Cork boiling wastewater management by anaerobic digestion

• Author(s): Gonçalves, M. R. ; Gil, Luís ; Marques, Isabel Paula
• Date: 2012
• Persistent ID: http://hdl.handle.net/10400.9/1668
• Origin: Repositório do LNEG
• Document Type: Conference object
• Language: English
• Contributor(s): Repositório do LNEG

Description

Cork boiling wastewater (CBW) is an aqueous and complex effluent of the cork industry which is produced during the boiling of the cork planks, one of the key operations in cork processing for cork stoppers production. CBW contains suspended and dissolved solids and organic materials such as phenolic compounds and is characterized by a low biodegradability and an acid pH. This boiling wastewater has no utility, being a serious environmental hazard. Anaerobic digestion is a promising technology for the treatment of organic effluents and for the simultaneous recovery of its energetic potential through methane production. Its application to cork effluents has never been subject of research. An anaerobic assay was conducted in order to determine the gas potential and biodegradability of the substrate using a mesophilic anaerobic consortium. Biodegradability batch experiments were performed at CBW concentrations of 3 and 6 kg COD m-3. The cork industry effluent was characterized (COD = 6.5 kg m-3; pH = 5.8). The liquid phase was analysed at the end of the experiment (pH, COD, total phenols). The methane accumulated in the vessels headspace was measured by gas chromatography. The maximum methane production was achieved after 15 days of experiment, and maintained until the end (44 days). The resultant methane potentials were 0.126 - 0.142 m3 CH4 kg-1 COD. The results suggest that CBW could be an interesting substrate for the anaerobic digestion process. The highest concentration (6 kg COD m-3) did not inhibit or significantly influenced the methane production. Concluding, a novel approach for the treatment and valorisation of the cork boiling effluent was revealed. The results demonstrate that the effluent from cork boiling can be treated and valorised by anaerobic digestion.