Towards a “crippled-mode” operation of an industrial wastewater treatment plant

Abstract

In house treatment of metal plating wastewater mainly involves chemical treatments performed in continuous flow stirred tank reactors (CFSTR). The inflow of these tanks is directly produced by the plating shops activity, and the storage capacity never exceeds a few hours of incoming flow. Thus, any fault on one of the CFSTR may impose a complete stop of the whole manufacturing process, which is unacceptable for the manufacturer. Another solution would be having "spare" CFSTRs ready to be used as alternative in case of any CFSTR fault or maintenance. The latter solution however implies additional costs in equipment, storage space and maintenance so as to keep this equipment fit and ready for operation. The paper presents the study of a "crippled-mode" wastewater treatment (WWT) operation which enables a sufficiently efficient working of the WWT plant during maintenance phases and failure repairing on any of the CFSTR, without any extra equipment needed. This survey has been performed on real industrial WWT plants, with a continuous influent and under industrial operation constraints. The performances of the detoxication have been analysed when a CFSTR is short-circuited and the corresponding chemical treatment is shunt in the upstream or downstream CSFTR. This work shows the possibility of satisfying the environmental regulations with a WWT plant functioning under subnormal conditions.