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Subscribe to the AIA newsfeed and get the latest tips and tricks in the wastewater industry. Written by Richard Runion.


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january 22, 2008 06:27pm

microbiological wastewater treatment

The biological process of wastewater is a secondary treatment involving the components of removing, stabilizing and rendering harmless very fine suspended matter, colloids and dissolved solids of the sewage, that come from the sedimentation tank, where most of the matter in suspension has been removed. In some cases, effluent from sedimentation tank may be good enough for disposal if the dilution is great. However, in most cases, oxidation of the organic putrescible matter is necessary.
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**Principle of action**

The primary principle of action on which the biological process is based is the availability of a large sewage surface fed by the oxygen from air, where certain type of bacteria, the aerobics, live and use that oxygen to oxidize putrescible matter in the sewage to stable and inoffensive sulfates, nitrates and other compounds.

The sewage filtration, which is the vehicle used for process, can at best cause only the coarser particles of suspended matter to be removed by mechanical straining. This action is only minor and of a secondary nature. The major action takes place at the surface, where the aerobic bacteria oxidizes the finer organic particles of sewage abounding large surface areas, forming a bacterial film. is formed. The film adsorbs more of the finer matter which is then worked upon by the organisms present after which it is released as a coagulated suspended matter, rather heavy and capable of settling readily.

It should be noted that this bacterial film also contains, in addition to the aerobic bacteria, other organisms as protozoa, algae, besides certain species of worms. But their action is somewhat uncertain and the biological action is considered to be mainly due to the aerobic bacteria.

**Microbiology of wastewater treatment**

Most wastewaters have putrifying (rotting in due course) organic matter. Biological wastewater treatment systems are to covert the organic matter into easily manageable end products, such as carbon dioxide, methane and humus, which can be utilized or disposed off without affecting the environment. The microorganisms use the organic matter as food to provide energy and carbon for cellular synthesis.

Industrial fermentation uses aseptic techniques to maintain pure cultures and the environment is controlled. Biological wastewater treatment systems are only partially controlled. The wastewater (substrate or food) characteristics may change from time to time, there are changes in temperature and there is always a heterogeneous inoculum of microorganisms from soil and air. This results in a variety of microorganisms participating in the reaction. The fittest survive and dominate the population. When the compounds in wastewater are metabolized, intermediate compounds serve as food for other microorganisms.

The population of individual microorganisms and the community structure also changes from time to time reflecting the changes in environmental conditions. It is possible to zero in on groups of microorganisms participating in the process, based on their overall biochemical reactions.

Today, we will continue from where we left on the microbiological wastewater treatment plant. I will compare the construction, uses, merits and demerits of different components of the microbiological wastewater treatment plant with reference to each other.

**Intermittent sand filters**

The treatment involved in the case of intermittent sand filters applies the sewage, that has already undergone preliminary treatment, onto the filter beds of sand at regular intervals. By this, air can enter the interstices of the bed between the dose of sewage to supply the required aerobic bacteria.

**Construction**

The filter consists of a layer of clean, sharp sand, with an effective size 0.2 - 0.5 mm and of uniformly coefficient 2 - 5, 75 to 105 cm deep having underdrains, surrounded by gravel to carry off the effluent. The sewage is applied by means of a dosing tank and siphon; it then flows into troughs laid on the filter bed. The troughs have side openings, which allow the sewage to flow on the sand. To prevent any displacement of sand, blocks may also be used underneath the sewage streams. After an interval of 24 hours, sewage is now applied over a second bed while the first bed rests.
Usually, three to four beds may thus be working in rotation. During the resting period, the dried sludge accumulating on the sand surface is the resting period; the dried sludge accumulating on the sand surface is scraped off. The organic loading of the filter bed is not heavy, only 0.825 to 1.1 million liters per hectare per day.

**Uses**

It is found that the effluent from an intermittent sand filter is usually better in quality than that resulting from any other type of treatment and can even be disposed off without dilution.
However, because of the large land area required, filters of this type are now seldom constructed in cities. They are primarily suited for institutions, hospitals and other small installations.

**Contact beds**

In this type, the sewage applied on the contact material is allowed to stand undisturbed for some time before, being emptied and an interval is allowed before recharging the bed. During the 'contact period', when the filter is standing full, the fine suspended particles of sewage are deposited on the contact material and worked over by the anaerobic organisms. During the 'empty period'
that follows next, the deposited matter is oxidized by the aerobic bacteria. It is then washed off the contact material and carried out with the effluent on the next emptying of the tank.

**Construction**

A contact bed is a watertight tank with masonry walls and very much similar in construction to an intermittent sand-filter. The contact material is made of broken stone called ballast and of 2.5 - 7.5 cm gauge. The tank is filled with the sewage over a period of an hour; allowed to stand full over a period of two hours, then emptied through underdrains. This process takes another hour. The tank is now left empty ffor 3 to 4 hours before admitting the next charge.
(Thus with a total working period in a shift of 8 hours, the contact bed can be worked in three shifts daily). The organic loading in this case is about the same i.e., 1.1 million liters per hectare per day.

**Uses**

The contact beds method is now only of historical interest and not commonly used. This is mainly because of the loss of efficiency brought about by the exclusion of air when the tank is standing full. For an efficient biological action, it is imperative That the aeration should be through the mass of sewage. It has therefore, been superseded by more efficient biological methods, as in the case of trickling filters and activated sludge plants.

However, the contact beds have some merit when compared to the trickling filters as:

A.Lesser operating head required
B.Freedom from filter (psychoda) flies
C.Lesser nuisance due to odor

**Activated sludge**

When wastewater is aerated sufficiently, its organic matter reduces and a flocculant sludge (consisting of various microorganisms) is formed. In order to improve the process, the flocculant activated sludge is retained in the system as inoculum. This is achieved by settling the wastewater and recirculating the microbial mass. A part of this sludge is wasted periodically as synthesis of new cells continues. The organisms involved are aerobic chemoheterotrophic, i.e., those which utilize organic compounds as source for carbon (for cellular synthesis) and energy (by using oxygen as electron acceptor).


1.Phase i: initially, the macromolecules are hydrolyzed or broken down into their monomer compounds. These reactions are usually carried out extracellularly. Once their size is reduced they are transported into the cell.
2.Phase ii: later, the small molecules produced in phase i are partially degraded, releasing 1/3rd of their total energy to the cell. In the process a number of different products are formed which serve as precursors of both anabolic and catabolic routes of phase iii.
3.Phase iii: the catabolic route oxidizes the compounds and produces carbon dioxide and energy. The anabolic route (which requires
energy) results in synthesis of new cellular material. Many microorganisms participate in the above reactions. Both the lower and higher protists have significant roles to play. Generally, the organisms in activated sludge culture may be divided into four major classes (these are not distinct groups and any particular organism may display more than one such behavior):

i. Floc-forming organisms: these help to separate the microbial sludge from the treated wastewater. Zooglea ramigera and a variety of other organisms flocculate. Flocculation is understood to be caused by the extracellular polyelectrolytes excreted by these microorganisms. Saprophytes: the saprophytes are micro-organisms that degrade the organic matter. These are mostly gram-negative bacilli such as pseudomonas, flavobacterium, alcaligenes and the floc formers.

ii. Predators: the main predators are protozoa which thrive on bacteria. It has been found that the protozoa can be upto 5% of the mass of biological solids in the systems. Ciliates are usually the dominant protozoa. They are either attached to or crawl over the surface of sludge flocs. Rotifers are the secondary predators. When rotifers occur in plenty, we can be sure of a well stabilized waste, since rotifiers perish in highly polluted waters.

iii. Nuisance organisms: nuisance organisms interfere with the smooth functioning of the system, when present in large quantities. Most problems arise due to sludge settling (due to presence of filamentous forms which reduce the specific gravity of the sludge).
The bacterium sphaerotilus natans and the fungus geotrichium are often responsible for this situation.

**Trickling filter**

Trickling filters have biomass growth attached to a solid surface over which the wastewater flows in thin sheets, supplying nutrients to the microbial community. The biochemical reactions are similar to those in an activated sludge, which have a rich mixture of:

Eucaryotic Procaryotic organisms

Trickling filters contain these and also higher life forms like:
Nematodes Rotifers Snails Sludge worms Insect larvae Filter flies
(psychoda)

The complex food chain prevailing in this allows complete oxidation of organic matter and lower quantity of surplus organisms (sludge).
The microbial film grows in thickness, due to increased hydraulic shearing and development of an anaerobic layer next to the solid medium. The anaerobic reactions solubilize the anchoring microorganism. Algae can also flourish on the upper surface.
However, they do not play significant role in waste stabilization.

Also called percolating filters, the trickling filters are similar to contact beds in construction, but allow constant aeration and the action is continuous. The name is a misnomer since the biological unit neither filters nor it trickles. The main function of a trickling filter is to remove unstable, organic materials in the form of dissolved and finely-divided organic solids and to oxidize these solids biologically to form more stable materials.
The biological process involved in the filter is due to the growth of a microbial film on the surface of the filter medium. The film is made up of zoogleal slime, viscous jelly-like substance containing bacteria and other biota. Under favorable environmental conditions, the slime adsorbs and utilizes suspended, colloidal and dissolved organic matter from the sewage. Although classified as an aerobic treatment device, the microbial film is aerobic to a small depth of 0.1 - 0.2 mm. While at the bottom, a larger depth is anaerobic. When the sewage is flowing over the film, the soluble organic matter is rapidly metabolized with the colloidal organics adsorbed onto the surface. As the biota die, they are discharged from the filter with more or less partly decomposed organic matter.
This sloughing off of material may occur periodically as in a standard rate filter or continuously as in a high rate filter.

The essential features necessary to the process are:

1. Sufficient surface area must be provided for biologicalgrowth.
2. Free oxygen must be available at the surface to replenish the dissolved oxygen extracted from the liquidlayer.
3. Sewage, and in particular industrial wastes must be amenable to biological treatment.

**Construction**

A trickling filter consists of a bed of crushed stone or other non-disintegrable contact material viz., granite, limestone etc.,
25 cm and 75 cm in size, with the filter depth usually between 2 and 3 m. The larger stones 8 cm - 10 cm. in size are placed in a layer 15 cm - 20 cm thick at the bottom of the bed, while the smaller size stones 2.5 cm size make up the filter bed. The Inside walls of brick masonry may be honey combed (with the idea of securing better aeration of the beds) and provided with airinlets.
In such a filter, air must circulate freely so as to maintain the zooleal flora, which thrives over the stones in the presence of oxygen. The sewage from the sedimentation tank is applied either intermittently through fixed sprays located at the surface of the bed or by what is more favored, i.e., applying sewage continuously through rotary distributors. A rotary distributor consists of two or more arms which are turned in a horizontal plane through the jet action, or sometimes when it is insufficient, moved by the electrical power. The spray nozzles are circular holes 9 mm - 13 mm, and spaced in such a manner that the distribution of applied sewage is more or less in direct proportion to the area of the bed covered by each part of the distributor.

The floor of the trickling filter is made of concrete laid to a slope of 1 in 200. It has a system of underdrains, half-round or v-shaped channels cast into it and making a false bottom with perforated cover to support the coarse media above. The underdrainage system keeps the filter self-cleansing and also assists in the ventilation of beds.

**Merits and demerits**

The advantages of trickling filters are:

1. They are self-cleaning. Rate of filter loading is much higher.
2. No diminishing of capacity even if overdosed, they can recoup after rest.
3. They are cheap and simple in operation.
4. Mechanical wear and tear is very small.

The disadvantages are:

1. High head loss through the filter, making automatic dosing of filters as necessary.
2. Odor and fly nuisance due to psychoda which may be carried away into human habitation and may prove a serious nuisance to man. The latter may be overcome by flooding the filter or by the use of DDT or other insecticides.
3. Large land area is required. Cost of construction is relatively higher.
4. They require preliminary treatment and, therefore, cannot treat raw sewage as such.

I hope this comparitive study of the different components of the microbiological wastewater treatment plant provides the right guidance for your plant.

Before I sign off today, I'd like to ask you to take a closer look at the All About Wastewater Treatment (Institutional/ Corporate Edition) eBook, the contents of which are described at

allaboutwastewaterandtreatment.com



This is the book with literally hundreds of 'word of mouth' tips and methods- secrets which are next to impossible to find in books
- the gold which only comes from years and years of hands on experience ... including all the hard to find Wastewater Treatment tips and information that people just can't locate with internet searches or trips to the library. For your Institution, this book will be of interest as it would provide you with information as to where to buy the equipment and which theory to follow for the treatment of wastewater at the best price. Detailed information on the different treatment methods as well as basic theories employed for the treatment are also given in the book. This book also gives an insight on How To Run the Wastewater Treatment Plant Effectively and Efficiently.


"Everything you really need to know about Wastewater treatment all, in one place!"

From the Desk of Richard Runion and TEAM

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january 08, 2008 03:09pm

immobilized cell oxidation process

Today, we'll talk about advanced
wastewater treatment technology.
Let's begin.

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Amongst the advanced technologies, immobilized cell oxidation process has been used more successfully for the treatment of wastewater. Immobilized cells have been defined as cells that are entrapped within or associated with an insoluble matrix. Mattiasson discussed six general method of immobilization: covalent coupling, adsorption, biospecific affinity, entrapment in a three dimensional polymer network, confinement in a liquidliquid emulsion, and entrapment within a semi permeable membrane.

Under many conditions, immobilized cells have an advantage over either free cells or immobilized enzymes. By preventing washout, immobilization allows a high cell density to be maintained in a bio-reactor at any flow rate. Catalytic stability is greater for immobilized cells and some immobilized microorganisms tolerate higher concentration of toxic compounds than do their non-immobilized counterparts.

One partial disadvantage of immobilization is the increased resistance of substrates and products to diffusion through matrices used for immobilization. Owing to the low solubility of oxygen in water and the high local cell density, oxygen transfer often becomes the rate limiting factor in the performance of aerobic immobilized cell systems. Thus when aerobic cells are used, aeration technique bears a very important consideration in bioreactor design technology

Advanced 'Immobilized Cell Reactor' employing aerobic cells, has been recommended for the treatment of tannery wastewater. This technology comprises of immobilization of chemo-autotrophs, oxidation of dissolved organics in water and filtration of treated water. The activated carbon serves as a matrix to facilitate selective solute transfer, enhanced bio film attachment or restricts the permeation of microorganisms to the downstream.

**Advanced 'Immobilized Cell Reactor' technology for treatment of wastewater**

The concepts reinforced in this technology are:

1. immobilisation of organisms in the carrier matrix will prevent 2. accessibility of enzymes to the substrate is increased by reducing the mean free path of the bio catalyst to the substrate 3. reduce the cellular synthesis by using the organisms with low-yield coefficient

In Advanced 'Immobilized Cell Reactor' technology, the carrier matrix used is activated carbon of low surface area. The characteristics of carbon is presented in table 1. The bacteria immobilized in anoxic zone can fragment the organics into simpler compounds and the bacteria in oxic zone perform oxidation of organics. In addition to bacterial oxidation, catalytic oxidation is also facilitated at the active sites of the carbon matrix. The heat of combustion of organics released at the active sites will be used for excitation of organic molecules to cross over the activation energy barrier, which normally determines the rate of any chemical reaction.

The freedom of movement of molecules is also restricted at the surface of adsorbent as they are anchored at the sites. Thus energy expenditure towards translational motion, which is considered to be the major component in the orientation of molecule, is lowered to maximum extent. The partially oxidized organic molecule is aerobically oxidized with low heat of combustion by aerobic organisms immobilized at the mouth of the pores. Thus, the energy available for cellular synthesis is decreased and consequently the biomass production is decreased. Since the organisms are in immobilized state, the expenditure of energy towards diffusion of organic molecules and oxygen from the bulk liquid to cellular matrix is very minimum compared to that in suspended growth system.

Hence, the conservation of energy in the immobilized state, enhances the rate of degradation of organics in wastewater is much greater than in suspended growth system. The elimination of micropores in the carrier matrix avoids the loss of active sites by irreversible bonding with organic molecules in aqueous environment.
Therefore, the number of active sites available for oxidation of organic compounds remains a constant. Thus, the rate of removal of dissolved pollutants in wastewater is nearly constant.

Merits and demerits of Advanced 'Immobilized Cell Reactor'
technology:

The treatment of domestic wastewater through Advanced 'Immobilized Cell Reactor' system has many advantages as listed below: Less land requirement Less electrical and mechanical equipment Less detention period (1 - 4 hrs.) Less power consumption (about 30% of the conventional consumption) Aeration tank is not required No foaming problem No addition of micro / macro nutrients No biomass production No secondary settling Tertiary treatment is not required Positive response to achieve discharging standards (BOD < 30 mg/l, COD < 250mg/l) Complete removal of color and odor Possibilities to reuse the treated effluent Provisional to handle the additional load by adding more number of modules Need not work on holidays Treated effluent can be used for agricultural / recreational purposes Investment cost for domestic wastewater treatment is only
75 % of the conventional one Payback period of Advanced 'Immobilized Cell Reactor' system is 26 months towards savings on electrical power and chemical consumption The treated wastewater supports the growth of vegetative plants

Demerits of Advanced 'Immobilized Cell Reactor' technology

Permeability is less than that of sand filters Maximum organic loading rate allowed is only 1.2 kg 2 COD/m of Advanced 'Immobilized Cell Reactor' reactor. Performance of Advanced 'Immobilized Cell Reactor' reactor is limited by the presence of suspended solids in wastewater. Anaerobic treatment is an essential unit of operation before proceeding to Advanced 'Immobilized Cell Reactor' reactor. This is to reduce the viscosity of wastewater and eliminate colloidal solids. Multiple modules is required to handle huge volumes instead of a single module.

The same advanced immobilized cell reactor technology can be used in different industries like leather, textiles, sago, chemicals, pharmaceticals, domestic water treatment, etc.

Before I sign off today, I'd like to ask you to take a closer look at the All About Wastewater Treatment (Institutional/ Corporate Edition) eBook whose contents has been described at allaboutwastewaterandtreatment.com
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january 03, 2008 03:31pm

Wastewater Daily Discussion - Stabilizat

Expert 'Tip & Tricks' from out friends at all-about-wastewater-treatment.com

Several factors may significantly affect or aid, the hydraulic and biological behavior of waste stabilization ponds. Some, not all, can be taken care of during design.

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**Wind**

Ponds should be designed to induce churning by wind. We know, this results in uniform distribution of BOD, DO, algae and microorganisms all through the depth of water. It also moves oxygen down. This is particularly important when there is nil or insufficient photosynthetic activity. On the flip side, strong winds may produce high waves and erosion to the embankment slopes.

**Temperature**

Temperature directly influences the physical, chemical and biological activities in a pond system. Rate of photosynthesis and cellular metabolism are directly proportional to the pond temperature. Ponds should be designed for most adverse temperature conditions. At lower temperature, dissolved oxygen present has a tendency to remain in pond longer. As the temperature rises, dissolved oxygen is likely to be liberated to atmosphere, especially under supersaturated conditions. The oxygen production by Algae through photosynthesis is also temperature dependent. All ponds perform well on a sunny, cloudless day at an air temperature above 20 deg C and mild wind conditions. At a temperature above 35 deg C, the rate of photosynthesis declines rapidly and at temperatures above 45 deg C, it altogether stops. High temperatures stimulate growth of bluegreen algae at the expense of more efficient green algae. At the same time, aerobic bacteria consume oxygen at higher rate creating conditions to form anaerobic patches in the pond. Sudden reduction in temperature slows down algae activity and oxygen production. Algae will move to lower layers, the green color will reduce and pond performance will drop.

**Rainfall**

Rainfall influences pond performance. Detention time reduces when it rains. Besides, heavy shower dilutes the contents of shallow ponds reducing the food available to biomass. Rainfall adds oxygen to a pond system by increasing turbulence.

**Solar radiation**

Solar radiation directly relates to photosynthesis by the algae.
However, the rate of increase of photosynthesis declines when radiation intensity exceeds certain limits. Oxygen production also reaches a constant level. Actually, light is the factor for oxygen production in low light intensity conditions. And temperature is the guiding factor in areas of high light intensities. Latitude of the location and mean sky clearance factors help in determining the light intensity throughout the year. So, these are important parameters in designing the pond system, particularly the facultative pond. Too much solar radiation has adverse effects on pond performance.

**Evaporation and seepage**

These causes excessive loss of water resulting in increase in solid concentration which upsets the ecological balance. An evaporation rate in excess of 5 mm depth per day (50 cubic m)/hectare/day water
loss) is excessive and needs special attention. Soil characteristics along with knowledge of ground water, hydrology are important when selecting the site. If ponds have to be built on permeable soils, they must be lined to minimize seepage.

Physical factors:

**Surface area**

The surface area is a function of organic loading (BOD ) applied 5 per day (especially in case of facultative ponds). In warmer climates, surface loading from 150 - 400 kg BOD has been successfully deployed, though exceeding 250 kg BOD may cause odor problem.

**Water depth**

Stabilization ponds operate at constant depth as designed. Depths, less than 0.9 m cause growth of aquatic plants, surface weeds and mosquitoes. Depths exceeding 2 m in facultative ponds may limit sunlight penetration. So, anaerobic condition at the bottom layer may be created. A design depth of 1.5 m in facultative ponds has shown good results.

**Short circulating**

Incorrect positioning of inlet and outlet and poorly shaped ponds may produce short-circulating (dead or stagnant zones) within the pond. They may also transport the incoming wastewater quickly to the outlets, thus affecting pond performance.

Chemical factors:

**pH value**

Anaerobic and facultative ponds work well under slightly alkaline condition. So, industrial wastewater with high pH values should be appropriately controlled at the source before entry to ponds.

Anaerobic ponds situated in warm climates are usually biased to an alkaline pH value. In facultative ponds, if the pond turns deep green, the pH value can be taken to be in the alkaline range. If the pond water is yellowish green or milky, it is acidic.

However, facultative ponds display a natural diurnal variation in pH value. In the mornings, the pH value is low, due to excess carbon dioxide while in the late afternoon, the pH value rises due to the consumption of carbon dioxide by algae.

Before I sign off today, I'd like to ask you to take a closer look at the All About Wastewater Treatment (Institutional/ Corporate Edition) eBook whose contents has been described at

AllAboutWasteWater.com

This is the book with literally hundreds of 'word of mouth' tips and methods- secrets which are next to impossible to find in books
- the gold which only comes from years and years of hands on experience ... including all the hard to find Wastewater Treatment tips and information that people just can't locate with internet searches or trips to the library. For your Institution, this book will be of interest as it would provide you with information as to where to buy the equipment and which theory to follow for the treatment of wastewater at the best price. Detailed information on the different treatment methods as well as basic theories employed for the treatment are also given in the book. This book also gives an insight on How To Run the Wastewater Treatment Plant Effectively and Efficiently.

january 01, 2008 11:45pm

Wastewater Daily Discussion -

Expert 'Tip & Tricks' from out friends at all-about-wastewater-treatment.com

Today feed is about Toxicity factors that affect pond performance
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**Toxic materials**

Stabilization ponds are generally immune to toxic substances and heavy metals. Long detention time allows gradual absorption of the inhibiting substances by the existing biomass, provided there is no shock load. Concentration of 6 mg/l of each of heavy metals like cadmium, chromium, copper, nickel, zinc has not affected the treatment efficiency in a facultative ponds

**Oxygen**
Dissolved oxygen (DO) helps to identify the efficiency of operation in a facultative or maturation pond. A normally functioning facultative pond will be supersaturated with free oxygen at the surface and in the sub - surface layers during the afternoon.
However, DO concentration may reduce to below 1.0 mg/l or even zero at dawn. The aerobic (the one that absorbs oxygen) surface layer strips off odor release in wellmaintained ponds.

**Heavy metals**

Heavy metals do not cause a problem with domestic wastewater since ponds can withstand upto 30 mg/l of heavy metal without any reduction in treatment efficiency.

**Algae and bacteria**

The performance of a pond system directly depends on its constituent algae and bacterial population. Presence of any toxic substance that affects their metabolism will reduce their performance. The algae are more easily affected than the bacteria.
In ponds treating domestic wastewater, the major toxicants are ammonia and sulfide.

**Effect of ammonia**

If ammonia concentration exceeds 28 mg/l, algae may manage if ponds are within pH range during daylight hours. Ammonia is exponentially more toxic above pH 8, since a larger proportion is then in the unionized state, so can rapidly penetrate the algae cell and inhibit photosynthesis. This can cause the facultative pond to behave like an anaerobic one, even when the BOD surface loading is low. However, this can be reversed in a few hours. Inhibition of photosynthesis also reduces pH and hence toxicity of ammonia.

**Effect of sulfide**

Sulfide is toxic to algae in its H(subscript)2S stage. Its toxicity increases when pH decreases. In the normal range of pH in ponds, when sulfide concentration exceeds 8 µg/l, the activities of anaerobic heterotrophic bacteria are inhibited. Concentration of 50
- 150 mg/l inhibits methanogenesis in anaerobic ponds.

Before I sign off today Bob, I'd like to ask you to take a closer look at the All About Wastewater Treatment (Institutional/ Corporate Edition) eBook whose contents has been described at
AllAboutWastewater.com



This is the book with literally hundreds of 'word of mouth' tips and methods- secrets which are next to impossible to find in books
- the gold which only comes from years and years of hands on experience ... including all the hard to find Wastewater Treatment tips and information that people just can't locate with internet searches or trips to the library. For your Institution, this book will be of interest as it would provide you with information as to where to buy the equipment and which theory to follow for the treatment of wastewater at the best price. Detailed information on the different treatment methods as well as basic theories employed for the treatment are also given in the book. This book also gives an insight on How To Run the Wastewater Treatment Plant Effectively and Efficiently.
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