Wastewater and Effluent Parameters

Chemical Oxygen Demand (COD) is a measurement of the oxygen required to oxidize soluble and particulate organic matter in water. It is an important water quality parameter that provides an index to assess the effects of discharged wastewater on the receiving environment. Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen levels. Thus, it will be harmful to aquatic life. COD can be determined by various method such as closed reflux digestion, by titrimetric method.

Biochemical Oxygen Demand (BOD) is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms when decomposing organic matter in water. Like COD, it is an important water quality parameter because it provides an index to assess the effect discharged wastewater will have on the receiving environment. The higher the BOD value, the greater the amount of organic matter for oxygen consuming bacteria, and thus higher rate of dissolved oxygen consumption. Depletion of DO causes stress on aquatic organisms, making the environment unsuitable for life. BOD is also used extensively for wastewater treatment and is a common gauge to determine the design of the water treatment facility. The most common technique used for the determination of BOD, is the 5-day incubation BOD test and azide modification method.

Ammonia is a colorless, pungent gaseous compound, extremely soluble in water. It is a biologically active compound found in most waters as a normal biological degradation product of nitrogenous organic matter. It also may find its way to ground and surface waters through discharge of industrial process wastes containing ammonia and fertilizers. Ammonia can cause toxicity to aquatic animals and high levels of it can potentially kill aquatic organisms. Various methods can be used for the determination of ammonia in water, but the most common and cheapest among of it is the ammonia-selective electrode method.