Image analysis application for the study of activated sludge floc size during the treatment of synthetic and real fishery wastewaters

摘要

Background, aim, and scope Fishery wastewater treatmentcan be compromised due to seasonal production. The use ofsequencing batch reactors is not completely successful,despite flexibility being one of the principal advantages.Most research on activated sludge is performed usingsynthetic wastewater to ensure a stable and constant feed.The current work compared biomass morphology andsettling ability using image analysis of synthetic and realfishery wastewaters, with and without NaCl addition.Results The final effluent presented higher turbidity forboth wastewaters after NaCl addition, and lower SVIvalues. For synthetic wastewater, NaCl addition led to thetotal aggregates' area (TA) increase from 1.46 to 2.09 mm2/μL, alongside the growth of intermediate aggregates intolarger aggregates. The addition of NaCl to the fisherywastewater led to a decrease of the TA from 4.43 to1.72 mm2/μL. The biomass composition decreased in largerand intermediate structures, opposite to the smaller aggregates'area percentage increase.Discussion NaCl addition to synthetic wastewater incitedflocculation increasing sludge settling ability. A slightaggregate disruption was responsible for a turbidityincrease. A strong deflocculation was identified in fisherywastewater with NaCl from the decrease of intermediateand large aggregates. This contrasted with pinpoint flocsrelease, which increased the turbidity levels.Conclusions, recommendations, and perspectives It couldbe established that synthetic wastewater biomass flocculationand fishery wastewater biomass deflocculation, observedduring 0.5% NaCl experiments, were related tosludge settling and effluent turbidity changes. Furthermore,the biomass changes obtained with synthetic wastewatercannot be extrapolated to fishery wastewater.