From Environmental Management: Wastewater and Groundwater Treatment

Biological wastewater treatment facilities are designed to emulate the purification process that occurs naturally in rivers, lakes and streams. In the simulated environment, conditions are carefully manipulated to spur the degradation of organic contaminants (Chem. Eng., March 1997, p. 74) and stabilize the residual sludge. Whether the treatment process is aerobic or anaerobic is determined by a number of factors, including the composition of the wastewater, the degree of stabilization required for environmental compliance and economic viability.

Because anaerobic digestion is accomplished without oxygen in a closed system, it is economical for pretreatment of high-strength organic sludge. Before the effluent can be discharged, however, followup treatment using an aerobic process is required.

Though it has the drawback of being energy intensive, aerobic processing, the aeration of organic sludges in an open tank, is the primary method for treatment of industrial and municipal wastewater. Aerobic processes are more stable than anaerobic approaches and can be done rather simply, particularly with trickling filters.

Gradually, the commercialization of modular systems that are capable of aerobic and anaerobic digestion will blur the distinctions between the two processes. Systems that boast those capabilities are available now.

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Water softeners remove the hard calcium and magnesium minerals from water.

Topics of Interest

In the absence of molecular oxygen, natural environments depend on the activity of anaerobic microorganisms for the biological degradation of organic substrates. In anaerobic environments where, other...

PROBLEM 4.1 Sludge processing prior to final disposal may be divided into the following unit operations: thickening, stabilization, conditioning, dewatering, and thermal reduction. Identify several...

INTRODUCTION Anaerobic processes are used to treat strong organic wastewaters (biological oxygen demand (BOD) >500 mg l ?1), and for further treatment of primary and secondary sludges from...

AEROBIC BIOLOGICAL TREATMENT Aerobic biological wastewater treatment is the process by which microorganisms use the waste's organic component, in the presence of oxygen, to produce cell growth and...

3.3 Conditioning In many cases, stabilized sludge may be applied directly to land. If it is desired to land apply stabilized sludge in liquid form, sludge from anaerobic digestion, aerobic digestion,...