Caracterização e tratabilidade biológica dos efluentes líquidos gerados em cabines de pintura de uma indústria moveleira

O objetivo deste trabalho foi caracterizar os efluentes gerados em cabines de pintura de uma indústria moveleira e avaliar a eficiência de sistemas biológicos (anaeróbio e aeróbio) para o seu tratamento. O efluente industrial apresentou elevado teor de matéria orgânica (DQO total de 634 a 2.790 mg.L-1; DBO5 total de 360 a 972 mg.L-1) e baixos teores de macronutrientes (NTK de 1,9 mg.L-1 e Ptotal de 0,5 mg.L-) e metais tóxicos. Os ensaios de tratabilidade em reator UASB (~25ºC e tempo de detenção hidráulica - TDH = 10 horas), indicaram uma eficiência máxima de remoção de matéria orgânica de 90% na composição volumétrica 70:30 (efluente industrial:esgoto sanitário). A alimentação do reator UASB só com efluente industrial resultou em acúmulo de ácidos graxos voláteis e inibição microbiana, mas o uso de pós-tratamento aeróbio (TDH = 96h) garantiu elevada eficiência global (~88%) de remoção de matéria orgânica.The main objective of this work was to characterize the wastewater from the dying hood of a woven furniture industry, and to assess the efficiency of biological processes (anaerobic and aerobic) for its treatment. The physical-chemical characterization of the industrial wastewater showed a high organic matter content (total COD from 634 to 2,790 mg.L-1; total BOD5 from 360 to 972 mg.L-1), low content of macronutrients (NTK of 1.9 mg.L-1 and P of 0.5 mg.L-1) and toxic metals. The anaerobic degradation tests in a bench-scale UASB reactor (25ºC and hydraulic retention time - HRT = 10 hours) showed that a maximum removal efficiency of 90% was obtained when the reactor was fed with 30% raw sewage and 70% industrial wastewater. The feeding of UASB reactor with only industrial wastewater resulted in volatile fatty acids accumulation and microbial inhibition; however, the use of aerobic post-treatment (HRT = 96 hours) granted a high (~88%) organic matter removal efficiency

Partida de reator anaeróbio compartimentado em série com um reator anaeróbio de manta de lodo, utilizando parâmetros de sedimentabilidade para formação da biomassa

RESUMO Este estudo objetivou avaliar a formação da biomassa de boa qualidade tanto no reator anaeróbio compartimentado (RAC) quanto no reator anaeróbio de manta de lodo (UASB), aplicando parâmetros adequados à sedimentação dos sólidos sedimentáveis (SS) presentes na água residuária de suinocultura (ARS). O RAC e o UASB operaram em série com os tempos de detenção hidráulica (TDHs) de 15 e 9h, respectivamente, correspondendo a cargas orgânicas volumétricas (COVs) médias de 53,8 e 36,2 kg.m³.d¹ em termos de DQOT, respectivamente. As eficiências médias de remoção de DBO520°C, durante o processo de partida e formação da biomassa, foram: 68% para RAC e 55% para UASB, e em termos de DQO: 78% para RAC e 70% para UASB, respectivamente. Os autores concluíram que é possível, mediante os parâmetros de sedimentação adotados, formar uma biomassa peletizada, mesmo operando o sistema com altas cargas orgânicas

Organic material solubilization of domestic primary sludge in anaerobic digestion at controlled pH

The role of the pH in the anaerobic digestion of domestic primary sludge at mesophilic temperature was evaluated. Since solubilization of organic materials is seriously affected by pH, much research has been performed for the evaluation of significant pH influence on the production of soluble organic carbon in the acid phase. In this study, the performance of continuously stirred anaerobic reactors for the production of soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFAs) in domestic primary sludge was investigated. In the first anaerobic reactor, the pH was not controlled (pH-uncontrolled) whereas the pH was fixed at 6.5 (pH-controlled) in the second reactor. Two sets were performed. Results of both sets indicated that, VSS was removed with a corresponding production of VFAs and SCOD in both reactors. However, production of VFAs and SCOD stopped earlier in the pH-controlled reactors. Methanogenic phase started to operate at earlier times whereas hydrolysis and fermentation were still operating in the pH-uncontrolled reactors. The process stability and efficiency of anaerobic digestion of substrates such as domestic primary sludge can be improved by anaerobic digestion elutriated phased treatment (ADEPT) in which the acid elutriation reactor and methanogenic reactor are separated. In this respect, ADEPT was introduced.</jats:p

The role of pH in the organic material solubilization of domestic sludge in anaerobic digestion

The effect of pH on anaerobic solubilization of domestic primary sludge and activated sludge was investigated and compared. Anaerobic solubilization was carried out in continuously stirred anaerobic reactors at mesophilic temperature (35°C) and pH was fixed at 6.5 (pH-controlled). Many researches reported the serious effects of pH on the solubilization of organic materials. Thus, the aim of pH control in the reactors consisting of domestic primary and activated sludges, was the evaluation of retardation in hydrolysis/acidogenesis at low pH values. Since primary and activated sludges have different biodegradation characteristics, results were compared. Results indicated that the destruction of Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS) were better in the pH-controlled reactors. In both sludges, acetic acid was the main Volatile Fatty Acid (VFA) produced. In the pH-controlled reactors, VSS reduction was found to be 72% in about 20 days in the anaerobic digestion of activated sludge, whereas for the same interval VSS reduction could only be achieved by 32% in primary sludge at 35°C. When primary sludge was used as substrate, the pH-uncontrolled and the pH-controlled reactors removed VSS with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). However, production of VFAs and SCOD was ceased after 5 days in the pH-controlled reactor whereas VFAs and SCOD production continued after 5 days in the pH-uncontrolled reactor, which indicated that hydrolysis and fermentation did not complete and continued longer. On the other hand; in either the pH-uncontrolled or the pH-controlled reactor of activated sludge, VSS was not removed with a corresponding production of VFAs and Soluble Chemical Oxygen Demand (SCOD). It was apparent that solubilization was occurring, however this solubilization was not observed as VFA production. When total methane production and total COD (CODtot) removal were estimated using VSS removal in both types of sludges, results indicated that pH control enhanced biogas productions as well as CODtot removals.</jats:p

The Kinetics and Settleability of Activated Sludge Developed Unider Pure Oxygen Conditions

Center for Water and the Environmen