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Methane-yielding microbial

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**Chapter 7**

**Abstract**

**1. Introduction**

Heavy Metals

Biodegradability during Anaerobic

Fermentation Process Impacted by

In the past decades, biotechnologies for reutilizing the biomass harvested from

the metal-contaminated land draw attention to many scientists. Among those technologies, anaerobic fermentation is proven as an efficient conversion process for biowaste reduction with simultaneous recovery of biogas as an energy source. During the process of anaerobic fermentation, the release of metals from the biomass will impact the growth and performance of microorganisms in reactors, which then results the variation of substrate degradation. In this chapter, the impact of metals on the degradation of substrate at different stages of fermentation process, as indicated by variations of lignocelluloses, chemical oxygen demands (COD), volatile fatty acids (VFAs), etc., will be summarized. The objective is to rationalize the relationship between metal presence and substrate degradability and give sug-

gestions for future research on metal-contaminated biomass reutilization.

chemical oxygen demands, volatile fatty acid

ability in remediation systems [7].

**Keywords:** anaerobic fermentation, heavy metal, biodegradation, lignocelluloses,

The rapid development of industries such as electronic, mining, agrochemical, tannery, and battery industries has led to an increase in the direct and indirect discharge of metals into the environment. Some metals are potentially toxic, and unlike some organic contaminants, they are not biodegradable; thus, they may accumulate in terrestrial and aquatic organisms [1]. Hence, removal of potentially toxic metals (PTM) from contaminated environments has become an issue of urgent concern. In recent years, phytoremediation, which is defined as the use of plants to remove contaminants from contaminated environment, has drawn great attention probably because it is cost-effective and sustainable [2, 3]. However, disposing the biomass residues following phytoremediation is challenging [4–6]. Therefore, there has been a growing interest on the development of inexpensive disposal techniques and improvements in bio-resource utilization to foster sustain-

Anaerobic fermentation is a relatively efficient conversion process for biomass waste reduction with simultaneous recovery of biogas as an energy source [8–11]. In an anaerobic reactor, there are four processes that occur simultaneously, i.e., hydrolysis, acidogenesis, acetogenesis, and methanogenesis [12]. Hydrolysis

*Yonglan Tian, Huayong Zhang and Edmond Sanganyado*
