Proposta de tratamento de águas residuárias de indústria de defensivos agrícolas visando ao reúso : tecnologia MBBR e processos físico-químico

Abstract

An industrial complex wastewater containing sanitary wastewater (91.5%), pretreated wastewater from pesticide production (3.8%) and hazardous waste landfill leachate (4.7%) was treated in a moving bed biofilm reactor (MBBR) operated at a hydraulic retention time (HRT) of 6 h. During 90 days of operation, the reactor was stable regarding the removal of organic matter (64 to 89% in terms of COD) and ammonium nitrogen (89 to 98%). Even with fluctuations in the feed wastewater COD (230– 721 mg/L), wastewater after biological treatment always presented COD below 100 mg/L. Nitrification took place without inhibition throughout the operation, as shown by the lower ammonium nitrogen concentration (~1.3 mgN-NH4 + /L) and higher nitrate concentration (~20 mgN-NO3 ⁻ /L) in treated wastewater. In order to assess the possibility of industrial reuse, the MBBR effluent was added to raw water fed to the water treatment plant in a 1:9 ratio. Results indicate that a microfiltration or ultrafiltration unit must be coupled to the conventional reverse osmosis pre-treatment (coagulation/flocculation, sedimentation, rapid filtration and cartridge filter) in order to produce water with better quality concerning SDI15, turbidity and color, and thus allow for reclamation of the industrial complex wastewater.