Anaerobic digestate: pollutants, ecotoxicology, and legislation

Abstract

Anaerobic digestion (AD) offers enormous potential towards a sustainable bioeconomy. AD is suitable for waste management of various sources and generates value in multiple sectors such as electricity, heating, or agriculture through biogas or fertilizer production. However, attention must be paid to cheap fertilizers such as digestates because these digested fractions contain heavy metals, (nano) microplastics, hormones, and other chemical compounds that, when accessible, can be detrimental to humans, animals, plants and the environment. Digestates originating from manure substrates should be monitored to control the spread of antimicrobial resistance genes to the environment. Digestate toxicity can be a problem for aquatic and terrestrial organisms as determined by bioassays to detect the adverse consequences of digestate applied to the soil. Anaerobic digestate must meet specified quality requirements prior to utilization in the soil or crops to prevent dangers to human health and the environment. The digestate is available in three forms: whole, liquid, and solid, and can be applied to the soil as a final disposal location if it complies with applicable regulatory standards and is classified as a ‘product’