigestion and reduced the bolus to a plastic or liquid consistency. Only then can the lion's enzymes carry on the digestive process from where the cathepsin stopped. It is indeed a law of nature, tested and proven by millions of years that enzymes within the food have been ordained by evolution, or evolution's God, to predigest food, and that your private enzymes were never intended to do the job alone.
Must we pay a penalty when we alone, of the hundreds of thousands of species of living treasures on this earth, force our unaided, personal (endogenous) digestive enzymes to digest food, instead of letting exogenous (outside) enzymes do part of the job by predigestion, according to nature's law? There is a penalty which is inescapable and cumulative. It is deceptively unnoticeable when we are young, but when our bodies are permanently called upon to make too many enzymes for digestion, the stress of competition for enzymes, forces our organism to produce less of the other kinds of enzymes needed to keep all organs and tissues in proper repair and health.
In other words, if the body has very rich digestive enzymes, it must be satisfied with poor metabolic enzymes. The organism cannot at the same time make very rich digestive enzymes, and very rich metabolic enzymes, but a hypersecretion of one kind can be attained only at the expense of a hyposecretion of the other kind. The old saying that the man with an "iron stomach" is the prime candidate for an early heart attack, is unfortunately quite true. When we flirt with the integrity of metabolic enzymes, and abuse the enzymes' potential, we are inviting the most serious types of intractable diseases to come in and establish house-keeping. We are notifying cancer, cardiovascular disease, diabetes, etc., to make themselves at home in our bodies. Food-enzyme deficiency and its aftermath must be recognized as the most serious and profound oversight and omission in nutrition.
Since wild animals do not cook, what is there to prevent ingested food enzymes from predigesting the food of wild animals? This leaves the human race in the unenviable and isolated position of being the only living creatures forcing their digestive enzymes to suffer the burden of unaided digestion of food, which in turn, is reflected in compromising the potency of metabolic enzymes. Anything lowering the efficiency of metabolic enzymes, impairs their ability to keep the organ systems healthy enough to ward off disease. The fact that the health of people and their domesticated animals does not measure up to the high standards of wild animals, offers support to indications that the relative potency of metabolic enzymes plays a key role in the health discrepancy. Professional experience has shown that those domesticated and laboratory animals eating a human-type diet, are plagued with a variety of human-type serious diseases after they pass the middle of the life span. On the contrary, wild animals are immune to our problem diseases, unless they are exposed to toxic influences, or fed at our garbage dumps. The animals of the deep jungle are singularly free of degenerative and problem diseases which affect people and their pets and farm animals.
It is sometimes said that food enzymes or supplemental enzymes swallowed with food cannot do any work because the acid in the stomach prevents their activity. This is true if the enzymes and very strong acid are mixed together in a test tube in a laboratory demonstration. But it is untrue when enzymes are taken into a living body. The stomach normally allows salivary enzymes, food and supplementary enzymes to digest food for up to an hour. When they have finished their job of performing predigestion, food enzymes and proper supplemental enzymes, functioning at a lower PH, continue digestion of protein, carbohydrate, and fat for a longer time than salivary or pancreatic enzymes; salivary digestion being restricted to starch. As the stomach acid level becomes higher, the special acid enzyme, pepsin, can continue the digestion of protein where the others left off. These facts have been elicited after the stomach and upper intestinal contents were pumped out and examined at various intervals following meals.
I have been able to show the dire consequences following use of the enzyme-deficient diet by discovering that the pancreas must enlarge to produce the vast quantities of enzymes necessary when the body is forced to digest all of the food without outside aid. This down not harm the pancreas at all, any more than it harms a muscle when it must enlarge to do more work. Similarly, when a government agency must enlarge to give away more money to foreign governments, the only harmed parties are the taxpayers. An enlarged pancreas can give out and waste more precious enzymes than a normal organ, but this generous dispensation is not good for the body as a whole because it strains the enzyme potential of the whole body in tis effort to produce a normal quota of metabolic enzymes to keep all organs and tissues healthy and disease-free.
Those who theorize that food enzymes do not digest food in the human stomach, thereby confess ignorance of the fact that physiologists fed test meals and waited for the salivary enzyme, ptyalin, to work on them. Later, the contents of the duodenum and stomach were pumped out and it was learned that marked digestion of the food consumed occurred in both instances. And a large portion of the enzymes fed with the food, were recovered, proving that they were not permanently inactivated, and furthermore, that theoretical prognostication can be dangerous.
There are those who surreptitiously proclaim that food enzymes cannot do any work in the stomach because all enzymes are proteins, and food enzymes are digested as are other proteins. But this argument very conveniently overlooks, or perhaps tries to hide the fact, that if the enzyme complex had no special and specific immunity against being digested because it contains protein, what is to prevent one portion of the enzyme pepsin from being digested by an adjoining and contiguous portion of the same enzyme while pepsin functions in the stomach? Why do pancreatic proteolytic enzymes not digest each other while they are at work reducing food proteins to amino acids in the small intestine?
Further evidence that food enzymes have been ordained by nature over countless millions of years to help digest the food of all creatures, including human beings, is supplied by special organs with no function except to serve as food-enzymes stomachs. Food enzymes are made up of proteolytic food enzymes to digest protein, amyloytic food enzymes to digest carbohydrates, and lipolytic food enzymes to digest fats. The so-called killer whale, a member of Cetacea, has a food enzyme stomach larger than any land creature. The food-enzyme stomach of this whale has been found to contain more than a dozen porpoises and seals. In one instance this enormous food enzyme stomach, which is the first of the whale's three stomachs, and much larger than the others, was found to house the bodies of 32 entire seals undergoing digestion by the seal enzymes, which now belong to the whale, and are the whale's food enzymes. The remarkable fact elicited by physiologists is that the first stomach (forestomach) has no enzymes or acid of its own at all. Its membranes have no glands to produce these agents for digestion. The first stomach is simply a large reservoir which provides space for the enzymes within the bodies of swallowed animals to digest their own bodies to a sufficiently plastic or liquid consistency which enables the food material to pass through a small opening connecting the first stomach to the second stomach, which makes enzymes to continue the digestion.
For hundreds of years human beings felt quite sure they had only a single stomach to digest food. But scientists have found this is not strictly true, and that humans have a digestive organ functioning as two stomachs. The upper part, or cardiac end, produces no acid or enzymes and is a food-enzyme stomach. It has been designed as a reservoir to receive food, and permit the enzymes in the food itself to predigest the food for further digestion by the chain of enzymes along the digestive tract. Therefore, the human being also owns a food-enzyme stomach. This fact, along with the other evidence I have presented, establishes food enzymes as cardinal digestive agents, making it impossible for anyone to lightly brush them aside.
The foregoing avalanche of relevant information supports the recently discovered law of the adaptive secretion of digestive enzymes which proclaims that the body values enzymes highly and produces no more of them than it is forced to. If more digestive food enzymes are eaten, the body will automatically make fewer digestive enzymes and can then produce more metabolic enzymes, should they be needed. The body will therefore be in a better position to prevent or deal with the problems of killer diseases.

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