The performance of biological and tertiary wastewater treatment procedures for rotaviruses A removal

Environmental Science and Pollution Research - Enteric viruses, generally found in sewage, are recognized as the main cause of waterborne and foodborne public health outbreaks. Among leading...     

Adsorption and breakdown of penicillin antibiotic in the presence of titanium oxide nanoparticles in water

The fate and transport of antibiotics in natural water systems is controlled in part by interactions with nanometer (10⁻⁹ m) metal oxide particles. Experiments were performed by mixing solutions of ampicillin (AMP), a common, penicillin-class human and veterinary antibiotic, with 25 nm-TiO₂ (anatase) nanoparticles at different pH conditions. Both sorption and degradation of AMP were observed in the AMP-nanoparticle solutions. For AMP concentrations from ∼3 μM to 2.9 mM the overall AMP removal from solution can be described by linear isotherms with removal coefficients (K_r) of 3028 (±267) L kg⁻¹ at pH 2, 11,533 (±823) L kg⁻¹ at pH 4, 12,712 (±672) L kg⁻¹ at pH 6, and 1941 (±342) L kg⁻¹ at pH 8. Mass spectral analysis of AMP solutions after removal of the solid nanoparticles yielded ions that indicate the presence of peniclloic acid, penilloic acid and related de-ammoniated by-products as possible compounds resulting from the degradation of AMP at the TiO₂ surface.     

Hydrous ferric oxide nanoparticles hosted porous polyethersulfone adsorptive membrane: chromium (VI) adsorptive studies and its applicability for water/wastewater treatment

In this present study, adsorptive membranes for Cr(VI) ion removal were prepared by blending polyethersulfone (PES) with hydrous ferric oxide (HFO) nanoparticles (NPs). The effects of HFO NPs to PES weight ratio (0–1.5) on the physicochemical properties of the resultant HFO/PES adsorptive membranes were investigated with respect to the surface chemistry and roughness as well as structural morphologies using different analytical instruments. The adsorptive performance of the HFO NPs/PES membranes was studied via batch adsorption experiments under various conditions by varying solution pH, initial concentration of Cr(VI), and contact time. The results showed that the membrane made of HFO/PES at a weight ratio of 1.0 exhibited the highest adsorption capacity which is 13.5 mg/g. Isotherm and kinetic studies revealed that the mechanism is best fitted to the Langmuir model and pseudo-second-order model. For filtration of Cr(VI), the best promising membranes showed improved water flux (629.3 L/m² h) with Cr(VI) ion removal of 75%. More importantly, the newly developed membrane maintained the Cr(VI) concentration below the maximum contamination level (MCL) for up to 9 h.

     

Investigation of the role of biopolymer clusters in MBR membrane fouling using flash freezing and environmental scanning electron microscopy

The technique that employs flash freezing and environmental scanning electron microscopy (ESEM) was utilised for detailed investigation of the fouling materials in a membrane bioreactor (MBR). The method involves the flash freezing of a wet sample in liquid nitrogen for 10 s to preserve its structure for direct ESEM observation with a high image resolution. ESEM images show that the sludge cake formed by simple filtration of the MBR bulk sludge has a highly porous, sponge-like structure with a fairly low resistance. However, the fouling layer attached to the membrane surface contains a thin gel layer under the main body of the sponge-like sludge cake, which is similar to that formed by filtration of a dispersion of biopolymer clusters (BPCs). It is apparent that BPCs tend to accumulate on the membrane surface, and the gel layer is largely responsible for the high filtration resistance of the cake layer on the fouled membranes.     

The use of XAD-resins for the detection of mutagenic activity in water: I. Studies with surface water

A study of the effects of different XAD-resins, bed volume, flow rate, pH and type of eluent on the extraction of organic mutagens from surface water is presented. XAD-4/8 is as effective as XAD-2 in concentrating organic mutagens from surface water and dimethylsulfoxide (DMSO) is as efficient as acetone in eluting the adsorbed organic mutagens. The latter allows direct testing up to 0.5 ml of DMSO concentrate in the Ames test. Variation of the pH of the water after passing the XAD-4/8, followed by readsorption, shows that the majority of the mutagenic activity due to dissolved organics is adsorbed at neutral pH. Only a minor fraction is readsorbed at pH 3. Further a XAD-4/8 concentrate and a similar concentrate prepared by freeze drying gives similar mutagenic activity. This indicates that many of the organic mutagens are recovered in the XAD-4/8 concentrate.It is concluded that adsorption on XAD-4/8, followed by direct testing of the DMSO eluates in the Ames test, presents a rapid and relatively simple way to detect low concentrations of organic mutagens in surface water. The general suitability of the method is shown for different types of surface water.     

Influencing factors and improvement paths of green water use efficiency in the Yellow River Basin: a new perspective based on ecogeographical divisions

Environmental Science and Pollution Research - Exploring the influencing factors and improvement paths of green water use efficiency (GWUE) based on different regions is very important for the...     

活性污泥中EPS的2种测定方法及其对膜通量的影响

以动态膜生物反应器（DMBR）中养殖废水为研究体系,探讨活性污泥中细菌胞外多聚物（EPS）的2种测定方法,蛋白质多糖加合法（EPS PSP）、TOC法（EPS TOC）及其与膜通量之间的相关性研究。结果表明,EPS PSP与EPS TOC的相关性较好,相关系数R2为0.9183;EPS PSP约为EPS TOC的80%左右。EPS TOC和EPS PSP与膜通量的相关系数较低,仅为0.490和0.412,说明造成膜污染的因素很多,相比之下,EPS TOC比EPS PSP更适合说明膜生物反应器中的污泥状态,更能体现膜污染的状况。     

The fate and importance of organics in drinking water treatment: a review

In the pioneer days, the main driving forces for research of organics in drinking water treatment (DWT) were human health risks and optimisation of technology. The focus was on natural organic matter (NOM) structure, disinfection by-products (DBPs) formation, NOM removal by means of coagulation, adsorption, and oxidation, and development of the most efficient water treatment trains. Surprisingly, after decades of research, rapid development of analytical techniques and progress in risk assessment, the same driving forces are still in the limelight — although the topics have changed slightly. The attention switched from trihalomethanes to a new generation of DBPs. The definition of hydrophilic/hydrophobic NOM depends on the technique used for characterisation. It has become evident that numerous organic compounds can threaten water supply sources. Some of them had been ignored or overlooked in the past, but have recently been detected by advanced analytical tools even in drinking water. Prioritisation becomes priority per se. As far as processes are concerned, mainstream research has been following three lines: fouling mechanisms, application of hybrid processes and interactions between synthetic organic chemicals, other water constituents and materials used in DWT. Significant development has been made in membrane technology. This paper presents a broad overview of the recent organics research. Although the state-of-the-art technologies seem to have an answer to each and every question raised, it is still necessary to deal with specific problems on a case-by-case basis mainly due to the unique nature of NOM and different xenobiotics that may appear in various types of waters. In the end, human health risk, which derives from the presence/absence of organics, is only the tip of the iceberg — underneath lies a whole new universe — the socio-economic aspect of water treatment and quality that deserves much more attention.     

盐度对序批式反应器与间歇曝气膜生物反应器污水处理效果的影响

采用序批式反应器(SBR)与间歇曝气膜生物反应器(IAMBR)处理模拟生活污水,考察了进水盐度对两反应器污水处理效果的影响。研究表明,当进水盐度为0g/L(以NaCl质量浓度计,下同)时,SBR和IAMBR对总有机碳(TOC)、NH4+-N及TN的去除能力相当,IAMBR未表现出明显的优势;当进水盐度为10g/L时,SBR和IAMBR对TOC、NH4+-N及TN的去除产生明显的差异。IAMBR因为膜的截留与微生物富集作用,对污染物的去除无明显变化,依然保持了较高的污染物去除率,而SBR受盐度冲击影响较大,TOC、NH4+-N及TN的去除率均大幅降低,说明IAMBR具有较高的抗盐度冲击性能。     

Chitosan/albumin/CaCO3 as mimics for membrane bioreactor fouling: genesis of structural mineralized-EPS-building blocks and cake layer compressibility

Membrane bioreactor biofouling is usually described as an extracellular matrix in which biopolymers, inorganic salts and active microbes co-exist. For that reason, biomineralization (BM) models can be useful to describe the spatial organization and environmental constraints within the referred scenario. BM arguments were utilized as background in order to (1) evaluate CaCO₃ influence on flux decline; pore blocking and cake layer properties (resistance, permeability and compressibility) in a wide range of Chitosan/Bovine serum albumin (BSA) mixtures during step-pressure runs and, (2) perform membrane autopsies in order to explore the genesis of mineralized extracellular building blocks (MEBB) during cake layer build up. Using low molecular weight chitosan (LC) and BSA, 2 L of 5 LC/BSA mixtures (0.25-1.85 ratio) were pumped to an external ultra filtration (UF) membrane (23.5 cm², hydrophobic, piezoelectric, 100 kDa as molecular weight cut-off). Eight different pressure steps (40 ± 7 to 540 ± 21 kPa) were applied. Each pressure step was held for 900 s. CaCO₃ was added to LC/BSA mixtures at 0.5, 1.5 and 3 mM in order to create MEBB during the filtration tests. Membrane autopsies were performed after the filtration tests using thermo gravimetric, scanning microscopy and specific membrane mass (mg cm⁻²) analyses. Biopolymer-CaCO₃ step-pressure filtration created compressible cake layers (with inner voids). The formation of an internal skeleton of MEBB may contribute to irreversible fouling consolidation. A hypothesis for MEBB genesis and development was set forth.     

Combined biological and photocatalytic treatment for the mineralization of phenol in water

Phenol is degraded by biological treatment, however mineralization requires long time. To decrease the time and operational cost necessary for the mineralization of phenol, an optimum operation condition of the combined biological–photocatalytical treatment was investigated. The mineralization of phenol (50 mg l⁻¹) was conducted in a flow-type biomembrane tank combined with a batch-type TiO₂-suspended photocatalytic reactor. Phenol was degraded biologically to the concentration of 6.8 mg l⁻¹, an effective concentration for further photocatalytic treatment. After the biological treatment, the biotreated phenol was treated photocatalytically to complete the mineralization of phenol. The combined treatment shortened the mineralization time compared to the biological treatment and electric cost compared to the photocatalytic treatment only. The combined treatment may be suitable for a short-time mineralization of phenol in wastewater.     

The use of food waste-based diets and Napier grass to culture grass carp: growth performance and contaminants contained in cultured fish

The present study used commercial feeds, food waste feeds, Napier grass, and mixed feeds (food waste feed to Napier grass ratio, 1:10) to feed grass carp (Ctenopharyngodon idellus). The results indicated that grass carp fed with food waste feeds and mix feeds achieved growth performance (based on specific growth rate and feed conversion ratio) that was similar to commercial feeds (p?>?0.05). Concentrations of metalloid/metals in food waste feeds and polycyclic aromatic hydrocarbons (PAHs) in Napier grass were relatively higher than other types of fish feeds (p?<?0.05). However, most of the metalloid/metals and PAH levels in fish fed with four types of fish feeds were not significantly different (p?>?0.05). These findings show that food waste feeds are suitable for using in the production of fish feed and Napier grass can be served as supplemental feeds for grass carp, and hence reducing the production cost.     

Photodecomposition of humic acid and natural organic matter in swamp water using a TiO2-coated ceramic foam filter: Potential for the formation of disinfection byproducts

This paper reports on the photodecomposition of aqueous humic acid (HA) by a TiO₂-coated ceramic foam filter (TCF) reactor and on the potential for the formation of disinfection byproducts (DBPs) upon chlorination of the photocatalytically treated solutions. This photocatalytic reactor can also be applied to the removal of natural organic matter (NOM) in swamp waters. The proposed photocatalytic reaction system was operated as per standardized methodologies. First, the ability of the TCF to decompose HA (a representative compound of NOM) was evaluated from the changes in the total organic carbon (TOC) and UV₂₅₄ with the reaction time. Remarkably, TOC removal and UV₂₅₄ values ranging from 44% to 61% and from 60% to 83%, respectively, were achieved. The potential for the formation of DBPs (total trihalomethane and total haloacetic acid) by chlorination of the phototreated solution was strongly dependent on the TOC removal and UV₂₅₄ values in the solution. The degree of photodecomposition of NOMs in the swamp water samples and the DBP formation potential showed similar trends as in the case of the standard solutions containing HA. The method used in this study could be effectively used to evaluate the efficiency of TCF for reducing HA and NOM, while suppressing the formation of DBP products.     

Application of molecularly imprinted and non-imprinted polymers for removal of emerging contaminants in water and wastewater treatment: a review

Over the past decade, several studies have reported trace levels of endocrine disrupting compounds, pharmaceuticals, and personal care products in surface waters, drinking water, and wastewater effluents. There has also been an increased concern about the ecological and human health impact of these contaminants, and their removal from water and wastewater has become a priority. Traditional treatment processes are limited in their ability to remove emerging contaminants from water, and there is a need for new technologies that are effective and feasible. This paper presents a review on recent research results on molecularly imprinted (MIP) and non-imprinted (NIP) polymers and evaluates their potential as a treatment method for the removal of emerging contaminants from water and wastewater. It also discusses the relative benefits and limitations of using MIP or NIP for water and wastewater treatment. MIP, and in particular NIP, offer promising applications for wastewater treatment, but their toxicity and possible health effects should be carefully studied before they are considered for drinking water treatment. More research is also required to determine how best to incorporate MIP and NIP in treatment plants.     

Status of water use and potential of rainwater harvesting for replacing centralized supply system in remote mountainous areas: a case study

Environmental Science and Pollution Research - The failure of the centralized water supply system forced XY community to become more dependent on uncertain and unstable water sources. The results...     

Sulfur-oxidizing autotrophic and mixotrophic denitrification processes for drinking water treatment: elimination of excess sulfate production and alkalinity requirement

The activity of copper oxide, titanium carbide and silicon nitride nanoparticles for the oxidative degradation of environmentally relevant concentrations (μg L⁻¹ range) of enrofloxacin - an important veterinary antibiotic drug - in aqueous solutions was investigated. With hydrogen peroxide as an oxidative agent, both copper oxide and titanium carbide decrease the concentration of enrofloxacin by more than 90% over 12 h. Addition of sodium halide salts strongly increases the reaction rate of copper oxide nanoparticles. The mechanism for the formation of Reactive Oxygen Species (ROS) was investigated by Electron Spin Resonance (ESR).     

Review on the use of enzymes for the detection of organochlorine, organophosphate and carbamate pesticides in the environment

Pesticides are released intentionally into the environment and, through various processes, contaminate the environment. Three of the main classes of pesticides that pose a serious problem are organochlorines, organophosphates and carbamates. While pesticides are associated with many health effects, there is a lack of monitoring data on these contaminants. Traditional chromatographic methods are effective for the analysis of pesticides in the environment, but have limitations and prevent adequate monitoring. Enzymatic methods have been promoted for many years as an alternative method of detection of these pesticides. The main enzymes that have been utilised in this regard have been acetylcholinesterase, butyrylcholinesterase, alkaline phosphatase, organophosphorus hydrolase and tyrosinase. The enzymatic methods are based on the activation or inhibition of the enzyme by a pesticide which is proportional to the concentration of the pesticide. Research on enzymatic methods of detection, as well as some of the problems and challenges associated with these methods, is extensively discussed in this review. These methods can serve as a tool for screening large samples which can be followed up with the more traditional chromatographic methods of analysis.     

Large-scale utilization of water hyacinth for nutrient removal in Lake Dianchi in China: The effects on the water quality, macrozoobenthos and zooplankton

An ecological engineering project using water hyacinth for nutrient removal was performed in Baishan Bay of a large shallow eutrophic lake, Lake Dianchi in China. In the present study, a systematic survey of water quality, macrozoobenthos and zooplankton inside (IWH), around (AWH) and far away (FWH) water hyacinth mats was conducted in Baishan Bay from August to October 2010. The results showed that the water quality significantly improved at AWH area. Concentrations of nitrogen and phosphorus were lower and transparency was higher at AWH area than those in IWH and FWH areas. Total densities, dominant species densities, and biodiversity indexes of macrozoobenthos and cladocerans as well as copepods did not differ (P > 0.05) among each other in all three areas. It was significantly (P < 0.05) different for those of rotifers at IWH area compared to those in AWH and FWH areas. The results might suggest a tremendous potential for the utilization of water hyacinth in the eutrophic lake like Lake Dianchi for nutrients removal.     

Bromide levels in natural waters: its relationship to levels of both chloride and total dissolved solids and the implications for water treatment

South Australian freshwaters from a wide variety of environments were analysed for bromide and the results correlated with both chloride and total dissolved solids (TDS) concentrations. A linear relationship was obtained which allows chloride data to be successfully used to estimate bromide concentrations. Bromide displayed a slightly better correlation with TDS indicating that an improved estimate of bromide could be made by reference to TDS data which is more easily and commonly obtained, and generally available extensively as historical data. The bromide content in relation to its ratio with both chloride and TDS contents was around seventy percent of the corresponding ratios found in seawater, a finding reported in other published data. The ability to estimate bromide concentrations is a potentially useful tool in the drinking water industry as it enables the assessment of the extent of bromate formation (predicted through the use of mathematical models and other water quality data) which is an important factor when ozonation is being considered as a treatment option, particularly as many water industry regulatory bodies have imposed stringent limits on the levels of acceptable bromate.     

Inactivation of Bacillus subtilis spores during ozonation in water treatment plant: influence of pre-treatment and consequences for positioning of the ozonation step

This study reports on quantitative methodology for rational selection of the ozone injection point within unit processes of conventional drinking water treatment plants to improve disinfection efficiencies. The method is based on the fact that a specific inactivation level of microorganisms is achieved at a unique value of ozone exposures, independent of ozone dose and type of water, and quantitatively described by a Delayed Chick-Watson model (C T(lag): 1.03mgl(-1), k: 1.44mg(-1)lmin(-1)). This study demonstrated this phenomenon by performing the inactivation of Bacillus subtilis (B. subtilis) spores with ozone in various types of water collected from a series of unit processes in a water treatment plant. Simple measurements of the ozone decomposition behavior in waters from each unit process of a water treatment plant can allow the quantitative evaluation of the ozone needed to achieve a required level of inactivation. This methodology will be useful for drinking water treatment plants which intend to improve the disinfection efficiencies of their ozonation process.