Utilização de um sistema compacto de tratamento de esgoto para remoção simultânea de matéria orgânica e nitrogenada

Abstract

This study aimed to optimize low-cost domestic wastewater treatment, focusing on the removal of organic and nitrogenous matter by using an anaerobic dynamic membrane bioreactor (AnDMBR) followed by an intermittent aerated filter. The external dynamic membrane was developed using a non-woven fabric support material with an average pore size of 28 μm. The process performance was evaluated under three different hydraulic retention times (HRT) — 18, 12, and 8 hours — corresponding to three distinct feeding flows of 779.9, 1169.9, and 1754.8 L.m-²h-1, referred to as assay I, II, and III, respectively. For nitrogen removal, intermittent aerated filters were employed with a fixed inflow rate of 10 L.day-1 regardless of the tests. Statistical analysis revealed no significant differences between the tests for most of the evaluated parameters, except for the total COD of the permeate, which was identified a significant difference at a 5% probability level. The best performances for turbidity and total COD removal were observed in the third test, indicating 8h of HRT as the recommended option, as it allowed high contaminant removal with the highest treated wastewater volume. Turbidity removal efficiencies by the AnDMBR were 90%, 89% and 97% for tests I, II and III, respectively. For total COD, average removals were 83%, 86% and 87%, respectively. The removal efficiencies for total suspended solids and volatile suspended solids were also high, reaching 81% and 82%, 80% and 82%, and 64% and 78% for tests I, II and III, respectively. The highest efficiencies of the aerated filters were achieved in test III, with ammonia removal reaching up to 22%. The low nitrogen removal rates were attributed to the high nitrogen load influent to the system, limited oxygen availability for nitrification, and operational issues that caused system flooding and subsequent displacement of the bacterial community responsible for the nitrogen cycle.