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As water becomes scarce and as governments apply more stringent regulations for wastewater disposal, an industry has grown up treating the waste liquids and effluents from industries and municipalities.

Conventional aerobic industrial and municipal wastewater treatment (WWT) requires vast amounts of energy, mostly for aeration (oxygen supply) to provide biomass growth. In addition inherently substantial amounts of bio sludge are produced that require expensive treatments and disposal. No one can ignore the energy shortage we are facing today and consequently all our waste handling will be undertaken by improved low energy technologies in the future. Considering that a sizable chunk (greater than 5%) of the energy needs are needed for water treatment, the impact of combining energy minimization with advanced waste water treatment systems could be significant.

The global wastewater treatment industry is worth around $60 billion per annum, with almost an equal split between North America, Europe and Asia amounting to 50% and the rest of the world takes up the remainder.

Industrial influents are discharged from almost all production activities and water is used as solvent (washing) and as ingredient. The run-off is disposed of in the wastewater system, and very high organics loads are commonly found in many industries influents such as large farms and agricultural communities, dairy farms, poultry farms, piggeries, (slurry, manure), aquaculture (fish) farms, meat processing complexes (slaughterhouses, abattoirs), fruit processing, wine (wineries) beer, distilleries, soft drinks, dairy factories, cheese whey, agro industries (coffee, chocolate, sugar cane, sugar refineries, others), pharmaceutical industry, leaching (percolate) from landfills, etc. Many of these industries not only generate high organic loaded wastewater, but also use heat for their production processes. The driving factors for energy minimization considerations are 1) Regulation on disposal of industrial effluents, 2) Price and operational costs, and 3) Foot print -- industrial and agricultural land space can be valuable.

Wastewater treatment is usually divided into chemical, physical, chemical/physical and biological. Biological processes are regarded as expensive and sensitive (up stream events such as toxic substance release, pH changes, etc), require continuous professional attention, occupy large areas, and operate poorly at low temperature conditions. Two major biological treatments are popular; aerobic (including many types of activated sludge) and anaerobic digestion for methane generation. When relating to industries which emit high organic loads, the aerobic treatments are regarded as expensive and are usually employed to reduce the loads before entering the municipal WWTP. On the hand anaerobic (without oxygen input) treatments are even more expensive and regarded as not satisfying from the effluents quality point of view, but are occasionally installed to recover energy. Advanced reactors offer the following integration to simplify design, smaller footprint, lower costs, minimal energy consumption and CO2 emission, low sludge yield and maximize waste to energy conversion efficiency.

• Thermophilic operation of the solids reactor. Anaerobic thermophilic processing (microbial activity in 50-60 degC range) has also been well researched and being commercially used by many applications. The energy efficiency comes from capability to provide higher biogas yields in a single stage reactor system with a smaller footprint for solubles and then optimization of overall process performance in an integrated complete solution approach. The energy needed to heat the reactor can be provided from the system energy production. Mesophilic process requirements (30-40 degC microbial activity) for different category of organics than those processed by thermophilic processing may require operation in intermediate process regime with a wider process window. Other approaches have addressed this problem using a two stage reactor system which has also helped in maintaining better control on process performance and yield.
• Anoxy gas floatation (DAF technology -- dissolved air floatation)
• Anaerobic digestion. This process enables the bacteria to work on the pollutants and treat the water. Previously considered to be too expensive, anaerobic technologies are attracting much attention as methane energy is produced lowering overall energy needs.

The core technology relies on a two reactor design -- parallel and interconnected. There are two reactors, one for dissolved fraction incorporating biomass floatation and advanced bacteria control systems and the other for solids degradation, and there is a symbiosis between the two.

In the general scheme of the process, solids are first separated from the dissolved fraction which is mostly sugars. Because the solids degradation is slower, a separate bioreactor is beneficial so that the overall process is speeded up and the footprint reduced. The waste from the non-soluble reactor is transferred to the dewatering press having stable sludge, and the liquor is recycled into the second solubles reactor. It combines anaerobic, biogas floatation, and fermentation processes. The biosolids are recycled into the solids reactor such that valuable bacteria is not lost and the liquid effluent is disposed in the municipal wastewater treatment plant. Both reactors produce methane which can be put through a generator to make electricity. This energy is used to run the process and the surplus sold back to the grid. In a typical industrial processing application, chemical costs are offset by sludge treatment costs of the standard approach. Since there is a lot of published work and knowledge on anaerobic thermophilic process optimization and scaleup, development cycle is short and faster deployment with revenue generation possible.

The global perspective is changing dramatically, and in particular because of the energy crisis and resource shortages such as fresh water. Adoption of a new approach that will fully address both the energy and environmental issues is required and happening especially in Europe and expected to grow in North America and rest of the world.