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8 <br /> Slide #10 <br /> Standards for Effluent Quality <br /> Septic Tank <br /> Effluent <------------ Advanced Pre-Treatment ---------->1 <br /> NSF <br /> ANSI <br /> BOD-5: 350 mg/l CBOD: 15 CBOD: 10 <br /> TSS: 100 mg/1 TSS: 15 TSS: 10 <br /> TKN: 100 mg/I NH3: 10 NH3: 10 <br /> 7 to 15 x better than DSE <br /> Tony Whitaker said success in wastewater treatment is measured by how well <br /> concentrations of certain undesirable characteristics or constituents can be removed, which are <br /> represented on this slide. He said the left represents the least treated effluent standard, and they <br /> are increasingly well treated moving to the right. The concentrations listed are the maximum <br /> allowable concentrations that are generally allowed to flow out of a septic tank and then be directly <br /> dispersed to good, suitable soil for further treatment. However, he said most water coming out of <br /> a septic system is better. <br /> Chair Bedford asked what BOD means. <br /> Tony Whitaker said, Biological Oxygen Demand, is a measure of the load of certain kinds <br /> of bacteria and biological components that consume oxygen as they break down, so that when <br /> the load is sent downstream to oxygenated water, the change to the oxygenation levels in that <br /> water can be observed. <br /> Commissioner Bedford asked him to elaborate on TSS and TKN. <br /> Tony Whitaker said TSS refers to Total Suspended Solids, and TKN is a combination of <br /> different types of nitrogen. He noted that these standards are for the water that's applied to the <br /> soil. He said if the soil is very limited, it could do some treatment, but not great treatment; <br /> advanced pretreatment may be needed, which takes that water to a higher level of treatment <br /> before it is dispersed. He said the water is 7 to 15 times better with advanced pretreatment than <br /> the DSE standard, but it comes at a high cost. <br />