Anaerobic treatment of sulfate-rich wastewaters: process modeling and control

Abstract

A variety of anthropogenic activities, especially at industrial level, generate wastewater streams rich in sulfate which, if improperly treated, can cause health, social and environmental problems (Serrano et al., 2020). These industrial activities include food production (e.g. edible oil, seafood-processing), fermentation industry, tanneries, coal-burning power plants, paper and pulp industry, mining and metallurgical processes. Additionally, in some regions (e.g. Hong Kong), the use of seawater for toilet flushing to alleviate the pressure on potable water has increased the sulfate concentration in municipal sewage (Li et al., 2018; Wu et al., 2016). Anaerobic digestion (AD) is a well-established technology to transform municipal and industrial organic-rich wastewaters into renewable energy in the form of methane-rich biogas. Besides energy recovery, AD presents other important advantages compared to aerobic treatment such as low sludge production and low energy requirements (Puyol et al., 2017). AD is also a suitable technology to treat organic-rich municipal and industrial wastewaters containing sulfate. However, a high sulfate content can affect the AD process performance and feasibility due to (i) the competition for easily biodegradable organic matter (e.g. short chain fatty acids, hydrogen) between sulfate reducers and anaerobic microorganisms (Cassidy et al., 2015; Kalyuzhnyi et al., 1998), (ii) the generation of H 2 S, the product of sulfate