In a microbial bioelectrochemical system (BES) living microorganisms catalyze the anodic oxidation of organic matter at a low anode potential. We used a BES with a biological anode to power the cathodic recovery of Cu, Pb, Cd, and Zn from a simulated municipal solid waste incineration ash leachate. By varying the control of the BES, the four metals could sequentially be recovered from a mixed solution by reduction on a titanium cathode. First, the cell voltage was controlled at zero, which allowed recovery of Cu from the solution without an electrical energy input. Second, the cathode potential was controlled at -0.51 V to recover Pb, which required an applied voltage of about 0.34 V. Third, the cathode potential was controlled at -0.66 V to recover Cd, which required an applied voltage of 0.51 V. Finally, Zn was the only metal remaining in solution and was recovered by controlling the anode at +0.2 V to maximize the generated current. The study is the first to demonstrate that a BES can be used for cathodic recovery of metals from a mixed solution, which potentially could be used not only for ash leachates but also for e.g. metallurgical wastewaters and landfill leachates.
In this study, a bioelectrochemical reactor was investigated for simultaneous hydrogen production and ammonium recovery from reject water, which is an ammonium-rich side-stream produced from sludge treatment processes at wastewater treatment plants. In the anode chamber of the reactor, microorganisms converted organic material into electrical current. The electrical current was used to generate hydrogen gas at the cathode with 96±6% efficiency. Real or synthetic reject water was fed to the cathode chamber where proton reduction into hydrogen gas resulted in a pH increase which led to ammonium being converted into volatile ammonia. The ammonia could be stripped from the solution and recovered in acid. Overall, ammonium recovery efficiencies reached 94% with synthetic reject water and 79% with real reject water. This process could potentially be used to make wastewater treatment plants more resource-efficient and further research is warranted.
Hydrothermal carbonization of bamboo was conducted at 300-370 °C for 1 h. Products in solid, oil, aqueous and gaseous phases were collected and studied. More than 20% carbon was water-soluble. Oil phase was mainly hydroxylated derivatives of benzene. Hydrochars were composed of many microspheres in morphology, with carbon content of 72.1-81.0%. Around 50-60% of carbon in bamboo remained in hydrochars. High heating value of hydrochars was 1.3-1.6 folds of original bamboo. The hydrochars had higher antioxidative stability than pyrolysis biochar.
By testing water quality analysis of part of the import and export of wastewater pretreatment facility catering units in Kunming shows that these pre-processing facilities catering units emit water SS, COD, BOD5, Anionic Surfactants and Animal and Vegetable Oils compliance rate is not high, exceeded the phenomenon is more serious .It shows most pretreatment facilities catering units Kunming currently flawed,and these indicators can not be treated all the standards. Some pretreatment facilities of catering units should based on the test results improving and strengthen management.
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