Water recycling in textile industries: Effects on biological treatment plants

A potential limit for water recycling in industrial processes is the increase of compounds concentration in the remaining effluent whom biological treatability can be reduced. In this paper a procedure aimed at evaluating the compatibility of a recycling system with an existing WasteWater Treatment Plant (WWTP) is described. This is an objective of the LIFE funded project BATTLE (BAT for water reuse in TextiLE SMEs). The procedure is applied to a textile company (Stamperia di Martinengo srl, Bergamo, Italy) and its on-site biological WWTP. The effects of the water recycling scheme on the existing WWTP have been evaluated by means of an integrated approach of respirometric, titrimetric and physico-chemical analysis and the implementation of an ASM1 model for the simulation of biological processes. In this case titration trials did not reveal any inhibitory effect of neither biodegradable nor biodegradable compounds on biological processes for water recycling ratio up to 60%. Respirometric and titration tests allowed to successfully implement an ASM1 model which revealed that for recycling ratio up to 50% the COD and nitrogen limits, set by the Italian law for effluent discharge, were not exceeded.