BIORREATOR A MEMBRANA DE LEITO MÓVEL TRATANDO EFLUENTE DE BAIXA CARGA DE INDÚSTRIA DE PAPEL: EFEITOS DA VARIAÇÃO DO TEMPO DE DETENÇÃO HIDRÁULICA NO DESEMPENHO E NA COLMATAÇÃO DAS MEMBRANAS

Abstract

The membrane bioreactor (MBR) technology has been investigated in recent years in the treatment of wastewater from the papermaking industry, due to the fact that it presents excellent performance in removing pollutants. The introduction of support material in this system, becomes a modern treatment alternative, since the presence of biofilms can provide an additional shock loar capacity, as well as contributing to the degradation of potentially toxic and recalcitrant compounds such as lignin derivatives. Thus, the present work aimed to evaluate the performance of a sequencing batch moving bed membrane bioreactor, (SB-MBMBR) in the treatment of low organic load effluent from a tissue paper production plant using recycled fibers. In this case, the effect of the variation in the hydraulic detention time (TDH) of 10,9 and 21,9 h (called strategies 1 and 2) was evaluated on the performance regarding the removal of pollutants present in these effluents as soluble COD (CODs), total phenols, true color, ammoniacal nitrogen (N-ammoniacal) and aromatic (UV254) and ligninic (UV280) compounds and, especially in variables related to the mixed liquor fouling potential: transmembrane pressure (TMP), membrane fouling index (MFI), sludge volume index (SVIdiluted) and extracellular polymeric substances (SMP and EPS). It was also evaluated if the variation of the HRT influences the concentration of volatile suspended solids and volatile attached soilds (VSS and VAS) and, if the presence of the biofilm contributes to the reactor performance. Under the conditions tested, the increase in TDH contributed to improve the performance of the reactor in the removal of CODs and compounds derived from lignin (UV254 and UV280) (with the exception of N-ammoniacal). Total phenols and true color were not influenced by HRT. The concentrations of VSS and VAS decreased with the increase in HRT, and the presence of biofilm had little contribution to the reactor performance. Regarding the mixed liquor fouling potential, the 21,9 h HRT decreased the variation of TMP and the concentrations of MFI, EPS and SMP, both in the form of polysaccharides. The variables SMP, UV254, UV280 and total phenols were directly correlated with the increase in TMP and, the CODs indirectly influenced the membrane fouling rate. Finally, it was concluded that both operational strategies contributed satisfactorily to the removal of contaminants, however, when taking into account the membrane fouling rate, strategy 2 showed the best results.