Abstract

SANCHEZ ORTIZ, Iván Andrés  and  MATSUMOTO, Tsunao. BATHYMETRIC SURVEY OF THE NEVES PAULISTA SEWAGE TREATMENT PLANT. Cienc. Ing. Neogranad. [online]. 2014, vol.24, n.2, pp.97-110. ISSN 0124-8170.

Waste stabilization ponds are one of the most suitable natural wastewater treatment systems for reducing the environmental impacts produced by effluents dumping in developing countries. The objectives of this research were to diagnose the sludge accumulation and to evaluate the performance of the sewage treatment plant STP at Neves Paulista city (São Paulo, Brazil). Through a bathymetric study of the anaerobic and facultative lagoons, the profiles and volume accumulation of sludge were determined, different water quality parameters of the plant influent and effluent were measured, and the raw wastewater flow was measured during 24 consecutive hours. Pond bathymetry showed that the accumulated sludge reduced the working volumes of the anaerobic and facultative ponds in 26.4% and 23.7% respectively. Furthermore, the heterogeneous distribution in the lagoons affected their hydraulic performance. The average efficiency removal of BOD was 76.6%, smaller than the minimum efficiency allowed by the Brazilian legislation. The effluent most probable number of fecal coliforms was 6.34x10⁵/100mL, highly exceeding the maximum permitted values for dumping into receiving water bodies. The plant requires the implementation of a pretreatment system, the removal of accumulated sludge in the most critical zones, and the implementation of a post treatment system to guarantee additional BOD and fecal coliforms removal in order to adjust the efficiency to the environmental legislation standards.

Keywords : wastewater; stabilization ponds; bathymetry; sludge accumulation; effluent quality.

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