Methods to alleviate the inhibition of sludge anaerobic digestion by emerging contaminants: a review

Abstract

The rising occurrence of emerging contaminants in sludges both inhibits the anaerobic digestion of sludges and induces health issues when sludges are recycled in agriculture, calling for methods to remove contaminants. Here we review emerging pollutants in wastewater treatment plants, before and after anaerobic digestion. We present their inhibitory effects and remediation methods to alleviate inhibition. Pharmaceuticals have been detected in about 50% of the sludge samples. Sewage sludge contaminants include 19% of diuretics, 16–21% of lipid-modifying agents, hydrochlorothiazide, diclofenac, furosemide, clarithromycin, atorvastatin, and carbamazepine. Levels of antibiotics, azithromycin, ciprofloxacin, and estrone range from 500 to 600 ng/g in sludges from wastewater treatment plants. Remediation methods comprise electrooxidation, ultrasonication, thermal hydrolysis, ozonation, and bioaugmentation. Fermenting the sludges with acidogenic bacteria reduces the level of emerging pollutants in the supernatant. Nonetheless, liquid digestates still contains emerging pollutants such as sunscreen octocrylene at 147 ug/L and acetaminophen at 58.6 ug/L. As a result, pretreatment of sludge containing emerging pollutants is required.

Effect of Emerging Micropollutants on the Anaerobic Digestion of Sewage Sludge

“…The concentrations of pharmaceuticals in municipal sewage sludge are lower; they barely reach 100 µg/L. The total content of pharmaceuticals in sewage sludge included diuretics (19%), lipid-modifying agents (16-21%), diclofenac, hydrochlorothiazide, clarithromycin, furosemide, atorvastatin, and carbamazepine [51]. The mean concentrations of selected pharmaceuticals in sewage sludge applied to agricultural land were 125 µg/kg d.w. [53].…”

Artificial intelligence for waste management in smart cities: a review

“…Based on the waste sources, research has demonstrated that industrial waste is the primary source of waste (Gaur et al 2020 ). This waste is mainly composed of volatile compounds, wastewater, slag, and scrap generated during industrial production, which contain many hazardous substances, such as heavy metals, organic pollutants, and radioactive materials, leading to severe environmental pollution (Patel et al 2022 ; Tawfik et al 2022 ). Additionally, organic waste is generated by agricultural, animal, and wastewater treatment waste and the food industry.…”

Forward Osmosis Application for the Removal of Emerging Contaminants from Municipal Wastewater: A Review

“…However, the appearance of emerging contaminants in sludge can eventually inhibit anaerobic digestion and can induce health problems when sludge is recycled to agriculture, requiring methods to remove contaminants either before or after anaerobic treatment. Some of the pollutant remediation methods include electrooxidation, ultrasonication, thermal hydrolysis, ozonation, and bioaugmentation [ 191 ]. Concurrently, a diluted DS would be obtained, which, depending on its composition and intended application, can be regenerated, subjected to desalination processes to yield clean or potable water, or even utilized directly as fertilizer for irrigation purposes.…”