OSA WATER WORKS

POLLUTION CONTROL

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Pollution control has been for several decades a vital concern in industrialized societies where discharges of industrial and municipal aqueous and gaseous pollutants have increasingly threatened ecosystems.  While emissions reduction remains exceedingly important to ensure the sustained integrity of wetlands, riverways, estuaries, and reservoirs, and to reduce the degree of climactic change currently being experienced as a result of greenhouse gas emissions, governmental controls and increasing compliance by the industrial sector have resulted in demonstrable improvements in environmental quality of many industrialized societies.  As one of many examples of the environmental improvement, the mouth of the Delaware River (USA) was so contaminated by discharges from Philadelphia and Camden in the early twentieth century that in the nineteen thirties shad quit migrating up its course to spawn.  In the early nineties the shad began returning to spawn in increasing yearly numbers and today comprise a healthy, restored shad population. 

    While industrial societies have been forced to address environmental contamination, developing countries have in many cases yet to institute the regulatory controls necessary to force industry to cut its contaminant emissions, whether they are aqueous or gaseous.  This is due, largely, to economic competitiveness and the struggle to produce goods that can compete globally with the products of established manufacturing firms in industrialized societies.  This lack of governmental will has produced a curiously destructive tendency among some major industries in today's globalizing business model.  Not only can manufacturers find a labor force in developing countries willing to work for vastly lower wages than their counterparts in the developed world, these same companies can enjoy a lax environmental regulatory system that requires a smaller investment in pollution control, both of which increase the profitability of goods.

    Add to this equation the fact that many developing countries have no centralized plants for municipal sewage treatment and others have substandard sewage treatment technologies in place, and a recipe for environmental disaster is in the crafting.  To complicate matters more, the global population explosion is not coming from industrialized societies but from developing societies, particularly in the tropics, that part of the world located between the latitudes of 30 degrees north and 30 degrees south of the equator.

    Responsible waste management is, in the absence of governmental control, a personal responsibility of all people in the stewardship of our planet.  Whether at the single-dwelling residence stage or at the level of a transnational chemical company producing pesticides, proper waste management is essential for the preservation of existing pristine environmental ecosystems and the restoration of ecosystems that have already been damaged by past excesses.

    Osa Water Works provides design and installation of simple septic systems for homes and aerated septic systems for lodges.  Though we rarely get the chance to work on such projects, we welcome inquiries about constructed wetlands, municipal waste water treatment, landfill design, waste minimization and resource recovery, and recycling.  Waste management recommendations, particularly in underdeveloped societies, must always include a balance between three basic factors:  1)  the best management practices for the problem being corrected;  2)  appropriate technology for the region encompassing the problem;  and 3) economic viability of the alternatives under consideration.

An overview of waste management alternatives that OWW includes in its tool-kit for developing-world pollution control are listed below.  OWW does not offer consultation, services, or products for gaseous emissions.

Remote Domestic and Small Community Waste Management

1.  Septic Systems.  Where municipal sewerage is unavailable, septic systems are the most widely used residential waste management alternative.  They consist of a buried single- or multi-chambered concrete bunker where solid waste settles and undergoes anaerobic decomposition.  Liquid waste is conveyed from the top of the septic tank to a leach field that discharges the waste into soil, where it is degraded naturally by aerobic bacteria.  The efficiency of degradation is affected by a multitude of environmental and usage factors, including:  loading rate, tank size, leach field size and configuration, climate, and depth to ground water, among others.  For homes depending on wells for potable water supply, the location of septic drain fields must always be down-gradient from wells and separated by an adequate distance to ensure there is no bacterial contamination of the well water.  The traditional septic system shown below is not always adaptable.  Where ground water levels are very high, there is insufficient soil for aerobic bacteria to degrade waste.  A variety of alternative design have been employed to overcome this problem, including mounded septic systems.

Typical septic system design.

2.  Aerated Septic Systems.  For installations in which the loading rate is greater than the capacity of a typical septic system to digest, aeration may be introduced, which provide bacteria with supplementary electron receptors and enable them to sustain large healthy colonies, which dramatically increase the rate of biodegradation.  Aerated septic systems are typically appropriate for lodges, research stations, and very large residences with many occupants.

                                        Three example designs of aerated septic systems.

3.  Constructed wetlands.  Constructed wetlands represent an attractive waste-water disposal alternative in low-relief areas with high ground water tables, typically in swampy or marshy ecosystems.  The theoretical basis for constructed wetlands is that a variety of plants have large waste-assimilative capacities and can be deployed in configurations that enable bacterial colonies to provide additional biodegradation.  Although constructed wetlands must be carefully designed to ensure the waste-assimilative capacity is not exceeded by loading rate, it is a robust alternative to septic systems.  Disney World, in Orlando, Florida, for example, depends on a constructive wetland for the management of the sewage generated in its facility.

Constructed wetlands for the management of waste for a single-family residence.

4.  Conventional Waste Water Treatment  Municipal waste water treatment typically involves some variation of the following unit operations and processes in the order given:  1)  Comminution;  2) Primary Settling;  3) Secondary aerobic treatment;  4) Secondary Settling;  5) Sludge digestion (either aerobic or anaerobic); 6) Sludge dewatering and disposal;  7) Effluent chlorination;  8)  Effluent dechlorination;  9)  Effluent discharge to a natural waterway.  Variations on this flow train vary according to the regulatory environment of the municipality in question, and in developing countries, sewage treatment plants are nearly always much more basic than what has been described above and represent severe environmental stress to the waterways that receive the poorly treated effluent.  Conventional waste water treatment carries substantial capital and operating costs and represents a viable alternative for waste management only on the municipal scale.

Conventional wastewater treatment plant

5.  Recycling Programs.  Recycling serves two environmentally helpful purposes:  1)  it reduces the demand for raw materials by re-using such materials that can be recycled, including paper, plastics, glass, and metals; and 2) it reduces the loading rate of sanitary landfills.  While municipal recycling programs exist in a variety of industrialized societies, the same cannot be said for undeveloped and developing societies, where an infrastructure for processing recyclable wastes is less likely to be present.  Transportation of segregated recyclables to a facility that can re-process the wastes is commonly an economic hurdle to the institution of recycling programs.  At a rural residential level, recycling processes that can reduce waste include composting of organic wastes for use in gardening.  In the absence of a societal infrastructure for collecting and transporting recyclable glass, metal, and plastics, rural dwellers are often faced with having to burn plastics and paper and bury what cannot be burned.

6.  Landfills.  There's a big difference between a "dump" and a "sanitary landfill," and in a shrinking world, the management of human refuse has become an area of intense environmental concern owing to the contamination of ground water by landfill leachate.  Due to the unfortunately wide-spread clandestine dumping of toxic industrial chemicals in decades past, many sites around the world have egregiously contaminated aquifers with a wide variety of organic chemicals, which in turn have migrated according to geological constraints, rendering this subsurface water unuseable for decades to come.  Even with aggressive remediation, such sites will remain contaminated for decades if not centuries.  Effective landfill design includes the use of liners and impermeable earth materials to limit the ability of leachate from migrating offsite.  Leachate collection and treatment systems may be factored into landfill design to ensure that this source of contamination is effectively managed.  Finally, landfill management is essential to ensure that inappropriate industrial waste is disallowed.

Industrial Waste Management  

    In the wake of increasingly stringent regulatory controls on industrial emissions and industrial waste disposal practices, industry in developed societies has been forced to completely re-think models of manufacturing to reduce both emissions and waste and to institute costly waste treatment operations that do not "add value" to the product being manufactured, apart from the kudos of being able to proclaim their goods or products as "environmentally friendly" and ostensibly introduce this label into marketing and public relations benefits.  In undeveloped countries, environmental regulations are either lax or unenforced.  If industry is not required by government to utilize best available waste management practices, in most cases, industry will not implement such practices and will knowingly sacrifice the environment for profit.  In today's globalization drive, hopefully the environment will not be excluded from the bargaining table and that planetary stewardship will not fall victim to planetary exploitation.  This remains to be seen.  OWW offers a variety of services and waste treatment designs for industrial facilities seeking to control emissions and waste.  These are summarized below.

1.  Waste Minimization.  The first step of any industry seeking to control its waste is to review all existing process to determine how waste generation can be reduced.  This process is not only industry-specific, but actually facility-specific and may involve any number of changes to achieve this goal, including but not restricted to the following:  1)  substitution of chemicals or raw materials;  2)  modification of equipment and machinery for improved efficiency;  3)  Reuse and recycling;  and 4)  Development of alternate use for some wastes

2.  Resource Recovery.  Many wastes contain potentially valuable chemicals that can either be recovered from the waste stream and re-used within the same industrial process or sold to other industries or end-users that have a use for such materials.  Examples of resource recovery include fuel-blenders that collect discarded oils and greases and sell these materials as fuels for cement kilns, incineration facilities, etc.

3.  Biochemical and Chemical Oxygen Demand control.  Waste with high non-toxic organic content cannot be discharged to the environment owing to the fact that its biodegradation results in oxygen depletion and corresponding fish kills.  A variety of waste treatment alternatives are available for removal of BOD and COD levels.  Variations of conentional waste water treatment methods may be effective for BOD, and chemical oxidation and advanced oxidations may be effective in COD control.  The election of the best treatment alternative necessarily requires a comprehensive understanding of the waste profile, the waste generation rate, the variability of the waste generation rate, and the destiny of the treated effluent.  If, for example, the waste is to be discharged to a waste water treatment plant, then a smaller degree of treatment is required than if the treated effluent is to be discharged directly to a waterway.

4.  Synthetic Organic Compound control.  Toxic organic compounds cannot be treated by conventional wastewater treatment operations because the chemicals are toxic to the bacteria used in such processes.  Depending on the waste profile, SOC contaminants can be concentrated through a variety of physico-chemical processes, either for resource recovery, or for aggressive treatment of concentrated waste.  Advanced oxidation using either hydrogen peroxide, ozone, or both and either chemical or electromagnetic catalysis is commonly the most effective unit operation for degrading SOCs to constituent water, carbon dioxide, and mineral salts, which can in turn be discharged to the environment without any adverse consequences.

5.  Oils and Greases Control.  Oil/Water separation is a relatively simple unit operation used for recovery of a waste with BTU value that can be used as a fuel.  Removal of oils and greases from a waste stream enables relatively easy management of the product water.

6.  Metals Control.  For industrial processes that generate waste streams high in dissolved metals, precipitation and disposal of the precipitate as non-hazardous solid waste is commonly the most viable alternative.  Anodic recovery of reusable metals is an alternative with some waste streams.

7.  Cyanide Control.  Alkaline advanced oxidation is commonly the preferred technology for the oxidation of the cyanide molecule.

8.  Monitoring and Control Programs.  Monitoring and control programs, normally mandated in societies where regulatory bodies have teeth, are advantageous for ensuring that all waste-management processes and operations are operating at the required efficiency.  Periodic plant-scale mass balances of materials and energy are powerful tools for assessing the efficacy of control systems in place.

For a no-obligation assessment of how Osa Water Works may be able to assist your industrial application in its waste-minimization, effluent toxicity reduction, or waste-management efficiency boosting, please provide us with some preliminary information by filling out the relevant sections of the form accessed by clicking here.

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