Effects of volumetric load in an anaerobic sequencing batch biofilm treating industrial saline wastewater.

Mustard tuber wastewater is of high salinity ([Cl(-1)]=18∼23 g L(-1)), high organic content (chemical oxygen demand, COD=4000±100 L(-1)) and biodegradability (BOD5/COD≈0.5). The anaerobic sequencing batch biofilm reactor (ASBBR) pre-treatment, an important step to meet national discharge standard, was applied to reduce much of the organics in mustard tuber wastewater. The experiment for the effect of the volumetric load on ASBBR treating mustard tuber wastewater was conducted at different hydraulic retention times (HRTs) and volumetric exchange ratios (λ). The ASBBR operating at 50% biomass density, 30 °C, influent COD concentration of 4000±100 mg L(-1) and pH value of 7.0±0.2, the effluent COD concentration increased from 0.22 to 4 kgCOD m(-3) d(-1) when the volumetric load increased from 100 to 1520 mg L(-1). The effluent COD concentration differed when adopted different HRT and λ under the same volumetric load. And given certain influent levels, a higher performance of ASBBR could be achieved at a lower value of HRT and λ. The optimal operational load could be determined by limiting the COD concentration under different discharge conditions, based on the results obtained in experiments.

Remoção de sulfato de águas residuárias industriais em reator anaeróbio de leito fixo operado em bateladas sequenciais / Sulfate removal from industrial wastewaters in fixed film anaerobic sequential batch reactor

Avaliou-se o potencial de uso reator anaeróbio operado em bateladas seqüenciais com biomassa imobilizada (ASBBR), em escala piloto, no tratamento de água residuária industrial contendo elevadas concentrações de sulfato. O ASBBR, com volume total de 1.2 m³, foi preenchido com carvão mineral como meio suporte para imobilização da biomassa (leito fixo). Foram aplicadas cargas de 0,15; 0,30; 0,65; 1,30 e 1,90 kg SO4-2/ciclo (ou batelada) com duração de 48 h, correspondendo, respectivamente, às concentrações de sulfato no afluente de 0,25; 0,50; 1,0; 2,0 e 3,0 gSO4-2.l-1. Utilizou-se etanol como doador de elétrons para a redução do sulfato. O reator foi operado à temperatura ambiente (29±8ºC), tendo sido obtidas eficiências médias na redução de sulfato entre 88 e 92 por cento em 92 ciclos (275 dias). Os resultados obtidos permitem concluir que o uso de reatores ASBBR constitui-se em alternativa eficiente para a remoção de sulfatos de águas residuárias com características semelhantes às utilizadas neste trabalho.

The potential use of an anaerobic sequencing batch biofilm reactor (ASBBR) in pilot-scale for the treatment of a sulfate-rich industrial wastewater was evaluated. The pilot 1.2 m³ ASBBR reactor was filled with mineral coal for biomass immobilization (fixed film). The sulfate loading rates applied were 0.15; 0.30; 0.65; 1.30 and 1.90 kg SO4-2/cycle (or batch). Each cycle lasted 48 h. The influent concentrations were, respectively, 0.25; 0.50; 1.0; 2.0 and 3.0 gSO4-2.l-1. Ethanol was used as electron donor for sulfate reduction. The reactor operated at ambient temperature (29±8ºC), and the mean efficiencies of sulfate removal were in the range 88 to 92 percent in the 92 run cycles. The total operating period comprised 275 days. Based on the results obtained in this research, it could be concluded that the ASBBR can be an efficient alternative for the removal of sulfate from other industrial wastewaters with similar characteristics.