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This paper presents a scientific performance study of the application of the modified aquatic mat pond (MAMP)-integrated vertical-flow constructed wetland (IVCW) coupling process for treating micro-polluted river water using luffa sponge material. In addition, the surface modifications of luffa sponge were investigated. The results showed that luffa sponge functioned well in a bench scale experiment and in a demonstration project, and the main effluent water indexes reached the class IV standard defined by the surface water quality standard of China (GB3838-2002). However, natural luffa sponge is easily hydrolyzed and should be replaced at regular intervals. A microwave-enhanced KH550 (Silane coupling agent gamma-aminopropyltriethoxysilane) coupling method for modifying luffa sponges were performed to reduce the water absorption rate and prolong the engineering service time of the sponge. The results showed that the water absorption rate of the tested luffa sponge fibers was reduced to 22.39% after the fourth set of modifications, and an orthogonal test revealed that the priority order for the factors that affected the modification process was KH550 concentration >microwave reaction time >NAOH concentration > soaking time. The optimal set of modification conditions for luffa sponge fibers was 2% (w/w) NAOH, 1% (w/w) KH550, 30 min of soaking and 180 s of microwave treatment.

The aim of the study was to understand the releasing characteristics of sediment phosphorus (P) in all fractions under varying environmental conditions and the relationship between sediment P and eutrophication in shallow city lake, Donghu Lake of Wuhan in China. Effects of P concentration in overlying water, oxygen, light, pH, temperature, and agitation intensity on release processes of sediment P in all fractions in Donghu Lake, China, were investigated. The release quantity and release rate of sediment P in the distilled water were significantly higher than those of lake water, and under anaerobic condition, they were higher than those of aerobic treatment. The concentrations of each P form decreased obviously in both dark and irradiated systems. Both high and low pH promoted the release of Fe/Al-P, IP, and TP, but Ca-P decreased sharply with decreasing pH, while the difference of OP was not obvious. The release rate of each P form accelerated drastically when water temperature rose from 5 to 3...

Although micro-organisms play a significant role in pollutant removal in constructed wetlands, little is known on the effect of wastewater-quality properties on microbial characteristics. In this study, two groups of integrated vertical-flow constructed wetland microcosms were applied to treat synthetic domestic wastewater and synthetic secondary effluent. The effects of wastewater-quality properties on microbial features were assessed. Results showed that higher values of microbial indicators were observed in the systems with domestic wastewater and in down-flow cells. Redundancy analysis revealed that organic matter concentration and temperature were two critical determinants influencing the microbial features.

Nitrate removal rates of two pilot-scale integrated vertical-flow constructed wetlands (IVCWs) treating tail water, under a hydraulic loading rate (HLR) of 250 mm/d with a mean influent NO3--N concentration of 24.4 mg.L-1, were evaluated. Mean NO3--N removal efficiencies of 15.5 and 18.5% with mass removal rates of 1.01 g.m(-2).d(-1) and 1.16 g.m(-2).d(-1) for IVCW 1 (planted with Canna indica and Pontederia cordata) and 2 (planted with Typha orientalis and Arundo donax var. versicolor), respectively, were achieved. The removal rate constants as fitted by the first-order area-based model averaged 0.046 and 0.055 m.d(-1), respectively. Since NO3--N was the dominant nitrogen form in the effluent, denitrification was the limiting step in nitrogen removal despite of favorable pH and anaerobic conditions in the wetland beds. Low availability of carbon source, high HLR, and low temperature could be the probable influencing factors for the observed low NO3--N removal efficiencies. However, IVCW could be used to treat tail water for nitrate removal at a comparable high loading rate.

Phosphorus is one of the main causes for eutrophication in waterbodies. The techniques for phosphorus removal from wastewater and waterbodies have become a hot topic in the world. In this study, used brick was chosen as an experimental adsorbent for removing phosphorus from phosphate solution, and the effects of brick dosage, pH, temperature and vibration time on phosphorus adsorption characteristics were evaluated. Results showed that phosphorus could be effectively removed using brick powders, and the optimum brick dosages were 4, 9 and 35g/L in the presence of 5, 10 and 50mg/L of phosphorus concentrations, respectively. A significant linear correlation (R-2=0.9904) between phosphorus concentration and optimum brick dosage was observed. The optimum condition was determined to be: brick dosage 20g/L, phosphorus concentration 25mg/L, pH 5, temperature 25 degrees C and vibration time 2h.

Phosphorus is a crucial element in the eutrophication process. According to China’s water pollutant discharge Class 1A standard, treated wastewater must meet 0.5 mg/L of phosphorus prior to discharge to a sensitive water body. In recent years, wastewater treatment technologies such as membrane bioreactors have been demonstrated to achieve high-quality effluent and present the potential for wastewater reuse applications. However, an efficient and cost-effective phosphorus removal process is still not warranted. In this study, a submerged membrane bioreactor (SMBR) with addition of a low concentration of aluminum sulfate ([mol Al : mol P ≤ 1] was used to evaluate its treatment performance. The results showed that significant phosphorus removal could be achieved with addition of a low aluminum sulfate dosage to meet national phosphorus discharge standard; however, no significant effect was observed on the removal of COD and ammonia. The addition of a low concentration of aluminum sulfate could offer as an economical solution to increase the phos phorus removal efficiency of a SMBR, and thereby improve the water quality of the water bodies.