Application of the UASB technology for sewage treatment in a small community at sumare, sao Paulo state

Sumare City does not have sewage treatment, leading to the deterioration 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 communities of low income population are built surrounding the city. That was not foreseen in the city's plan. So, the sanitation problem is constantly aggravated. The city's Water and Wastewater Department (Departamento de A'guas e Esgotos - DAE), worried by this situation tried out a new scheme to overcome this problem. One of those communities (235 houses) was chosen and a proposal was made to its inhabitants, which was accepted, to use an anaerobic digester to treat the sewage, DAE being the financer agent and the inhabitants reimbursing DAE. The UASB technology was made available by means of an agreement between DAE-Sumare and CETESB for technology transfer. DAE was responsible for the management and plant construction. The plant was started-up in May 1992. This is a successful experience in view of the non-existence of finance for the construction of sewage systems. A 67.5 m super(3) UASB reactor was built. The difficulties to establish the real costs for this were extremely high, and lead to cost reduction recommendation. Data collected for performance evaluation, over a period of fourteen months showed a difference compared to the 120 m super(3) UASB reactor experience, 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 removal rates of BOD, COD and TSS are also higher, respectively 80%, 74% and 87%.