Nanofiltration of wastewaters from the fish meal industry

Abstract

The wastewaters generated in the fish meal industry, a water-intensive industry, contain a high organic load comprising a significant amount of proteins. Therefore, they should not be discharged without a suitable treatment in order to prevent negative impacts in the environment, and allow the recovery of high added value products. The effluent generated in a fish meal plant located in Talcahuano, Chile, was characterized, and pre-treated by microfiltration (MF) cartridges in series (80, 20 and 5 μm). A multi-channel ceramic membrane of 1 kDa MWCO, Kerasep NanoN01A, was used in the nanofiltration (NF) experiments. The operating conditions were optimised in total recycling mode, and the subsequent concentration experiment was carried out at 4 bar, 4 m/s, ambient temperature and natural pH. The results from this work clearly show that NF is an efficient and ecologically suited environmental technology for decontamination and recycling of the wastewaters generated during the fish meal production, as it allows both the recycle of water (permeate stream) and proteins (concentrate stream) into the fish meal process, besides environmental pollution abatement. Although the membrane undergoes severe fouling, it can be effectively cleaned through a basic-acid washing cycle.