Currently, heavy metal-contaminated groundwater is an environmental concern. This study investigated the use of bamboo biochar, chitosan-impregnated biochar, and iron-impregnated biochar for arsenic, iron, and manganese removal from groundwater. Isotherms of arsenic, iron, and manganese adsorption by bamboo derived biochar were compared with those of commercial activated carbon in simulated groundwater composed of single and trinary heavy metal solutions. The binding of heavy metals by virgin and loaded bamboo biochar and activated carbon was also investigated by sequential extraction. Chitosan and iron-impregnated biochar had enhanced arsenic adsorption, but these sorbents turned the pH of solution acidic, while it was alkaline for activated carbon. Adsorption equilibrium times of arsenic and iron were faster for single than trinary heavy metal systems because less ion competition occurred at active sites. The Langmuir model fitted the adsorption data well. The maximum adsorption capacities of arsenic, iron, and manganese by bamboo biochar in trinary heavy metal system were 2.2568, 0.6393, and 1.3541 mg g−1, respectively. The main mechanism for arsenic removal was precipitation with iron. Bamboo biochar bound iron in organic and sulfide fractions and manganese with iron-oxide. Bamboo biochar can replace activated carbon as a more efficient and sustainable carbonaceous sorbent material for removal of mixed heavy metals from groundwater within acceptable pH ranges.
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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