Pós-tratamento de efluentes de filtro anaeróbio precedido de tanque séptico por filtros aeróbios intermitentes de areia

Abstract

The discharging effluents in natura in soil or fresh water resources, directly or indirectly, this results beyond several problems socio environmental, in significant impacts about terrestrial and aquatic life. The absence of treatment in the efluents and your incorrect destination contribute to worsen the environment and the public health. This study aimed to evaluate the application the intermittent aerobic sand filters, as alternative system of post-treatment of effluents preceded of the septic tank and anaerobic filter, aiming the removal of nutrients, organic matter sewage from the science and technology center (STC). The university of Paraiba (UEPB) the system of pos-treatment built in the study is formed intermittent aerobic sand filters composed by three boxes of polyethylene fiber (one that acts like equalization tank and the other two act like aerobic filters.) the two aerobic sand filters (FA1 and FA2) were filed and with gravel and sand in the following proportion: 15 cm of gravel nº 3 in the base, 15 cm of gravel in the superior portion: 15 cm of gravel nº3 in the base, 30 cm of sand in the middle portion immediately above the gravel layer of the base 15 cm of gravel in the superior portion, immediately above the sand layer. The sand was the same, for both FA1 and FA2. The sand filters were fed by down stream. FA1 received effluents of equalization tank during 2 minutes and 45 seconds marked by stop watch, that and corresponds of a flow of 100 L of effluents. FA2 received effluents of the equalization tank during 5 minutes and 30 seconds, corresponding to 200 L of effluents. The average flow a minute was 22.84 l/m. it was verified low removal of organic natter through of total and filtered DQO, in the intermitted aerobic sand filters, with removal efficient bellow the minimum probable by NBR 13969/97 that is 40% may be associated to a short period of time of hydraulic detention in the septic tank due to the lack of periodic cleaning in the septic tank, passing to work like a single passage box. There were great efficiencies in the removal of nutrients, showing a good capacity of nitrification revealed in the nitrate concentration (28 mg/l and 29 mg/l) in FA1 and FA2 respectively and the different rates of application in the two intermitted aerobic sand filters influenced in the process of nitrification.