ABSTRACT
This paper presents the results for thermo-tolerant coliform (TTC) decay rates (K(b)) in a full scale WSP system located in Natal-RN, northeast Brazil. The series comprises a primary facultative pond (2 m deep), followed by two maturation ponds (1.5 m deep) giving a total area of 11 ha. The influent sewage and the pond effluents were monitored weekly during a seven month period. The results showed that the K(b) values predicted by the Marais equation assuming a hydraulic regime of complete mixing overestimated TTC die-off rates. The K(b) value adopted in the project design was 6.20 d(-1) but the mean value found for the WSP system during the monitoring programme was only 0.85 d(-1). This value is low compared to the values cited in the literature for shallow ponds (<1.25 m deep) but similar to values for deeper ponds. The sub optimal TTC removal rate in this WSP system may be caused by the adoption of too high a K(b) value at the design stage and the negative influence of high wind conditions on the mixing regime in the water columns of the ponds. Thus values for K(b) adopted at the design stage of WSP systems should be coherent with the hydraulic flow model, the type of pond, pond depth, and with the surface organic loading.
Subject(s)
Enterobacteriaceae , Hot Temperature , Waste Disposal, Fluid/methods , Water Microbiology , Brazil , SewageABSTRACT
Os autores apresentam um raro caso de enfisema retroperitoneal, mediastinal e cervical desenvolvido a partir de uma perfuracao traumatica do reto subperitoneal. O mecanismo e modo de difusao dos gases colonicos para o mediastino sao discutidos. O diagnostico foi feito pelo achado radiologico de pneumoretroperitoneo, pneumomediastino e enfisema cervical. A evolucao foi favoravel sob tratamento cirurgico
