Evaluation of Biological Degraded Keratin for Biogas Production Using Dry Anaerobic Digestion System

Anaerobic digestion is a methane gas production process that can be used as sustainable alternative energy. Anaerobic digestion utilized various types of organic waste as substrate for the reaction process. Keratin waste is an organic waste mainly produced from the poultry and farming industry. Pretreatment is usually required to hydrolyzed keratin protein complex as the amino acid is easily used as the substrate in anaerobic digestion reaction. Biological pretreatment was selected because it more energy saver and generating diverse types of amino acid monomers. Three types of keratins used in this research were feathers, wool, and hair. Culture of Bacillus sp. C4 were inoculated into keratins and incubated for 24 hours, 48 hours, and 72 hours. The chicken feathers produce the soluble protein as much as 7.23 mg/ml, 32.59 mg/ml and 45.99 mg/ml respectively, while the sheep wool produce 24.08 mg/ml, 36.73 mg/ml and 38.75 mg/ml respectively according to incubation time. Meanwhile, keratin hair cannot be degraded by Bacillus sp. C4 at all. Free ammonia formed by hydrolysis of proteins is suspected to be an inhibitor in the methanogenesis process, as total methane produced from degraded keratin only 256,6 ml C4/gr VS in 36 days retention time

Dry Anaerobic Digestion of Food and Paper Industry Wastes at Different Solid Contents

A large volume of food is being wasted every year, while the pulp and paper industry also generate a large amount of solid wastes on a daily basis, causing environmental challenges around the world. Dry anaerobic digestion (AD) of these solid wastes is a cost-effective method for proper management. However, dry digestion of these waste streams has been restricted due to their complex structure, the presence of possible inhibitors and inappropriate operating conditions. In light of this fact, dry digestion of food waste (FW) and paper wastes (PW) was conducted at different total solid (TS) concentrations of reactor mixtures of 14%, 16%, 18% and 20% TS, corresponding to substrate to inoculum (S/I) ratio of 0.5 and 1; investigating the optimum operating conditions for effective dry digestion of these complex wastes. The highest methane yields of 402 NmlCH(4)/gVS and 229 NmlCH(4)/gVS were obtained from digestion of FW and PW, respectively at 14%TS corresponding to an S/I ratio of 0.5. Increasing the S/I ratio from 0.5 to 1 and thereby having a TS content of 20% in the reactor mixtures was unfavorable to the digestion of both substrates

Dry Anaerobic Co-Digestion of Citrus Wastes with Keratin and Lignocellulosic Wastes : Batch And Continuous Processes

Dry anaerobic co-digestion of citrus wastes (CW) with chicken feather (CF), wheat straw (WS) and manure bedded with straw (MS) was investigated in batch and continuous processes. Experiments were designed with different mixing ratios considering the inhibitory effect of CW, C/N ratio, and total solid content of individual feedstocks. Best mixing ratio (CF:CW:WS:MS) of 1:1:6:0, enhanced methane yield by 14% compared to the expected yield calculated according to the methane yields obtained from the individual fractions. The process performance of this mixture was then investigated in continuous plug flow reactors at different organic loading rates (OLR) with feedstock total solid contents of 21% TS (RTS21) and 32% TS (RTS32). At OLR of 2 gVS/L/d, a methane yield of 362 NmlCH4/gVSadded was obtained from RTS21, which is 13.5% higher than the yield obtained from RTS32 (319 NmlCH4/gVSadded). However, it was not possible to achieve a stable process when the OLR was further increased to 3.8 gVS/L/d; there were increased total VFAs concentrations and a decline in the biogas production

Dry fermentation of manure with straw in continuous plug flow reactor : Reactor development and process stability at different loading rates

In this work, a plug flow reactor was developed for continuous dry digestion processes and its efficiency was investigated using untreated manure bedded with straw at 22% total solids content. This newly developed reactor worked successfully for 230days at increasing organic loading rates of 2.8, 4.2 and 6gVS/L/d and retention times of 60, 40 and 28days, respectively. Organic loading rates up to 4.2gVS/L/d gave a better process stability, with methane yields up to 0.163LCH4/gVSadded/d which is 56% of the theoretical yield. Further increase of organic loading rate to 6gVS/L/d caused process instability with lower volatile solid removal efficiency and cellulose degradation.[on SciFinder (R)]MEDLINE AN 2017659917(Journal; Article; (JOURNAL ARTICLE))</p

Effect of anaerobic digestion of manure before application to soil – benefits for nitrogen utilisation?

Purpose Anaerobic digestion produces renewable energy, biogas, from organic residues, but also digestate, a valuable organic fertiliser. Previous studies have indicated that digestate contains ample plant available nitrogen (N), but there are also concerns about greenhouse gas (GHG) emissions after application of digestates to soil. The aim of this study was to compare digestate and undigested feedstock for fertiliser effect as well as greenhouse gas emissions during the next season. Methods Digestate and its feedstock, manure, were compared as N fertilisers for wheat. Mixing digestate with biochar before application was also tested. After harvest, soil samples were frozen and dried. Then GHG emissions immediately after a re-wetting of dry soil and after thawing of frozen soil were measured to determine emissions after a non-growing season (dry or cold). Results All N in digestate was plant available, while there was no significant N fertiliser effect of the undigested manure. N2O emissions were higher after a dry season than after freezing, but the undigested manure showed higher emissions during thawing than those detected during thawing of soils from any of the other treatments. Conclusion Anaerobic digestion makes N available to plants, and when residues with much N that is not plant available the first season are used, the risk of N2O emission next spring is high