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To improve the adsorption efficiency of layered double hydroxides (LDHs) for heavy metals, a novel sodium alginate (SA) intercalated MgAl-LDH (SA-LDH) was synthesized in this work. SA-LDH was characterized by XRD, FTIR, XPS and employed as adsorbent for Cd(II), Pb(II), Cu(II) elimination. Adsorbent dosage, initial pH and contact time, which are regarded as several key parameters, were optimized. The results showed that SA-LDH exhibited better adsorption performance compared with the pristine MgAl-LDH. The maximum adsorption capacities of SA-LDH for Cu(II), Pb(II) and Cd(II) reached 0.945, 1.176 and 0.850 mmol/g, respectively. The possible mechanisms were analyzed by XPS, XRD and FTIR. The results showed that Cd(II), Pb(II) and Cu(II) may be removed by SA-LDH via (i) bonding or complexation with Sur-OH or Sur-O- of SA-LDH, (ii) precipitation of metal hydroxides or carbonates, (iii) isomorphic substitution, and (iv) chelation with −COO− in the interlayers. This work provides an effective method for the development of LDH-based adsorbent and the treatment of wastewater containing heavy metals.

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.

Seasonal cyanobacterial blooms in eutrophic water releases algal organic matter (AOM), which contains large amount of dissolved organic nitrogen (DON) and is difficult to be removed effectively by conventional treatment processes (e.g., coagulation and sand filtration) because of its high hydrophilicity. Moreover, N-nitrosodimethylamine (NDMA) can be generated by the reaction of AOM with disinfectants in the subsequent disinfection process. In this study, the formation of NDMA from different AOM components was explored and the control of algal-derived NDMA precursors by UV/H2O2/O3 was evaluated. The results showed that the hydrophilic and polar components of AOM with the low molecular weight had higher NDMA yields. UV-based advanced oxidation process (AOPs) is effective in degrading NDMA precursors, while the removal rate can be affected greatly by UV doses. The removal rate of NDMA precursors by UV/H2O2/O3 is higher than by UV/H2O2 or UV/O3 which can reach 95% at the UV dose of 400 mJ/cm2. An alkaline environment reduces the oxidation efficiency of UV/H2O2/O3 technology, while an acidic environment is conducive to its function. Inorganic anions such as HCO3-, SO42-, Cl- and NO3- are potential to compete with target algal-derived NDMA precursors for the oxidants reaction and inhibit the degradation/removal of these precursors. The degradation of algal-derived NDMA precursors by UV/H2O2/O3 is mainly accomplished by the oxidation of DON with secondary amide groups, and the main degradation mechanism by UV/H2O2/O3 was through the initial decomposition of macromolecular organic compounds such as biopolymers and humic substances and the further degradation of resulting small molecular components.

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...

The quality of raw water and the current high level of pollution presents a phenomenon of high hardness and micropollution. An experimental study was conducted of the nanofiltration (NF) pilot-scale process combined with biological contact oxidation precipitation and ultrafiltration (UF) as the pretreatment process to treat this water. The study investigated the removal efficiency and membrane fouling of the NF process under the continuous and stable operating conditions of the combination process and studied the influence of high-hardness water on the membrane pollution of the combination process. The results showed that the combined process had a positive removal effect on conventional pollutants and characteristic pollutants, and the removal rates of conventional pollutants, such as turbidity, UV254 and CODMn, were 95%, 90% and 85%, respectively. The removal efficiency of total hardness, total alkalinity and soluble total solids reached 98%, 86% and 91%, respectively, and that of total desalination was above 95%. The removal rates of fluorescent organic substances, such as tryptophan, tyrosine, soluble microbial products (SMPs), fulvic acid and humus-like substances, as well as the precursors of disinfection byproducts reached over 88% and 50%, respectively. The pollutant removal efficiency of the combined process was mainly concentrated in the NF unit. The pretreatment process had certain removal effects on turbidity and macromolecular organic substances in the raw water, which provided a perfect operating environment for the NF process. Under long-term operation, the main elements of scaling on the surface of the NF membrane included C, O, Na, Mg, Al, Si, S, Cl, Ca, Ti and Fe, which were mainly concentrated at the outlet of the membrane and mainly came from monomers or compounds composed of inorganic salts in the raw water and some organic compounds. High-hardness water accelerated the change in membrane process parameters, and the surface of the membrane had abundant inorganic scaling. The inorganic scale on the surface of the NF membrane increased noticeably when filtering water with high hardness. Regular cleaning of the UF and NF membranes could effectively restore the parameters of the process and prolong the service life of the membrane process.

In this paper, the pollution of chlorinated hydrocarbons in the groundwater system is taken as the main research object. According to the adsorption characteristics of chlorinated hydrocarbons in different aquifer media, carbon tetrachloride is taken as an example to carry out isothermal adsorption experiments under different solid medium conditions. The concentration data are obtained by fitting the standard curves of linear, Langmuir, Freundlich, and Temkin types to study the mechanism of chlorinated hydrocarbons in different media. The results show that the adsorption capacity of silty clay is greater than that of limestone at the same initial concentration. Therefore, before the pollutants enter the karst water, the silty clay will “intercept” the pollutants. However, once the karst water is polluted, the limestone medium has a small adsorption capacity, which will bring difficulties to pollution control and treatment.

In this paper, water from the Yellow River reservoir was treated with Polyaluminum chloride (PAC) and a PAC/chitosan (CTS) composite to study the flocculation efficiency, changes in the flocculation characteristics, and the role played by CTS in the process of coagulation. The floc microstructure was analyzed by scanning electron microscopy, and the floc characteristics and fractal dimension were studied using a laser particle size analyzer. The results showed that addition of a small quantity of CTS could produce a relatively good coagulation effect, and the removal effect of each index increased by 8.7 %–46.83 % compared with that obtained with only PAC. However, as the dose increased, the effects on various indexes did not increase significantly. Under the same conditions, the growth rate and size of flocs formed with the composite coagulant containing CTS were better than those obtained with only PAC, with an increase in the floc size about 36.67 % with CTS. The floc regeneration capacity showed the opposite trend. It is likely that when long-chain bridging is dominant, the conditions are more conducive to rapid formation of structured and dense flocs. By contrast, when electrical neutralization plays a leading role, the flocs have better disintegration and regeneration abilities.

Carbon tetrachloride (CCl4) is a kind of toxic and persistent groundwater contaminant. Considering keeping drinking water safe, a novel kind of N-doped graphene (NGS)-P25 TiO2 photocatalyst was prepared by a facile one-step hydrothermal method for the removal of CCl4 from contaminated water. Simultaneously, nitrogen-doping and the reduction of graphene oxide, and loading of P25 were finished during the same process. The photocatalytic efficiency of resulted NGS-P25 nanoparticles was studied for the degradation of CCl4. The results indicated that NGS-P25 exhibited the highest photocatalytic activity under UV light irradiation, outperforming graphene-P25, bare P25 or NGS. The effects of NGS-P25 dosage, irradiation time, CCl4 concentration and pH on CCl4 photocatalytic degradation efficiency were discussed in detail. Accordingly, the optimum experimental conditions were obtained. Moreover, the high performance photocatalyst of NGS-P25 can be extended to environmental pollution control and remediation towards various pollutants.

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.

TEM investigation was performed to analyze the characteristics of the cell breakage of cyanobacterium ( M.aeruginosa) after being oxidized by Cl2, CIO2 and O3 respectively, and the mechanism of intracellular microcystins releasing and the removal effectiveness by different chemical oxidants was further discussed. The results show that all the three oxidants can cause decomposing of cyanobacterum cells and even cause intracellular microcystins releasing, while O3 has the most serious effect. Under the low dosage (0.5 mg/L) of oxidants, the quantity of the release of intracellular microcystins caused by ClO2 is most remarkable, and the intracellular microcystins removal by O3 proves better than that by Cl2 and ClO2. Considering the safety factor of the intracellular microcystins removal, 03 should be given the priority when choosing chemical oxidant while Cl2 is not recommended to remove cyanobacteriaum microcystins in the drinking water treatment.