The utilization of rice straw for biofuel production is limited by its composition. The pretreatment process is required to improve the enzymatic accessibility of polysaccharides in the biomass prior to enzymatic saccharification. In this study, simultaneous biological pretreatment and saccharification (SPS) of rice straw starting from laccase production by Panus neostrigosus I9 was operated in a 2-L fermenter. It was found that fungal physiology was strongly influenced by the agitation, and that the highest laccase production was obtained at an agitation speed of 750 rpm (209.96 ± 0.34 U/L). The dilution rate of 0.05 h−1 was set in continuous fermentation which resulted in laccase activity of 678.49 ± 20.39 U/L, approximately three times higher than that in batch culture. Response surface methodology (RSM) was applied to achieve the condition for maximum percentage of delignification. The maximum percentage of delignification of 45.55% was accomplished after pretreatment of rice straw with laccase enzyme 39.40 U/g rice straw at 43.70 °C for 11.19 h. Reducing sugar of 3.85 ± 0.15 g/L was obtained from the digested rice straw in a SPS reactor, while non-pretreated rice straw gave only 1.13 ± 0.10 g/L within 12 h of incubation. The results indicated that simultaneous biological pretreatment and saccharification (SPS) of rice straw by laccase helped to improve the accessibility of cellulose by cellulolytic enzymes.
This research investigates the quality changes during composting of bagasse and pig manure amended with 30% of surfactantcoated charcoal (SC). Two treatments, 30% uncoated charcoal (UC) amendment and no charcoal (NC) amendment, were done as control. Charcoal was coated with 0.37 mM tetradecyltrimethylammonium bromide (TDMA), a cationic surfactant, at the dosage of 10 g/L. At the end of the composting period, the carbon to nitrogen (C/N) ratio of SC amendment was 9.7; whereas, the C/N ratios of UC and NC amendment were 12.6 and 21.4, respectively. Plant nutrients contents of the compost produced from SC amendment were 20.7 mg NH 4 + -N/g, 42.8 mg NO 3 --N/g, and 41.7 mg P/g. High nitrate and phosphate concentrations in SC amendment were due to the adsorption of these anions on the positive charge of TDMA. Desorption of plant nutrients retained in the compost pellets was also investigated. It was predicted that nitrate was fully desorbed from a pellet at 23 days for SC amendment, which was later than UC (14 days) and NC (10 days) amendment. A slow release of nitrate from the compost pellet will reduce the nitrate leaching into the environment. Thus, the adding of SC in the compost pile is one of the alternative methods to improve the quality of compost and plant nutrient retention.
Marine shrimp culture is important in agricultural sector which generates income for farmers. If marine shrimp culture is not proper management, it can cause environmental impacts on coastal ecosystem and water quality. Some areas use water spraying, washing and then flushing the pond bottom after shrimp harvesting and discharge water to receiving water which high nutrient and suspended solids exceeded the effluent standard. This research studied the marine shrimp discharge filtration using different media derived from palm shell. Three different media types for wastewater filtration were palm shell biochar (B), raw palm shell (R) and palm shell mixed with palm shell biochar (volume ratio of 1:1) (M). The simulated wastewater was daily fed via the top of the filter in semi-continuous mode (8 hours/day) at the hydraulic retention time of 4 h. During the 54 days of operation, water sample was collected to analyse SS, BOD, NH3-N, TP and FCB. At day 54th of operation, the average suspended solids (SS) removal efficiencies of B, R and M were 84, 82 and 84%, respectively, and the average total phosphorus (TP) removal efficiencies were 33, 28 and 30%, respectively. All filters could remove ammonia on the first 30 days of operation in which the concentration met the standard requirement of <1.1 mg/L. The average influent biochemical oxygen demand (BOD) concentration of 27 mg/L can be reduced to less than 20 mg/L after 3 days of operation in all filters. In addition, all filters were able to reduce the fecal coliform bacteria (FCB) to a lower concentration. Thus, these three different media are environmentally friendly material that can be used for effluent water filtration in the small-scale shrimp farm.
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