Treatment of wastewater coming from culture of scallop Argopecten purpuratus using O3/photo-Fenton and membrane distillation processes

Abstract

The treatment and recovery of industrial wastewater is a necessary contribution to solve the water scarcity problems that affect an increasing part of the world’s population. One of the industries that produces a larger amount of polluted wastewater is aquaculture, where water is used to wash the biofouling from the culture systems. The aim of this research is the evaluation of the use of a treatment line consisting on coagulation/flocculation-filtration, advanced oxidation by ozone/solar photo-Fenton, and membrane distillation (MD) to treat wastewater coming from the wash of a Chilean aquaculture facility of the scallop Argopecten purpuratus. The technologies were arranged in series, with the feed water to the MD process being the remaining wastewater from the previous sequential stages. The pretreatment reduced the total suspended solids (TSS) from 204.7 to 15.4 mg/L, the chemical oxygen demand (COD) from 6236.2 to 2993.3 mg/L and the colour from 205.4 to 109.4 Platinum Cobalt Units (PCU), with a removal of 92%, 52% and 46.7%, respectively. The ozone/solar photo-Fenton process further reduced the COD and the colour to 448.7 mg/L and 18.7 PCU, respectively. Finally, the resulting wastewater was treated with MD to remove the pollutants still present. Permeate flux was almost constant around 18 L/h/m2, and no permanent fouling layer was observed during the MD treatment. Total Organic Content in the permeate was reduced from 166.2 mg/L to 5.2 mg/L, which is equivalent to a COD reduction from 448.7 to 14 mg/L. The integration of the pretreatment stages, the ozone/solar photo-Fenton process and the MD process allows to achieve a significant removal of the pollutants present in the wastewater, being thus a very useful strategy for dealing with the climate crisis and water scarcity.