MNPs were prepared using coprecipitation method, with FeCl₃, FeCl₂ and ammonia. MNPs were compounded with excess sludge (moisture content of 99%) to prepare magnetic excess sludge (MES). Alternating gradient magnetometer was used to measure the magnetic response of MES and scanning electron microscope (SEM) to observe morphology of excess sludge and MES. After magnetic separation, the water content of MES was calculated to investigate the degree of sludge thickening. The adsorption property of total phosphorus onto MES was investigated. According to the results, MES had superparamagnetism, and its saturation magnetization was 42 emu/g. Within 30 s it could be separated from liquid. The optimal conditions for adsorption of total phosphorus on MES were the initial pH value of solution ranging in 4-6, an initial concentration of phosphorus solution of 16 mg/L (calculated as P), adsorption equilibrium was achieved within 600 min. The kinetics data were fitted well with the pseudo-second order model. The adsorption fitted the Langmuir isotherm well with the equilibrium data and the theoretical maximum adsorption capacity was 3.00 mg/g (calculated as P). MES could accelerate the separation of sludge and wastewater, and the volume of excess sludge was reduced largely. The adsorption performance of total phosphorus on MES was better than that on excess sludge. The study provided a new handling method of excess sludge for sewage treatment plant whose secondary treatment process was activated sludge process.

An iron-doped (using limonite as the source of iron) cathode with PEI/MWCNT (polyethylenimine/ Multi- walled carbon nanotube) modified carbon felt outer layers was prepared for Electro-Fenton systems. PEI/MWCNT multi-layers could significantly increase the production of H₂O₂. The highest H₂O₂ accumulation was achieved up to 66.5 ± 2.4 mg/L at -0.95 V, neutral pH and 200 mL/min of aeration rate, which increased about 56.8% than the carbon felt at the same condition. The PEI/MWCNT multi-layers were stable enough that there was no obvious decrease in H₂O₂ accumulation after 20 recycles. This study tested the performance of the prepared cathode in treating the simulated dyeing wastewater. The results were as follows: Orange II with initial concentration of 20 mg/L at neutral pH (pH₀=6-7) was discolored completely after 60 min electrolysis process, and the decolorizing efficiency was up to 96.8%. In addition, the prepared cathode was stable enough and could be reused without catalytic activity decrease. This study also tested the performance of the prepared cathode in treating the actual dyeing wastewater. The chroma, COD and ammonia-nitrogen removal efficiency after 120 min electrolysis process were 91.7%, 69.4%, and 56.2% respectively.

A solid electrode with Cu(Ⅱ) was prepared by utilizing chitosan modified electrode to adsorb Cu(Ⅱ) in the solution, which was used as the cathode of microbial anode and chitosan modified cathode based battery (MACMCB). Different Cu(Ⅱ) masses and external loadings were tested to study the discharge property of MACMCB system. Results indicate that better discharge process relies on a larger amount of Cu(Ⅱ) or a higher external loading in this work. The highest cell voltage is 0.6346 V. The Cu(Ⅱ) reduction efficiency of MACMCB system is higher than 92.75%, indicating a nearly complete reduction of Cu(Ⅱ). The comparison between MACMCB and MFC indicates that MACMCB showes better performance than MFC on substrate consume and electricity output within a period of time. Changing the solid electrode within 10 - 30 hours is recommended. CuSO₄ is directly adsorbed inside the solid electrode. The major reduction product is copper, while the left included Cu₂O, phosphide of copper and chloride of copper.