The treatment techniques are as specified by relevant regulatory bodies to reduce pathogen (disease causing organisms), reduce vector (flies, rodents, etc.) attraction and stabilize metals. Treatment is usually dewatering, or thickening followed by alkaline stabilization, heat treatment, composting, aerobic or anaerobic digestion or chemical conditioning.

The resulting biosolids product may be used on agricultural lands as nutrient augmenting products, enhancing soil properties with the aim of increasing crop growth. However the extent of land application depends on the conformance of the biosolids to stringent regulatory criteria, as shown in the Tables 1 and 2. Pollutant loading also influences the application rate. For example, the amount of a nitrogen-rich biosolids that is applied per hectare of agricultural land will depend on the nitrogen already present in the soil and what is required by the specific crop, in order to not apply more than the agronomic rate (what is necessary for optimal plant growth while minimizing the amount reaching groundwater). Moreover, the biosolids applied must be monitored based on the amount applied, from once a month to once a year, for pollutants, pathogen and vector attraction reduction.

The two major problems associated with land application of biosolids are unpleasant odor and the risk of non-point source of pollution through runoff. Odor aesthetically affects persons living near biosolids application sites. It is due to the emission of volatile gases during chemical and microbial degradation of organic matter in the biosolids. The main odorous substances emitted from biosolids are ammonia and sulfur compounds.

Odor emissions can occur at the biosolids treatment and storage stages. Incomplete treatment causes odors; for example, low retention time during aerobic digestion or poor aeration during composting. The solution is to ensure complete and effective treatment with frequent monitoring of treatment and indicator parameters. At the storage stage, high humidity, hot weather, precipitation (rain or snow), drop in pH and low oxygen level cause the formation of odors. It is important to minimize the storage period as well as monitor for odors continuously. Microbial degradation can be avoided short term by liming during storage. Knowing the prevailing wind direction can aid in preventing the dispersion of odors by means of storage location selection or effective barriers. Ensuring that the biosolids are kept away from any water sources is also important. Constructing structures to eliminate rain water from reaching biosolids is essential.

The application of biosolids to land poses a risk of non-point source of pollution to surface water and groundwater. Runoff events (rain or snow) can cause biosolids to reach water bodies. Groundwater under the direct influence of surface water is also vulnerable. Typical contaminants include the nutrients phosphorus and nitrates, boron, sodium and pathogens. Nutrient loading to water bodies may lead to excessive growth of algae. Pathogen present may results in sicknesses in humans such as gastrointestinal diseases. Emerging pollutants of concern include endocrine disruptors (dioxins, pesticides, etc.), pharmaceuticals (birth control pills, antibiotics, etc.) and flame retardants, and the impacts of these chemicals on human health and the environment are being investigated in wastewater discharges.

The nutrient loading to water bodies may be controlled by applying biosolids to land as per the agronomic rate of a crop (thus minimizing the nitrogen that may find its way to groundwater). Runoff as a non point source of pollution may be controlled by maintaining distances of the stored biosolids to water bodies as per regulatory requirements and constructing barriers. The slope of the land, soil permeability and proximity to a surface water or groundwater well are factored in when determining the regulatory requirements of distances to water bodies. Barriers that are constructed to provide a physical means of runoff control are roofs, side walls, dykes and runoff containment ponds.

To summarize, the benefits of land application of biosolids include recycling of a waste product (sewage sludge) and providing plant nutrients cost effectively. Issues include odor and risk of surface and groundwater pollution which may be eliminated with a case-specific biosolids management plan in place. With correct treatment and storage techniques including an effective runoff prevention design, odor problems may be eliminated and the pollution of water bodies may be prevented.

References

National Research Council (NRC) (2003). ‘Biosolids Management Program’. A Best Practice by the National Guide to Sustainable Municipal Infrastructure.

National Research Council and Federation of Canadian Municipalities (NRC and FCM) (2005). ‘Quality Management for Biosolids Program’. A Best Practice by the National Guide to Sustainable Municipal Infrastructure (Infraguide).

United States Environmental Protection Agency (2003). Environmental Regulations and Technology. Control of Pathogens and Vector Attraction in Sewage Sludge. Document #EPA 625/R-92/013.

The proposed site for investigation is a pesticide plant belonging to a multinational organization founded in 1980. The plant spans in 50 acres in area, situated in an industrial site 25 miles from urban environment. The plant was used to manufacture pesticides and also served as a distribution hub. Operations at site included manufacture of pesticides, storage of chemicals and repackaging of chemicals from railcars and drums. The waste generated in the process was disposed in discharge ponds.

On 3 December 1984, one of the storage containers leaked letting out a thick cloud containing a mixture of methyl isocyanate (MIC) (toxic gas, lethal, highly irritant), chloroform, volatile organic carbon (VOC) and hydrochloric acid (HCl). The MIC, an intermediate product used to make carbaryl, wafted through the atmosphere and killed 8000 people, affecting hundred thousand more – mostly through inhalation & skin contact. Due to this, the plant was shut down and the site was placed under national priority list (NPL) – a published list of hazardous waste sites.

A Government agency was interested in determining the level of contamination and needed an investigation plan to be done to determine the level of contamination at the site. The activity of formulating an investigation plan was given to a private contract.

The purpose of the contract was to provide level of impact caused by the leakage of gases on the environment (air, water and soil), the impact caused by the disposal of chemical to the lagoons (ground water contamination) and measures to be taken to avoid the potential harm to surrounding environment.

The work of this contract includes labor and equipment requirement for conducting the required air monitoring, ground water sampling, well monitoring, and soil sampling.

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Recent discovery of life deep in the sea, miles below the surface of the ocean, amidst extremely high temperatures thwarts all basic learning we have had to date on the energy sources that drive life. Science that led us to believe that light, oxygen, etc. were required for life, no longer holds good with the discovery of life – six foot, red tipped tube worms, larger white clams, yellow mussels and pale crabs – all living miles below the surface of the water where volcanically heater water seeps through the sea floor. Some see this as proof for the first time that the earth could sustain life itself.

These questions & their findings led scientists to dive deep into the sea to understand what energy source fuels these lives and what adaptations allow them to exist in such harsh environments.

Evolution of Hydrothermal Vents & Hydrothermal Communities

Hydrothermal vents are deep-sea hot-springs where thermal (volcanic) activity generates super-hot, mineral-rich water. Seawater seeps down deep into the earth’s crust through cracks and fissures in the ocean floor. This water is then heated by the intense heat of magma below the surface. As the water is heated to a boil, it expands and rises back to the surface. On its way back up through the cracks and fissures through which it flowed, the hot water dissolves minerals and other chemicals from the rock. The hot fluid flows into very cold water and cools down quickly. The cooled minerals in the fluid settle around the vent opening creating chimney-like formations. The temperature of the water coming out of these vents exceeds 400º C.

These hydrothermal processes have been predicted. What was unpredicted and created quite the scientific stir was the existence of thriving communities of life forms at these sites. These hydrothermal vents support extraordinary ecosystems deep beneath the surface of the oceans. These ecosystems are the only communities on Earth whose immediate energy source is not sunlight. So how do living things survive in such an environment? The answer is found in bacteria that can use another source of energy to make food.

Water coming out of a vent is rich not only in dissolved minerals but also in Chemosynthetic bacteria. These bacteria are capable of utilizing sulfur compounds to produce organic material through the process of Chemosynthesis. They feed on inorganic compounds to obtain energy and are hence termed as Chemolithotrops. The sulfide or other inorganic energy sources emerging in hydrothermal solution that chemolithotrophs at these vent sites use are formed via the interaction of seawater with basalt at the high temperature and pressure 1 to 3 km below the ocean floor. These chemolithotrophs form the basis of the ecosystem around the vents. All other vent animals ultimately depend on this bacterium for food.

Challenges posed by the discovery of hydrothermal community

The finding of life and an independent ecosystem in such harsh non-light conditions have challenged our understanding of the physical & biochemical constraints on the limits for creation or existence of life and stimulates new theories on the origin of life. The most astounding discovery from the study on life around hydrothermal vents is that, life could exist on thermal and chemical energy as opposed to just sunlight and that photosynthesis was not the only way to support life.

Extensive efforts are underway to establish a link between the hydrothermal communities and the potential origin of life. Some of the major researches underway on this are

*The New Millennium Observatory 1998 expedition aboard the NOAA research ship

*National Science Foundation- funded expedition led by Scripps Institution of Oceanography’s Donna Blackman, UW’s Kelley and Duke University’s Jeffrey Karson. Blackman and Karson

*National Science Foundation- funded project LARVE, to understand how vent species colonize new vents, and what controls their distributions over regional and global scales.

Their findings began a dramatic shift in the thinking of the biologists studying the origin of life.

Did life begin in hydrothermal vents? The theory claims that living systems originated in so-called “inorganic incubators” – small compartments in iron sulphide rocks. Some researchers have proposed that life began in submarine hydrothermal vents, where superheated subterranean water pours into the sea. The idea is that the heat can help synthesize polymers, which would then be quenched in the surrounding seawater — this would prevent the same energy from destroying the products soon after they were formed.

Some interesting theories on the origin of life propose that rather than the building blocks of life originating first and then forming themselves into cells they believe that cells came first. They say that the first cells were not living cells but inorganic ones made of iron sulfide and were formed not at the Earth’s surface but in total darkness at the bottom of the oceans.

Five researchers in Nagaoka, Japan, claimed to have simulated such conditions in a flow reactor, using the simplest amino acid, glycine. And the most complex molecule their ‘simulation’ produced was hexaglycine, in the microscopic yield of 0.001%. Compared to the complexity of even the simplest living cell, hexaglycine is extremely simple. High temperatures would degrade any complex molecules over the alleged geological time. Hence eminent scientists are not open to considering the findings of the study as a proof of origin of life.

The questions that arise from the thriving of these deep-sea communities are seemingly infinite. Research continues to find the link between the life around hydrothermal vents & the origin of life. One thing is sure. Hydrothermal vents gave us a changed view of “life” and a new understanding of Earth.

References

*Zierenberg, A. Robert., Adams,W.W.,Michael. and Arp,J. Alissa (2000) Life In Extreme Environments: Hydrothermal Vents, pp1-2,Vol 97,no 24

*Sarfati Jonathan (2002) Creation Ex Nibile Technical Journal, Vol. 13, No.2

*Russell ,J.M., Hall. A.J.,Jour. and Geol. (1997) The Emergence of Life From Iron Monosulpfide Bibbles At A Submarine Hydrothermal Redox and PH Front, Vol 154, pp 377-402

The pharmaceutical industry generates process wastewaters containing various pollutants, which depend on the nature of processes by which the products are produced. Most pharmaceutical substances are manufactured utilizing batch processes; at the end of a manufacturing batch, another pharmaceutical intermediate or substance is made, thus generating different waste streams. For specific pollutants that do not get removed by physico-chemical and biological treatment, such as recalcitrant toxics such as volatile organic compounds (VOCs) and for bioinhibiting substances such as sulfur and cyanide, other advanced treatment technologies have been developed. The suitability of each to a particular pharmaceutical wastewater is assessed by treatability studies, many of which are recorded in literature.

Studies on the feasibility of membrane treatment for pharmaceutical effluents describe how this technology could eliminate typical activated sludge process (ASP) problems by accomplishing liquid-solid separation and biodegradation within the reactor (avoiding secondary clarification), having a control on F/M ratio (less sludge produced), doing away with recycle pumps (consuming less power), and removing almost all suspended solids (SS) with the microporous membrane (Benitez, et al., 1995, and Freitas dos Santos and Biundo, 1999).

Extractive membrane bioreactors (EMB) are documented extensively for destroying toxic VOCs by a combined step of membrane extraction and biodegradation of the permeate by specially cultured biomedium in a mixed and aerated reactor (Livingston et al., 1998). A typical EMB employs hollow fibre membranes consisting of many tubular membranes encased in a cylindrical shell; rarely are flat plate membranes used. Freitas dos Santos and Biundo (1999) conducted treatability studies on pharmaceutical wastewater contaminated with dichloromethane (DCM) with no pre-treatment or dilution. Their laboratory-scale EMB removed 95% of DCM, which is indeed impressive. Freitas dos Santos and Livingston (1995) have reported similar removal success of 1,2 dichloroethane (DCE) from synthetic wastewater, and mathematically analysed mass transfer and biofilm diffusion and reaction.

Hollow fiber membrane reactors (HFMR) themselves are used to remove pollutants from pharmaceutical wastewaters. Aziz et al. (1995) conducted studies on an HFMR to treat wastewater contaminated with trichloroethane (TCE). At influent concentrations between 120 to 709 µg/L, 81.0 to 95.3% TCE was removed from the lumen (inner) side of the membrane and passed to the biomedium on the shell side where 77 to 88% TCE was biodegraded. In a similar study on pharmaceutical wastewater with high COD (more than 1000 mg/L) Benitez et al. (1995) used a bench scale HFMR. Wastewater was filtered through the membrane radially by suction in, interestingly, intermittent cycles and average COD removal efficiency was only 68%.

Before reiterating that membrane bioreactors could be the answer to ASP difficulties, it is necessary to assess their method, performance and costs. From literature, it is clear that the membrane performance depends on the mass transfer coefficient and membrane-aqueous partition coefficient; different operating parameters and applications result in varying coefficients (Gabelman and Hwang, 1999, and Semmens and Gantzer, 1994) and membrane performances (Min and Hwang, 1999). Reported membrane-aqueous partition coefficients are greater than 1 and according to Brookes and Livingston (1995), they are amenable to extraction. However, mass transfer coefficients reported are low compared to economically optimum values of, according to Livingston et al. (1998), 1 to 5 *10-5m/s. Mathematical modeling by Freitas dos Santos and Livingston (1995) helped pinpoint the cause of limited mass transfer as being the accumulation of pollutant at the membrane-biofilm interface, while Aziz et al. (1995) construed from their modeling exercise that the film resistance on both sides of the membrane are equal and strongly affect mass transfer rate while the membrane resistance itself is negligible. Thus mathematical modeling of the mass transfer as well as biodegradation processes proves useful to improving the process efficiency.

Extractive membrane bioreactors hold great promise in destroying VOCs but very high capital costs seem to hinder practical application. The gap between bench scale studies and actual application has to be bridged by corroborating the small-scale results with scale up pilot plant studies. Given the highly variable nature of the pharmaceutical effluent, it is not possible to come up with a common treatment plant design. However, with more investigations being done into the treatment of various types of pharmaceutical industry effluents, the prospects of arriving at technologically acceptable and economically feasible treatment alternatives seems good, given time and extensive research.

References

*Aziz, C.E., Fitch, M.W., Linquist, L.K., Pressman, J.G., Georgiou, G., and Speitel, Jr. G.E. 1995. Methanotrophic biodegradation of trichloroethylene in a hollow fiber membrane bioreactor. Environmental Science and Technology. 29, pp. 2574–2583.

*Benitez et al. 1995. Stabilization and dewatering of wastewater using hollow fiber membranes. Water Research, 10, 2281-2286.

*Brookes, P. R. and Livingston, A. G. 1995. Auqeous-aqueous extraction of organic pollutants through tubular silicone rubber membranes. Journal of Membrane Science, 104, 119.

*Frietos dos Santos, L. M., and Biundo G. L.1999. Treatment of pharmaceutical industry process wastewater using the extractive membrane bioreactor. Environmental Progress, 18, 34-39.

*Frietos dos Santos, L. M., and Livingston, A. G. 1995. Novel membrane bioreactors for detoxification of Voc wastewaters: biodegradation of 1,2-dichloroethane. Water Research, 29, 179-194.

*Gabelman and Hwang, 1999. Hollow fiber membrane contactors. Journal of Membrane Science, 159 (1-2), 61-106.

*Livingston, Arcangeli, Boam, Zhang, Marangon, Freitas dos Santos, 1998. Extractive membrane bioreactors for detoxification of chemical industry wastes: process development. Journal of Membrane Science, 151, 29-44.

*Min, L., and Hwang, S. K., 1999. Correlation of concentration polarization and hydrodynamic parameters in hollow fibe r modules. Journal of Membrane Science, 159 (1-2)143-165.

*Semmens, M.J., Gantzer, C.J. 1994. Gas transfer without bubbles, Proceedings of the ASME Fluids Engineering Division Summer Meeting, Pt. 9, Lake Tahoe, NV, 51–58

Methane is both a potential alternative energy source and a potent greenhouse gas. Methane is emitted during the production and transport of coal, natural gas, and oil. Methane emissions also result from the decomposition of organic wastes in municipal solid waste landfills and livestock, mostly cows. Methanogenic bacteria in the ruminants’ digestive tract are a major cause of this gas, with cows providing the single largest source.

Impact of Methane on Global Warming

Each greenhouse gas differs in its ability to absorb heat in the atmosphere. Methane traps over 21 times more heat per molecule than carbon dioxide and is expected to cause between 15 and 17% of the global warming over the next 50 years (Adam, 2000).

As per a report by Dr. S.N. Singh from NBRI, India on Perturbing the Heat Radiation Balance of the Earth, the livestock and associated manure management also contribute about 16% of total annual production of methane. These emissions are the direct result of digestion of fibrous grasses in the rumen of the animals. Cows account for about 80% of the global annual CH4 emissions from domestic livestock. This would mean that cows account for 12.8% of the total annual production of methane.

Role of Cows in Methane Production

Methane (CH4) is released by livestock as a by-product of digestion. The breakdown of carbohydrates in the digestive tract of herbivores (including insects and humans) results in the production of methane. (Adam, 2000). The initial steps are performed either by facultative anaerobic bacteria (such as E. coli which convert formate to H2 and CO2) or by obligate anaerobes (Clostridium or Selenomonas which do similar conversions). Methanogenic archae bacteria (a group separate from true bacteria) are obligate anaerobes that are very sensitive to oxygen and prefer environments without any other electron acceptors such as nitrogen (Beckmann, 2000; College, 1999). They perform the final steps in the fermentation and they convert H2 and CO2 produced by the other organisms to methane or they can convert acetic acid to methane. Approximately, 90 – 95% of the CO2 produced is converted to methane, and the energy derived is used to fix the remaining CO2 into cellular materials. Strictly speaking, this methane formation action by the methanogens is not a fermentation (as there is no substrate level phosphorylation and ATP is generated via the methane formation pathway), but is rather a strange form of respiration.

These methanogens are present in ruminant animals other than cows, such as sheep and wildebeest. Approximately, 10 percent of humans have these methanogens in their guts as well, probably inherited from their parents (Beckmann, 2000).

It has been estimated that 9 to 12% of the energy that a cow consumes is turned to methane that is released either through flatulence or burping. A number of factors affect methane emission, including diet, barn conditions, and whether or not the cow is lactating, but an average cow in a barn produce 542 liters of methane a day and 600 liters when out in a field (Adam, 2000).

As per a report by Dr. S.N. Singh from NBRI, India on Perturbing the Heat Radiation Balance of the Earth, the livestock and associated manure management also contribute about 16% of total annual production of methane. These emissions are the direct result of digestion of fibrous grasses in the rumen of the animals. Cows account for about 80% of the global annual CH4 emissions from domestic livestock. This would mean that cows account for 12.8% of the total annual production of methane.

Role of Cows in Methane Production

Methane (CH4) is released by livestock as a by-product of digestion. The breakdown of carbohydrates in the digestive tract of herbivores (including insects and humans) results in the production of methane. (Adam, 2000). The initial steps are performed either by facultative anaerobic bacteria (such as E. coli which convert formate to H2 and CO2) or by obligate anaerobes (Clostridium or Selenomonas which do similar conversions). Methanogenic archae bacteria (a group separate from true bacteria) are obligate anaerobes that are very sensitive to oxygen and prefer environments without any other electron acceptors such as nitrogen (Beckmann, 2000; College, 1999). They perform the final steps in the fermentation and they convert H2 and CO2 produced by the other organisms to methane or they can convert acetic acid to methane. Approximately, 90 – 95% of the CO2 produced is converted to methane, and the energy derived is used to fix the remaining CO2 into cellular materials. Strictly speaking, this methane formation action by the methanogens is not a fermentation (as there is no substrate level phosphorylation and ATP is generated via the methane formation pathway), but is rather a strange form of respiration.

These methanogens are present in ruminant animals other than cows, such as sheep and wildebeest. Approximately, 10 percent of humans have these methanogens in their guts as well, probably inherited from their parents (Beckmann, 2000).

It has been estimated that 9 to 12% of the energy that a cow consumes is turned to methane that is released either through flatulence or burping. A number of factors affect methane emission, including diet, barn conditions, and whether or not the cow is lactating, but an average cow in a barn produce 542 liters of methane a day and 600 liters when out in a field (Adam, 2000).

Reduction of Methane Production

It has been suggested that reducing methane production is much more economical as methane emissions are not economically necessary (DeCorla-Souza, 2001).

Suggestions of ways to reduce this production include genetically engineering cattle, the bacteria they carry that produce the methane or altering their feed. Improved management of animals in extensive grazing systems and protected feeds are other suggestions aimed at reducing methane production. The duel aims of all of these methods are to reduce methane production at the same time as increasing production.

Altering their feed seems to be the easiest course and can either be by means of feeding the cattle less “volatile” fodder (Radford, 2001) or by adding substances to the feed. The addition of a bacterium to cattle feed has shown some small scale success. Bacteria uses oxygen to convert methane into carbon dioxide and in doing so, it stimulates the microbial activity in the animal’s gut that aids the digestive processes thus leading to a more productive cow (Chang, 2000).

Conclusion

Most people associate methane (CH4) with harmful greenhouse gas, but it may also serve as a fuel source for electrical energy. Optimistic Science sees Methane as (1) Greenhouse Gas (2) End Product of Carbon Cycle (3) Important Fuel
With the strong focus by environmentalists on reducing CO2, it seems that methane emission reduction has been pushed aside, when it could be an easier, quicker and cheaper method of reducing greenhouse gases (DeCorla-Souza, 2001).
As science advances to find cheaper and efficient ways to generate energy from methane, we will have far more control on managing the production and use of methane thereby controlling its effect on global warming.

References

*Eddy,Metcalf. 2003. Waste water Engineering Treatment and Reuse, pp 631-633, Tata McGraw-Hill Publishing Company Limited, New Delhi.

*Adam, D. 2000. Tracking methane emissions from cows just got a little easier, URL: http://www.nature.com/nsu/000907/000907-6.html ,date: Sep 5, 2000

*Kaharabata, S. K., Schuepp, P. H., & Desjardins, R. L. 2000. Estimating methane emissions from dairy cattle housed in a barn and feedlot using an atmospheric tracer. Environmental Science and Technology 34, 3296 – 3302.

*Anonymous: Howis Seranne. Cow flatulence: a significant contributor to global warming or just a load of hot air. Rhodes University, Department of Botany, Grahamstown, 6140.

*Anonymous: Beckmann, R., Beans means methane for some. CSIRO publishing, URL: http://www.publish.csiro.au/ ecos/Ecos88/Ecos88B.htm , date: 2000.

*Anonymous: Singh, S. N. Perturbing the Heat Radiation Balance of the Earth. Report, NBRI, India.

Wastewater treatment plants in cities experiencing population growth and restricted by space for expansion are increasingly adopting alternatives like modified activated sludge (AS) systems. Emerging technologies among the alternatives include integrated fixed film/activated sludge (IFAS) and moving bed biological reactor (MBBR) systems.

Systems such as IFAS and MBBR involve the addition of floatable plastic media into existing AS basins to provide active sites for biomass attachment. This increases the biomass concentration without the need for increasing the mixed liquor suspended solids (MLSS) concentration, reducing the cost of operating the return activated sludge (RAS) line.

IFAS is often confused with MBBR. Although similar in configuration, IFAS usually includes both fixed film and suspended biomass, So the RAS line is functional, but at a lower rate. Whereas in an MBBR, the process is strictly fixed film with biomass attached to the surface of the media. The media used both in an IFAS and MBBR are not consumed or recycled, hence additional screens are required to prevent the media from washing out of the desired basins. Additionally, pretreatment screens might be needed to prevent undesired waste from clogging the media.

The media used in these systems come in all shapes and sizes, mostly made of plastic. The design of the media is such that maximum surface area is available for biomass attachment, allows easy transfer of nutrients and oxygen and is relatively simple to extrude/manufacture. The smaller the media, the finer the barrier screens, the larger media can make do with the regular coarse screen. The screens have a partial impact on the plant hydraulics, resulting in increased overall headloss. Also, smaller media is more prone to clogging and restrictive to transfer of nutrients and oxygen, hence operates at a lower efficiency compared to its large media counterpart.

While upgrading an existing AS plant into an IFAS or a MBBR system, it is common to alter the air diffuser system. While most AS plants use full floor fine bubble diffusers, most IFAS and MBBR systems require either partial floor fine diffusers or full floor coarse bubble diffusers.

The advantages of switching an AS plant into an IFAS or MBBR system are:

*The ability to increase plant capacity without increasing basin volume, most manufacturers claim a 50 percent increase in throughput

*Able to fully nitrify in systems previously partly nitrifying or not nitrifying at all

*Also, it is know that fixed film systems are more adaptive to changing influent conditions

Maintenance is relatively minimal as these processes do not require backwashing or scouring of the media, excess biomass simply passes through the screen to the secondary clarifiers.

While there are numerous IFAS or MBBR options to choose from, it is imperative to take this into consideration the following factors before selecting a system.

*Headloss: Increase due to addition of screens

*New aeration system: If a particular iFAS or MBBR system requires an aeration system different from the existing type

*Cost: the lifecycle cost must be worked out aside from capital and operating expense

Where situation permits, sustainability and ecological impacts of these processes should be considered prior to selection. Also, a thorough feasibility study should be performed prior to selecting the best treatment option for a given plant. This might include, but is not limited to, an onsite pilot study to evaluate technology feasibility, a lifecycle cost analysis and impact assessment for each alternative.

January being the National Radon Action Month, its time to refresh the awareness related to the issues of Radon in the environment. Here is a brief review of Radon, indoor Radon concentrations, its impact on human health, and mitigation measures.

Smoking, Radon, and passive (secondhand) smoke are the leading causes of lung cancer. Association of smoking with lung cancer and deaths are widely known facts but Radon as a leading cause of lung cancer in non-smokers and second only to smoking in smokers is a less known fact. Because exposure to high levels of Radon is preventable, there is a pressing need to create awareness in public about health effects of Radon, test homes and schools for Radon concentrations and take necessary actions.

Radon (Rn) is a radioactive inert gas, produced as a decay product of Uranium. Radon has a half-life of 4 days. Uranium occurs naturally in the earth’s crust and continuously undergoes radioactive decay releasing Radon along the way. Being a gas, Radon eventually finds its way up through the soil surface and into the atmosphere. The average background Radon concentration outdoors is 0.4 Pico curies per liter (pCi/l) of air. Radon enters the buildings primarily through the floor (foundation cracks and openings) and builds up in concentration indoors depending on the design of the house, local geology, soil conditions, and weather.

Radon, as such, is not harmful to humans. However, being a radioactive gas emits alpha particles, further decays to Polonium, and eventually to stable Lead. Lead gets deposited onto the indoor air and dust particles, which then eventually enter the lungs when inhaled. Alpha radiation causes damage to sensitive lung tissues. Rather than Radon itself, its decay products further decay quickly producing radionuclides that damage lung tissue.

The U.S Environmental Protection Agency (EPA) indoor air quality standards require the Radon concentrations not to exceed 4 pCi/L of air. To learn more about Radon, please visit the EPA website http://www.epa.gov/Radon

Radon easily dissolves in water and is found in drinking water where groundwater is the primary drinking water source. Because of its gaseous nature, dissolved Radon easily escapes into air when water is agitated or stirred. Radon in water is not a major health concern because alpha particles emitted by Radon and its decay products in water readily lose their energy and are taken up by other compounds in water.

The first and foremost step, after knowing about Radon and its associated hazards, is to test homes and other sensitive indoor buildings to Radon levels. EPA and the Surgeon General recommend testing for Radon in all rooms below the third floor. EPA recommends testing for Radon in schools. Radon testing can be done using low-cost “do-it-yourself” Radon test kits or through certified Radon professionals. If found in concentrations exceeding 4 pCi/L, the next step will be to take measures to reduce it. The typical mitigation system, which is relatively inexpensive, usually has a pipe through the basement floor to the outside of the building. The pipe may also be installed outside the building. A small exhaust fan in the pipe enhances the suction to expel Radon from the floor underground to outside air.

Taking action regarding indoor Radon is purely on a voluntary basis. Just knowing that Radon is carcinogenic, occurs naturally and is the cause of an estimated 21,000 deaths {according to EPA’s 2003 Assessment of Risks from Radon in Homes (EPA 402-R-03-003, http://www.epa.gov/Radon/risk_assessment.html)}, should encourage people to take actions to protect from its dangers. The low cost of treatment makes it a very worthwhile investment.

A detailed document about protection from Radon can be found at http://www.epa.gov/Radon/pubs/citguide.html

Nitrogen and phosphorus are the nutrients of interest in water discharging into sensitive water bodies such as the Chesapeake Bay. It is estimated that nitrogen in excess of 400 million pounds is introduced each year into the Chesapeake Bay alone, mainly from agricultural runoff and wastewater plants from 7 northeastern states. Major contributors of nutrients to receiving water bodies are non-point sources; agriculture alone accounts for over 60 percent of the bays pollutants. Poor watershed management, complex farm economics and lack of models to identify individual non-point contributors have passed the burden of clean up to known point sources such as wastewater treatment plants.

Millions of dollars are invested each year to upgrade wastewater plants. Assessing treatment feasibility and economics of mitigating the nutrient crisis warrants an evaluation of available technologies and their limitations.

Some wastewater treatment plants (WWTP) discharging into the sensitive receiving bodies are required to reduce nitrogen pollutants loads in excess of 60 percent. Only a handful of technologies claim to guarantee the required discharge limits, which in some cases are as low as 3 mg/L total nitrogen. A brief summary of available technologies is presented below, while the list of available treatment options are not limited to the list below, selections were made based on popular acceptance of such technologies.

*AS: Activated Sludge (AS) process is commonly used by most WWTPs for biological treatment. This process usually involves large aeration basins (anoxic, but well mixed in case of denitrification), with highly active biomass in suspension, consuming organics and nutrients indigenous to wastewater. Although technologies like integrate fixed film/activated sludge (IFAS) and moving bed biological reactor (MBBR) are gaining popularity, we will limit this summary to the more simpler AS process. Simpler AS plants only help reduce biochemical oxygen demand (BOD), but can be adopted to reduce ammonia and nitrates. This process is limited by the rate of operation, the plants are usually large in size and require numerous stages of treatment to get to the 3 mg/L limit if applied.

*BAF: Biological Aerated (or Anoxic) Filter (BAF) combines filtration with biological carbon reduction, nitrification or denitrification. BAF usually includes a reactor filled with a filter media. The media is either in suspension or supported by a gravel layer at the foot of the filter. The dual purpose of this media is to support highly active biomass that is attached to it and to filter suspended solids. Carbon reduction and ammonia conversion occurs in aerobic mode and sometime achieved in a single reactor while nitrate conversion occurs in anoxic mode. BAF is operated either in upflow or downflow configuration depending on design specified by manufacturer. Popular among the BAFs are downflow sand filters with attached biomass systems treating nitrate rich wastewater. This process is limited by the rate of operation, large footprint and requires a process called bumping to release trapped gases in the media. Alternatively, BAFs designed in the upflow manner eliminate these limitations and are increasingly accepted.

*MBR: Membrane Biological Reactors (MBR) are of growing interest and are fast becoming the treatment option for small wastewater plants. MBRs includes a semi-permeable membrane barrier system either submerged or in conjunction with an activated sludge process. This technology guarantees removal of all suspended and some dissolved pollutants. The limitation of MBR systems is directly proportional to nutrient reduction efficiency of the activated sludge process. The cost of building and operating a MBR is usually higher than activated sludge or a BAF process.

While there is no ‘one technology-fits-all’ option, the general rule for selecting the best technology for a given plant depends on three key aspects- space, capital and personnel skill.

*For plants with limited land and limited capital: BAF, cost is the deciding factor, personnel training to familiarize with new treatment may be required

*For plants with ample land for expansion and limited capital: AS, cost is the deciding factor

*For plants with limited land and ample capital: MBR (or BAF)

*For plants with ample land and ample capital: All of the above, other considerations may apply

Finally, sustainability and ecological impacts of these processes should be considered prior to selection. For example, simpler technologies like AS have relatively low impact as compared to the other options. Another consideration should be the amount of synthesis the components of these processes undergo prior to use, for example choosing a BAF with sand or clay over polystyrene, or membrane technologies that have limited lifetime and may include materials that from non-renewable sources like petroleum. Also, a thorough feasibility study should be performed prior to selecting the best treatment option for a given plant. This might include, but is not limited to, an onsite pilot study to evaluate technology feasibility, a lifecycle cost analysis and impact assessment for each alternative.

The Energy Policy Act of 2005 has a strategy for energy conservation and clean fuel/clean air technology development and implementation. Below are some areas that needs more emphasis regarding long-term sustainability of energy efficient technologies and practices and the way they effect global environment.

*About 60% of the green house gases (CO2, Methane, Nitrogen oxides, and CFCs) are CO2. Energy related activities account for about 80% of the CO2 put into the atmosphere every year (Hinrichs and Kleinbach, 2002). The U.S., being the top oil consuming country, which uses a mammoth 20 million barrels of oil each day, needs major oil savings provisions in the transportation sector including passenger fuel economic, bio-fueled, hydrogen, electric vehicles, etc., and in the energy intensive industrial sector.

*Appliance credits are for the products produced in the U.S. This doesn’t help in any way for the imported goods. This is a major blow for the ‘less-energy clean environment’ programs that intent to address adverse global environment/global climate change/global warming because the US market is dominated by foreign goods. Countries like china and India have vast reserves of coal which they are certainly going to burn to fuel economic growth. Annual per capita emissions of CO2 is 2.8 metric tons by China, and 1.1 by India compared to US (21), Germany (11), and Japan (9.3). The claim that the Asia-Pacific Partnership on Clean Development program is authorized by the energy bill seems insignificant. Environmental Impact Factor (I) is directly proportional to population (P), Consumption©, and Technology & Fuel (F) i.e. I = P*C*TF.

*Incentives for energy efficient technology and practices, and waste utilization (example: Methane) in agriculture (animal feeding operations, fertilizer/manure applications, machinery) and landfills. Methane, mostly from rice fields, cattle, and landfills, has a Global Warming Potential (molecule’s ability to absorb thermal radiation relative to that of CO2) of 21.

*Promote mass transportation, encourage renewable energy and other advanced energy sources including solar, wind, geothermal, fuel-cell, bio-fuels.

*More emphasis on public awareness and education programs to promote energy efficient lifestyles that would eventually save valuable dollars and even-more valuable ‘environment’.

*Provide ready technical assistance, authorize more funding for R&D in cutting-edge technology, and promotional programs for energy efficient technology and practices.

*Needs more incentives for an extended period of time and mandatory adoption of energy efficient technology.

*R&D and other programs to encourage carbon sequestration.

Reference : Hinrichs, R. A and M. Kleinbach. 2002. Energy: Its Use and the Environment, Third Edition, Thomson Learning, Inc.

The use of geographical information systems (GIS) in enhancing the predictive capabilities of environmental software models as well as being a decision support tool is well known and documented. Spatially distributed parameter models may be coupled with GIS to enable visual assessments and such integration benefits decision makers. GIS allows the user to analyse and display spatially referenced data, and provides an interactive environment to construct models and to make models easier to use (Goodchild et al., 1996) and aid in modeling complex resource and environmental systems (Rolando et al., 1995). The strategy for integrating environmental models with GIS can range from loose coupling through the exchange of data files to tight coupling where model algorithms are embedded within the GIS using programming languages (Maidment, 1993; Tim, 1996) or GIS functionality is built within models (Karimi, 1995). Literature reports that a tight coupling between the model engine and GIS, depicted in Figure 1, results in a powerful up-to-date tool that facilitates better data storage, manipulation and analysis than conventional methods (Yoon, 1998).

However, some researchers prefer a loose coupling in which GIS would act as a data analyzer, pre and post model run, as shown in Figure 2, as it allows for flexibility in modelling and increased options in the use of GIS. In a loose coupling, data generated from the environmental model is analyzed and reformatted for display by the GIS (Crawford et al., 1998). In order to efficiently couple models with GIS, the desired aims of the using the model must be known prior to the integration, such as required prediction scenarios. Understanding how GIS can enhance modeling is a necessary step towards a meaningful integration.

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