Estudo comparativo entre reatores de crescimento aderido e disperso pós tanques sépticos tratando esgotos domiciliares

Abstract

The efficiency of removal of the biochemical oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS) and volatile suspended solid (SSV) were studied in two anaerobic reactors which received semi-settled effluent (flow limited around 3.2 times the average flow) of a septic tank, one being adhered growth (R1, with bed of gravel Nº. 4) and the other dispersed growth (R3 without support material for microbial growth). This system was installed in the University Residence at UFPB in João Pessoa-PB. The treated sewage came from two bathrooms that catered to a theoretical population of 4 inhabitants. Eleven samples of the effluent from the septic tank and the effluent from the reactors 1 and 3 were performed in the period between 28/02/2013 and 10/12/2013. The temperature and pH of the reactors were presented in the range 24.5 to 28.1 ° C and 7.3 to 8.1, respectively. Those values are from the anaerobic treatment of household sewage. The BOD5 removal efficiencies (32.8 and 27.1% in R1 and R3, respectively), COD (43.4 and 33.0% in R1 and R3, respectively), SST (56.2 and 48.0% in R1 and R3, respectively) and VSS (54.7 and 46.2% in R1 and R3, respectively) were high. It demonstrates a good applicability of these low-cost housing units which are devoid of collective sewage system in the reduction of pollution load released in water bodies systems. An analysis of variance showed no significant difference of 5% between the average of the corresponding parameters of the two reactors, suggesting that reactor that receives discharges from the attenuation peaks, there is no need of support means, which may represent a reduction in costs involved.