Tratamento consorciado de esgoto sanitário com lixiviados de aterros sanitários, lodo de tanques sépticos e efluentes de sanitários químicos por lodos ativados em batelada na ETE Canoas - CORSAN

Abstract

In Brazil, only a small portion of domestic wastewater collected is effectively treated. In most cities, the treatment system used is the septage, which have low efficiency and need for maintenance and periodic removal of sludge, which must be properly disposed. In the cities there is the generation of other types of waste such as sludge from septage, in this case considered an effluent as the water content exceeds 90%, effluent from chemical toilet and sanitary landfill leachate, all generated from urban activities, and require adequate treatment to final disposal. The combined treatment of these external effluents with domestic wastewater has been used as a strategy to reduce the cost of tractability. However, the great variability of composition and concentration of this effluents, make it a difficult treatability mixture, especially on conventional plants. There is still no consensus on the impacts caused by this mixture of effluents on the degradation processes commonly found in DWTPs nor on the safe ratio for the dilution to be adopted in regard to domestic wastewater. DWTP Canoas - CORSAN has an activated sludge system operating in batch, there is the combined treatment of domestic wastewater, sludge from septage, effluent from chemical toilet and sanitary landfill leachate, without a maximum amount stipulated for receipt of these external effluent. This study aimed to characterize the influent mixture and assess the impact of combined treatment on the operating conditions of the DWTP, as well as its performance in the removal of organics and nutrients between January 2009 to August 2010. It was found that the percentage of dilution of external effluent in domestic wastewater varied between 2.1% and 11.3% and that the contribution of this effluents to the total COD load varied between 14% and 74%. The physico-chemical composition of the influent mixture to biological reactor has influence on the composition of the microfauna present in the SBR. The most frequently observed impact by the shock loads entry was the loss of biomass due to flocculation and settling problems, such as bulking. The occurrence of shock loads due to the entry of external effluents promoted an increase in the SVL of 46 mL/g to 287 mL/g, just as there was an increase in the F/M, which increased from 0.42 d-¹ to 0.82 d-¹. Among the metals analyzed for Ca, Fe and K were found in higher percentages in the external effluent samples, corresponding to 15.8%, 10.4% and 10.1% respectively. Were also detected for Cu, Zn, Ti, Cr, in low percentages. In biological sludge were detected 56% Fe, 16% Ca, 10% Si and 8% of S, adsorbed on the flocs, and Zn (4%), Cu (3%), Mn (1.5%) and K (1.2%). The frequent exposure of activated slugde community to shock loads was the main effect to collaborate in the removal efficiencies reduction of TSS, BOD5, COD, TP and N-NH4 +, damaging the quality of the final effluent. The adoption of a unit for receiving and preliminary treatment of external effluents could permit a greater operational control in the receiving and treatment dynamic of external effluents, improving the performance of DWTP.