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Increased pollution caused by socio-economic development has led to compound-contaminated high-hardness water pollution. In this study, laboratory-scale nanofiltration (NF) treatment of such water was investigated. Response-surface methodology was used to optimize the NF operating parameters, and a regression model with desalination rate and transmembrane pressure changes as response values was established. The NF membrane efficiencies in contaminant removal from groundwater and surface water with compound-contaminated high hardness and the membrane-fouling characteristics during long-term operation were investigated. The results show that the optimal operating parameters for the NF membrane in the removal of inorganic salts from groundwater are as follows: influent pH 8, influent pressure 1 MPa, and water yield 27.976%. The removal rates for groundwater total hardness, total alkalinity, total soluble solids, K+, Na+, Ca2+, Mg2+, , Cl−, , and were 99.4, 90.3, 84.7, 63.2, 56.8, 99.6, 95.2, 99.6, 68.3, 86.1, and 65.9%, respectively. Surface water contains more complex components; therefore, membrane fouling during surface water is more serious. The NF membrane was operated continuously for more than 35 days under the optimal operating conditions with no serious membrane fouling. HIGHLIGHTS Response-surface methodology was used to optimize the NF operating parameters.; NF membrane was operated continuously for more than 35 days under the optimal operating conditions with no serious membrane fouling.; The membrane fouling by hardness ion was analyzed by SEM-EDS.

As the water diversion reservoir showed high organic matter and high algae in summer, the potassium permanganate pre-oxidation/dissolved air flotation/carbon sand double filter process was developed. The test results show that the optimum operation conditions of the combined process were as follows: the dosage of KMnO4 was 0.3 mg/L, the dosage of polymeric aluminum ferric chloride (PAFC) was 3.0 mg/L (Al3+), the reflux ratio was 10%, and the dissolved gas pressure was 0.3 Mpa. Taking Ji'nan Queshan reservoir water algae pollution as the research object, the average removal rate of chlorophyll a, blue-green algae, turbidity, particle number and total organic carbon (TOC) reached 66.64%, 95.44%, 94.45%, 99.34% and 46.68%, respectively; the methylisoborneol (MIB) removal rate was 92.47%, the odor level decreased with process flow from raw water level 4 to effluent level 1.5, geosmin (GSM) dropped below the detection limit, and the total removal rate of trihalomethane formation potential (THMFP) was 33.56%. The effluent of the combined process meets the requirements of the Hygienic Standard for Drinking Water (GB5749-2006) after it is disinfected.

This study is to investigate the behavioural responses of zebrafish to the toxic effects of waterborne zinc and chromium(VI). Swimming performance of fish was tracked by a real-time toxicity bio-monitoring system and transformed into data to calculate individual and fish school behavioural endpoints. Behavioural responses under metals were in accordance with the Stepwise Behavioural Response model. Significant and concentration-dependent effects on swimming speed and turning times were found at concentrations equal to or higher than 3.5 mg L-1 for zinc and 0.7 mg L-1 for chromium. Swimming height significantly declined in concentrations equal to or higher than 3.5 mg L-1 under zinc exposure, while for the chromium treatment, it significantly increased in lower concentration exposures and decreased in higher concentration exposures. Average distance and dispersion of fish school decreased at the beginning but there were no obvious changes during the whole exposure period. Behavioural responses unde...

Countercurrent–cocurrent dissolved air flotation (CCDAF), the popular water purification device, which consists of collision and adhesion contact zones, showed favorable flotation conditions for micro-bubble adhesion and stability. In this study, computational fluid dynamics (CFD) numerical simulation was employed to confirm that the unique CCDAF configuration create reasonable and that the flow field characteristics were good no matter for single phase or gas–liquid two-phase conditions. In addition, the turbulence of the flow field was enhanced with the increasing influent load; the swirling was remarkably reduced with the increase of gas holdup. Meanwhile, a thick micro-bubble filter layer was formed in the separation zone, which favored bubble-flocs agglomerating and rising. The force analysis also showed that the cross section within the tank contribute to the uniformity of the bottom water collection as well as enlargement of the bottom outflow area, therefore improving the overall flotation performance. The simulation results revealed for the CCDAF process can provide technical guidance for engineering design and application.

The water quality characteristics of Queshan reservoir (Jinan,China), which derived from Yellow River, were low temperature and low turbidity. Based on those characteristics, the flofilter, which joined flotation with filtration, was designed, and it has many advantages, such as less area, no flocculation tank, flexible operation, coordinated water purification of flotation and filtration, etc. Through the optimum study on flocculation conditions, PAFC was suited for Queshan reservoir water, and the optimum dosage of PAFC was 2.0 mg Al3+/L. In the conditions of low temperature and low turbidity, the filtration cycle was 72 hours, and the average removal efficiency of turbidity, CODMn, UV254, chroma were 86.49%, 43.46%, 63.51%, 75% respectively in the early running, and the flofilter showed higher water purification effect.

The water of Queshan reservoir (Jinan, China) which derived from Yellow River was treated by the technology of dual-media flofilter with GAC and sand, and the flocculation conditions, the flotation parameters and the filtration parameters were separatedly optimized. Based on the test result, PAFC was suited for Queshan reservoir water, and the optimum dosage was 2.0 mg A13+/L. HCl was added to adjust the pH of raw water, the influence of removal efficiency on turbidity was small, while the influence of removal efficiency on organic substance was comparatively large, and the influence result indicated: UV254 >; CODMn >; turbidity. The optimal value of dissolved air pressure was 0.30 MPa, and the optimal value of reflux ratio was 20% in the flotation unit. The filtration rate could not exceed 8m/h, and the filtration cycle was 3 days.