Study On Discrimination And Toxicity Of Toxic Substances To Sludge In Sewage Plant

With the rapid development of the industry, the types and quantities of the waste water havebeen rapidly increased since the beginning of the twenty-first century. These industrialwastewater contains ingredients with a large number of toxic substances, which are verycomplex. Although these industrial wastewater will be done with some special treatmen beforedischarged into water bodies or municipal sewage, there are inevitably always a number of toxicand hazardous substances or, worse, some of the non-performing enterprises will treat industrialwastewater directly without waste-water treatment. These waste water will do harm to thebiological treatment system of the municipal sewage treatment plant. Therefor,we need to knowhow to screen out effluent toxicity and how to handle infected wastewater.Based on the above problems, this test has been studied the detection of biological toxicityand toxicity studies of biological treatment systemssodium hypochlorite, takding sodiumhypochlorite, surfactant and phenol for example.Daphnia magna acute toxicity test method has been stipulated under GB/T13266-91, wherethe organism Daphnia acts as the test magna. The24h acute toxicity of sodium hypochlorite,surfactants, and phenol has been tested. The results show that: the24h-LC50of sodiumhypochlorite, surfactant, phenol Daphnia magna is0.216mg/L,8.590mg/L,41.295mg/Lrespectively.The three substances toxic to Daphnia magna its concentration is a significantpositive correlation.SBR reactor acts as the wastewater treatment system in the laboratory simulation condition(operating parameters: DO from1.0to2.0mg/L, the aeration stage time5h, the reaction pH7.5-8.5). By measuring the activated sludge oxygen uptake rate (OUR) value, the removeal ratesof ammonia, TP, and COD, the toxic effects of sodium hypochlorite, surfactant and phenol on theactivated sludge system have been studied. The results show that:(1) When the concentration ofsodium hypochlorite was0.5mg/L, the value of OUR was32.7mg/(g·h), the removal rates ofAmmonia, TP, COD were95.6%,88.7%,91.2%.The sodium hypochlorite with thisconcentration has no effect on the activated sludge; When the concentration of sodiumhypochlorite was1-3mg/L, the value of OUR decreased with the increasing of the concentration, the removal rates of Ammonia, TP, COD were decreased. The ammonia removalchanges is similar to OUR value, but TP and COD removal rates of change are no law.(2) Whenthe concentration of surfactant was5mg/L, the value of OUR was33.2mg/(g·h), the removalrates of Ammonia, TP, COD were96.5%,85.8%,88.9%, the surfactant with this concentrationhas no effect on the activated sludge;When the concentration of surfactant was10-40mg/L, thevalue of OUR decreased from24.6to9.2mg/(g·h), the removal rates of Ammonia from83.6%to39.5%, TP from73.2%to50.8%, COD from75.3%to44.7%. The descreasement of the dataindecates that the surfactant is strongly activated on sludge inhibition.(3) When the concentrationof phenol was10mg/L, the value of OUR was9.2mg/(g·h), the removal rates of Ammonia, TP,COD are96.5%,85.8%and88.9%.The phenol with this concentration has no effect on theactivated sludge. With the increasement of the phenol concentration, the removal rates ofAmmonia from95.3%to48.6%, TP from88.7%to55.3%, COD from90.2%to48.6%.