Cellulolytic Microflora Pretreatment Increases the Efficiency of Anaerobic Co-digestion of Rice Straw and Pig Manure
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Cellulolytic Microflora Pretreatment Increases the Efficiency of Anaerobic Co-digestion of Rice Straw and Pig Manure Fei Shen 1 & Bin Zhong 1 & Yanling Wang 1 & Xiang Xia 1 & Zhijun Zhai 1 & Qinghua Zhang 1
# Springer Science+Business Media, LLC, part of Springer Nature 2019
Abstract Agricultural wastes have severely polluted the environment and obstruct the sustainable development of modern agriculture due to a lack of effective disposal methods. The present study conducted batch experiments in which rice straw (RS) and pig manure (PM) mixtures were pretreated with a previously developed cellulolytic microflora prior to their mesophilic anaerobic codigestion. Optimal anaerobic digestion (AD) performance of RS and PM could be achieved after biological pretreatment with this specific cellulolytic microflora for 30 h. Under this condition, the filter paper cellulase (FPase) and carboxymethyl cellulase (CMCase) activities in RS and PM degradation broths reached maxima of 2.25 and 2.58 IU/mL, respectively, and the weight loss ratio reached 39.4%. After the subsequent AD process, the methane yield of RS and PM mixtures reached 263.69 mL/g-VS, which was 47.6% higher than that of the control group (CK) without biological pretreatment (178.66 mL/g-VS). In addition, the daily methane production peak duration (3 day) of the anaerobic co-digestion of RS and PM after 30 h of biological pretreatment with this microflora was longer than that of CK (1 day). The above results further indicated that pretreatment of RS and PM mixtures with microflora greatly enhanced the methane yield and prolonged the peak period of methane production in the subsequent anaerobic co-digestion. Keywords Agricultural wastes . Lignocellulose . Biofuel . Methane yield
Introduction Rice straw (RS) and pig manure (PM), two typical agricultural wastes with rich biomass, are extensively generated during agricultural production processes. However, direct discharge of these wastes will not only severely pollute the environment (i.e., causing declined air quality, water eutrophication, acceleration of the spread of infectious diseases, and destruction of the soil structure) but also waste lignocellulosic resources [1]. Therefore, it is necessary to identify appropriate disposal methods for these agricultural wastes. Currently, anaerobic digestion (AD) has attracted increasing attention due to its virtues of clean energy production, low energy consumption, and its benefit for environmental protection [2–4]. In general, AD can be divided into four stages: hydrolysis, acidogenesis, acetogenesis, and methanogenesis, where hydrolysis is
* Qinghua Zhang [email protected] 1
Jiangxi Engineering Laboratory for the Development and Utilization of Agricultural Microbial Resources, College of Bioscience and Bioengineering, Jiangxi Agricultural University, Nanchang 330045, People’s Republic of China
typically regarded as the main rate-limiting step of the AD, especially with regard to AD of granular solid substrates [5]. Moreover, lignocellulose biomass is mainly compos
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