Physico-chemical pretreatment and fungal biotreatment for park wastes and cattle dung for biogas production

With the rising demand for renewable energy and environmental protection, anaerobic digestion of biogas technology has attracted considerable attention within the scientific community. The effect of physico-chemical pretreatment on cellulose degradation followed by fungal treatment by Aspergillus terreus and Trichoderma viride to treat cellulosic biomass for enhancing its digestibility was investigated. The tested substrate was digested with and without physical, chemical, and biological treatment. Fresh leaves, dry leaves and cattle dung were characterized by a total solids content 35, 84 and 17 %, volatile solids content 81.2, 59.49 and 64.5 % and C/N ratio 31, 45.4 and 13.6, respectively. Biogas total volume was determined using water replacement technique, while methane volume was determined using precipitation of CO(2) in 20 % NaOH solution. Pretreatment steps were carried out by using mechanical and chemical pretreatments using 2.5 % NaOH mixed with 2.5 % NH(4)OH for 15 days, followed by biological treatment of A. terreus and T. viride. The potential of pretreatment of substrate was studied at regular intervals of 0, 7, 14, 21, 28, 35, 42, 49, 56, 63 and 70 days determining the change in chemical and physical compositions of used substrates. Biogas production was 102.6 and 125.9 L/KgVS from untreated and pretreated substrate, respectively. On the other hand, methane production was 61.4 and 79.8 L/KgVS from untreated and pretreated substrate, respectively. In conclusion, Physical (milling), chemical (NaOH and NH(4)OH) pretreatment in addition to fungal (A. terreus and T. viride) treatment for the tested substrate prior to AD was an efficient process for improvement of biogas and methane production. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40064-015-1466-9) contains supplementary material, which is available to authorized users.