APPLICATION OF THE UASB TECHNOLOGY FOR SEWAGE-TREATMENT IN A SMALL COMMUNITY AT SUMARE, SAO-PAULO STATE

Sumare City does not have sewage treatment, lending to the deteriorati on of water resources and public health conditions. There is a sewage treatment plan for the city's urbanized area. However, difficulties of financing delay the plan's implementation. Meanwhile, new small commu nities of low income population are built surrounding the city. That w as not foreseen in the city's plan. So, the sanitation problem is cons tantly aggravated. The city's Water and Wastewater Department (Departa mento de A'guas e Esgotos - DAE), worried by this situation tried out a new scheme to overcome this problem. One of these communities (235 h ouses) was chosen aid a proposal was made to its inhabitants, which wa s accepted, to use an anaerobic digester to treat the sewage, DAE bein g the financer agent and the inhabitants reimbursing DAE. The UASB tec hnology was made available by means of an agreement between DAE-Sumare and CETESB for technology transfer. DAE was responsible for the manag ement and plant construction. The plant was started-up in May 1992. Th is is a successful experience in view of the non-existence of finance for the construction of sewage systems. A 67.5 m(3) UASB reactor was b uilt The difficulties to establish the real costs for this were extrem ely high, mid lead to cost reduction recommendation. Data collected fo r performance evaluation, over a period of fourteen months showed a di fference compared to the 120 m(3) UASB reactor e perience, at CETESB, in Sao Paulo City. The influent and effluent Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD) and Total Suspended Solids (TSS) values, are higher than were experienced at CETESB. The average remova l rates of BOD, COD and TSS are also higher, respectively 80%, 74% and 87%.