Impact of professional cleaning agent used in fish-canning industry in wastewater treatment

Abstract

Fish-canning industry represents an important and denoting industry both in Portugal and in the EU. It is estimated that 20 Portuguese industries produced in 2013 approximately 47 thousand tonnes of fish canned commodities, generating 234 million [1, 2]. To maintain food safety standards, the use of biocides in the fish-canning facilities cleaning procedures is mandatory [3]. One of the biocides used is the commercial DEPTAL MCL (HYPRED), a chlorine alkaline liquid. DEPTAL MCL disinfectant action within the fish-canning industry is recognized and is approved by the European Union regulation number 1272/2008. Due to the quantities required for the effective and systematic disinfection of a fishery facility, considerable amounts of biocide may reach the wastewater treatment plants (WWTP). Being biological activated-sludge WWTP the most common facilities to treat these wastes worldwide, the biocides may affect their biological communities, thus affecting the overall performance of the plants [4]. To test the potential impact of DEPTAL MCL in the WWTP, two lab-scale plants were used. Both the activated sludge and the influent used were collected from a municipal WWTP. Three different concentrations of DEPAL were tested: 1 mL, 0.5 mL and 0.1 mL DEPTAL per g L-1 of volatile suspended solids. Several physicochemical and biological parameters were analysed to allow for the assessment of the biocidal effect on the biological community and the WWTP performance. The results show a significant and persistent effect of DEPTAL in the biological community and a severe decrease in the performance of the wastewater treatment.