[Effects and Mechanism of the Combination of Ozone-PAC as a Pretreatment for the Reduction of Membrane Fouling].

The effects of ozone, powdered activated carbon (PAC), and their combination on controlling fouling and the removal of organic matter were investigated. The results showed that ozone mainly oxidized strong hydrophobic, high relative molecular mass () compounds and the high was transferred to medium and small hydrophilic fractions. Ozone could control fouling effectively, demonstrating that hydrophobic organic matter with higher contributed to membrane fouling.

[Influencing Factors of Assimilable Organic Carbon (AOC) Formation in Drinking Water During Ozonation Process].

The influences of ozone dosage, pH and ionic strength on the formation of Assimilable Organic Carbon (AOC) during ozonation were investigated. The result demonstrated that within the range of 1-5 mg · L⁻¹ O₃, the formation of AOC increased with increasing ozone dosage, but higher ozone dosage (9 mg · L⁻¹) resulted in reduction of AOC formation. AOC formation increased with higher pH but decreased with increasing ionic strength.

[Effects and mechanism on removing organics and reduction of membrane fouling using granular macro-porous anion exchange resin in drinking water treatment].

A granular macro-porous anion exchange resin combined with coagulation was used as pretreatment of microfiltration membrane, and their effects and mechanism on removing organics and reduction of membrane fouling were evaluated. The results showed that resin could be effective in removing organics with medium and small molecular weight ( Mr) but ineffective in removing organics with large Mr, while couagulation could significantly remove organics with large Mr, with a limited removal for organics with medium and small Mr. Using resin alone as pretreatment could be effective in removal of organics but limited in reduction of membrane fouling.

[DOM membrane fouling and effects on rejection behaviors of NF membranes].

This work investigated membrane fouling caused by two kinds of dissolved organic matters (DOMs), i. e., Qingcaosha (QCS) DOM and Taihu lake (TH) DOM, and the effects on the rejection behaviors of two different nanofiltration (NF) membranes, i.

[Effect of relative molecular mass distribution and hydrophilicity/ hydrophobicity of NOM on membrane fouling in MF-combined process].

This study investigated the reversible and irreversible foulants in a submerged microfiltration (MF) with pretreatments (coagulation/powdered activated carbon (PAC)/potassium permanganate) in a pilot scale treatment of water from Taihu Lake. The study focused on the effect of relative molecular mass (M(r)) distribution and hydrophilicity/hydrophobicity on membrane fouling using high performance size-exclusion chromatography (HPSEC) with UV and TOC detectors and three dimension fluorescence excitation-emission matrix (3DEEM). HPSEC analyses showed that pretreatments could almost completely remove the macro molecules (M(r) > 10 x 10(3)), but only eliminate part of medium (10 x 10(3)) > M(r) > 1 x 10(3)) and micro molecules (M(r) < 1 x 10(3)).

[Determination of the distribution of relative molecular mass of organic matter by high pressure size exclusion chromatography with UV and TOC detectors].

An on-line high pressure size exclusion chromatography (HPSEC) with UV and TOC detectors was adapted to examine the distribution of relative molecular mass of natural organic matter (NOM). Through synchronous determination of UV254 and TOC responses in a wide range of relative molecular mass, it was possible to accurately characterize the structure of NOM, especially for some non-aromatic and non-conjugated double bond organics which have low response to UV. It was found that, TOC detector was capable of detecting all kinds of organic matters, including sucrose, sodium alginate and other hydrophilic organic compounds.

[Researches on factors affecting the removal of carbamazepine by nanofiltration membranes].

The influence factors on removal of carbamazepine (CBZ) in drinking water by nanofiltration membrane was mainly investigated. The effect of CBZ removal by NF270 and NF90 was firstly compared and found that removal efficiency by NF90 with small pore size showed more effectively than removed by NF270 with large pore size. The next experiment focused on the effect of various factors on removal with respect to CBZ initial concentration, pH, ionic strength and water temperature.

[Effect of ozone/coagulation pretreatment on membrane fouling reduction].

In order to investigate the effect of ozone and coagulation pretreatments on organic matter and MF membrane filtration, pretreated Huangpu River surface water was filtrated by MF membrane. The results showed that there were the optimal dosages of ozone and coagulant made maximum membrane flux. The result of membrane fouling reduction by coagulation was better than that by ozone, which was relative to character of organic matter removed by two pretreatment processes.

[Characteristic of algogenic organic matter (AOM) membrane fouling and its effect on UF membrane fouling].

Algogenic organic matter (AOM) was extracted from blue-green algae (Cyanobacteria) and its characteristics was determined by various methods including high-pressure size-exclusion chromatography (HP-SEC), hydrophobic and hydrophilic fractionation and fluorescence excitation emission matrix (EEM). The results showed that AOM was composed of hydrophilic fraction predominantly, account for 78%. The SUVA of AOM was only 1.

Formation of chloroform during chlorination of alanine in drinking water.

Currently, dissolved nitrogenous organic matters in water, important precursors of disinfection by-products (DBPs), are of significant concern. This study was to explore the formation of chloroform (CF) during chlorination of alanine (Ala), an important nitrogenous organic compound commonly present in water sources. Our results indicated that the CF yield reached a maximum value of 0.

[Effect of preozonation on microfiltration for Huangpu River].

This study investigated the effect of preozonation on organic matter and microfiltration membrane filtration, Huangpu River surface water ozonated was filtrated by MF membrane. The results show that highest rejection efficiency of DOC and UVr by ozone are 10% and 71% respectively during 0.5-3.

[Degradation of MC-LR by combination of UV/H2O2 process].

The degradation of MC-LR in water by UV/H2O2 process was investigated. The effects of intensity of UV radiation, initial concentration of MC-LR, dosages of H2O2, initial pH value and anions on degradation of MC-LR by UV/H2O2 process were studied. The results show that the removal of MC-LR only by H2O2 is nearly zero, and UV process can degrade MC-LR to a certain extent.

[Effect of different organic fraction on membrane flux declines].

Organic matter in the tap water was isolated into strongly hydrophobic acids, weakly hydrophobic acids, charged hydrophilic and neutral hydrophilic by DAX-8, XAD-4 and IRA-958 synthetic resins. Filtration tests using polyvinylidene fluoride (PVDF), polyethersulphone (PES) and cellulose acetate (CA) membranes were conducted to investigate the contribution of different organic fractions to membrane fouling. The results show that in filtration of raw water, flux declines with PES, PVDF and CA membrane are 67%, 59% and 19% of the initial flux, indicating that the more hydrophobic membrane resulted in more severe fouling.

[Influence of coagulation pretreatment on UF membrane flux].

In this study, the effect of coagulation pretreatment on improvement of UF membrane filtration flux was investigated. The experiment using four water samples having different hydrophobic and hydrophilic compound was focused on the effect of coagulation on removing hydrophobic and hydrophilic fraction of organics and resulting enhanced flux. In the filtration of raw water, the organics removal for the four water samples were in the ranges of 12% and 20%, in which hydrophobic fraction accounting for over 50%, suggesting that membrane prefers to remove hydrophobic fraction.

Effect of coagulation pretreatment on the fouling of ultrafiltration membrane.

The purpose of this study is to understand the effect and mechanism of preventing membrane fouling, by coagulation pretreatment, in terms of fractional component and molecular weight of natural organic matter (NOM). A relatively higher molecular weight (MW) of hydrophobic compounds was responsible for a rapid decline in the ultrafiltration flux. Coagulation could effectively remove the hydrophobic organics, resulting in the increase of flux.

[Effect of chlorine on PAC's ability to adsorb microcystin].

Bottle-point experiments were conducted in Huangpu river raw water to examine the extent to which chlorine influenced the ability of powdered activated carbon (PAC) to adsorb two kinds of microcystins (MC-RR and MC-LR). The result shows that,when adding PAC and chlorine at the same point, chlorine can enhance the removal effect of the combined process (about 20%), which may be because the surface of PAC catalyzes the reaction between mirocystin and chlorine molecule, when adding PAC and chlorine at different points, the strengthening effect disappear [chlorine reduces the ability of PAC to microcystins to some extent (5%-10%)], the effect of chlorine to PAC becomes weak when raise the dosage of PAC. PAC can effectively remove microcystins (the removal effect can reach 55% and 45% for MC-RR and MC-LR respectively at the dosage of 10 mg/L, contact time of 6 hours) when using PAC alone.

[Removal of EDCs(BPA) by ultrafiltration and impact factors].

The removal of bisphenol A (BPA) in drinking water was investigated by ultrafiltration membranes (UF) using dead-end stirred-cell filtration system. The experiment was focused on the effect of various factors on removal efficiency with respect to BPA initial concentration, molecular weight cut offs (MWCOs) of membrane, pH, ionic strength and organic matter. The results showed that UF could remove BPA effectively.

[Effect of coagulation on preventing membrane from fouling].

In this experiment, the effects on improve of flux and prevention of membrane from fouling is studied. The results demonstrate that after backwashing, the flux was completely recovered by addition of 4mg/L and l0mg/L(as Al), while the flux was only 40% of initial flux without coagulation pretreatment. It is also observed that whether or not prevention of fouling by coagulation are depended on the characteristics of cake layer formed on membrane surface during membrane filtration.