Formaldehyde biodegradation in an ASBR-SBR system: an effective treatment solution for furniture industry painting booth wastewater

Formaldehyde (HCHO) is a toxic organic compound with carcinogenic properties which is present in the furniture industry painting booth wastewater (PBW) and does not receive adequate treatment in its industrial environment. This effluent treatment commonly occurs by physicochemical processes that do not remove formaldehyde, while advanced treatment methods are costly for industrial scale application. This study assessed a system consisting of an anaerobic sequential batch reactor (ASBR) followed by an aerobic sequential batch reactor (SBR) for the PBW treatment. The system performance was evaluated by the gradual increase of HCHO concentration from 34 ± 5 to 232 ± 10 mg HCHO L−1, and chemical oxygen demand (COD) from 585 ± 8.4 to 3960 ± 100 mg O2 L−1, performed with cycle time of 4 days in ASBR and 2 days in SBR, evaluating the formaldehyde potential toxicity on anaerobic biomass. The ASBR-SBR system removed 99% of COD and HCHO until initial concentration of 180 ± 7 mg HCHO L−1. The HCHO concentration increase to 232 ± 10 mg L−1 reduced the removal efficiency of organic matter to 72% in ASBR due to partial inhibition of microorganisms caused by formaldehyde toxicity. However, under these conditions, the SBR was efficient and removed the remaining organic matter by 98%. The performance of ASBR-SBR showed that this simple system was suitable for the PBW treatment at the evaluated concentrations.