Efficient co-conversion process of chicken manure into protein feed and organic fertilizer by Hermetia illucens L. (Diptera: Stratiomyidae) larvae and functional bacteria

Journal of Environmental Management Volume 217, 1 July 2018, Pages 668-676 Journal of Environmental Management Research article Author links open overlay panelXiaopengXiaoaLorenzoMazzaabYongqiangYuaMinminCaiaLongyuZhengaJeffery K.TomberlincJeffreyYudArnoldvan HuiseZiniuYuaSalvatoreFasulobJibinZhanga a State Key Laboratory of Agricultural Microbiology, National Engineering Research Center of Microbial Pesticides, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China b University of Messina, Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, Via F. Stagno D'Alcontres n.31, 98166 Messina, Italy c Department of Entomology, Texas A&M University, USA d Texas Academy of Mathematics and Science, University of North Texas 1155 Union Circle #311070, Denton, TX 76203-5017, USA e Laboratory of Entomology, Wageningen University & Research, Wageningen, The Netherlands Received 28 December 2017, Revised 17 March 2018, Accepted 29 March 2018, Available online 11 April 2018. crossmark-logo https://doi.org/10.1016/j.jenvman.2018.03.122 Get rights and content Highlights • Established efficient manure co-conversion process by black soldier fly and bacteria. • Gut bacteria could enhance manure conversion and manure reduction. • Co-conversion process could shorten the processing time of chicken manure. • Co-conversion could harvest high value-added larvae mass and biofertilizer. Abstract A chicken manure management process was carried out through co-conversion of Hermetia illucens L. larvae (BSFL) with functional bacteria for producing larvae as feed stuff and organic fertilizer. Thirteen days co-conversion of 1000 kg of chicken manure inoculated with one million 6-day-old BSFL and 109 CFU Bacillus subtilis BSF-CL produced aging larvae, followed by eleven days of aerobic fermentation inoculated with the decomposing agent to maturity. 93.2 kg of fresh larvae were harvested from the B. subtilis BSF-CL-inoculated group, while the control group only harvested 80.4 kg of fresh larvae. Chicken manure reduction rate of the B. subtilis BSF-CL-inoculated group was 40.5%, while chicken manure reduction rate of the control group was 35.8%. The weight of BSFL increased by 15.9%, BSFL conversion rate increased by 12.7%, and chicken manure reduction rate increased by 13.4% compared to the control (no B. subtilis BSF-CL). The residue inoculated with decomposing agent had higher maturity (germination index >92%), compared with the no decomposing agent group (germination index ∼86%). The activity patterns of different enzymes further indicated that its production was more mature and stable than that of the no decomposing agent group. Physical and chemical production parameters showed that the residue inoculated with the decomposing agent was more suitable for organic fertilizer than the no decomposing agent group. Both, the co-conversion of chicken manure by BSFL with its synergistic bacteria and the aerobic fermentation with the decomposing agent required only 24 days. The results demonstrate that co-conversion process could shorten the processing time of chicken manure compared to traditional compost process. Gut bacteria could enhance manure conversion and manure reduction. We established efficient manure co-conversion process by black soldier fly and bacteria and harvest high value-added larvae mass and biofertilizer. Previous article in issue Next article in issue Keywords Hermetia illucens L. larvae Functional bacteria Chicken manure reduction rate Feed stuff Organic fertilizer Waste management 1. Introduction Chicken production has increased due to the increasing demand for meat and eggs (Nie et al., 2015). Subsequently, massive amounts of chicken manure have been produced. Chicken manure is rich in readily biodegradable organic matter, nutrients, and pathogens. However, if poorly managed, chicken manure can become an important source of pollution (Wang et al., 2014, Nie et al., 2015). Manure is traditionally composted to kill pathogens and fertilize crops (Guerrini et al., 2017, Abreu-Junior et al., 2017). However, the low C/N ratio, high moisture content, nasty odor, long decomposition period, nutrient loss, and the formation of phytotoxic compounds have become challenges for current composting methods (Chang and Chen, 2010, Wang et al., 2013). Bulking agents, such as sawdust and rice chaff, are usually added to manure composts to reduce moisture and to achieve a suitable C/N ratio. However, these bulking agents have become increasingly expensive for composting as they are used as alternative energy resources (Chang and Chen, 2010, Zhu et al., 2012). For that reason, alternative means to convert chicken manure into fertilizer production should be explored. Many insects efficiently degrade organic waste into nutrients (Zheng et al., 2012, Čičková et al., 2015). Hermetia illucens L. (Diptera: Stratiomyidae), also known as black soldier fly (BSF), live outdoors and is often associated with livestock (Li et al., 2011). BSF can be found in decaying organic wastes, such as animal manure and plant material, and exhibits antimicrobial peptide activity against pathogens in those wastes (Liu et al., 2008, Lalander et al., 2015, Elhag et al., 2017). BSF not only reduces the accumulation of manure and the nasty smell, it also inhibits the proliferation of house flies (Zheng et al., 2013). These processes greatly reduce environmental impact caused by livestock manure. Zhou et al. (2013) found that black soldier fly larvae (BSFL) of the Wuhan strain weighed 14.4–37.0% more than the BSFL Guanghzhou strain and BSFL Texas strain, respectively. The BSFL Wuhan strain reduced dry matter 46.0% (swine), 40.1% (dairy), and 48.4% (chicken) more than the Guangzhou strain and 6.9%, 7.2%, and 7.9% more than the Texas strain. Gut microbes play important roles in insect nutrition and colonization resistance against invasion of exotic microbes (Dong et al., 2009). Bacteria isolated from the BSFL gut can increase the weight of prepupae and pupae, and shorten the number of days from hatching to the prepupal stage (Yu et al., 2011). Therefore, BSFL can be used as animal feed and for biodiesel production. The residue of the organic waste is a suitable substrate for aerobic fermentation during composting (Li et al., 2015, Rehman et al., 2017). Composting or aerobic fermentation accelerates the natural decomposition of organic debris by microorganisms (bacteria, actinomycetes and fungi) under controlled environmental conditions. Inoculation at the appropriate time can promote organic waste maturity and considerably shorten the period of decomposition (Zeng et al., 2010, Jurado et al., 2015). However, not much is known about the Insect-Bacteria-Manure digestion system in reducing manure pollution. In this study, we tried to develop an efficient and high-value co-conversion technology of chicken manure by BSFL and bacteria in a poultry farm. Our aim was to maximize BSFL harvest and waste mass reduction by using synergistic bacteria in the first stage and shorten the maturity time through inoculation with a decomposing agent to promote aerobic fermentation in the second stage. Important process parameters were monitored such as changes in: the conversion rate by the larvae; the reduction rate of chicken manure; physical and chemical properties; the occurrence of phytotoxicity, and the presence of microbial enzymes.