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In recent years, the contribution of bacterial materials in water distribution systems to DBPs has attracted widespread attention from researchers. The risks and influencing factors of bacterial DBPs are reviewed. Factors affecting the generation of bacterial DBPs include the characteristics of bacterial materials, disinfection process, piping materials, and water quality. Among the major components of biofilms, proteins or amino acids have the greatest risk of DBPs. Among the commonly used disinfection methods, chlorine is more suitable for continuous disinfection of pipe networks than chloramine, but chlorine dioxide may be a better substitute in the future. Pipes with good biological stability, such as polyethylene (PE) pipe, should be encouraged to be used in water supply networks. Periodic removal of biofilms, reduction of organic matter and bromide ion concentrations, and maintenance of high flow rates are effective means to reduce bacterial DBPs. The control, removal and monitoring devices of tube wall biofilm need to be further developed and promoted. In the future, it is urgent to develop new disinfectants that are not easy to react with biomolecules and natural organic matter, and produce fewer or no by-products. HIGHLIGHTS Proteins or amino acids induce the greatest risk of DBP formation.; Chlorine is more suitable for continuous disinfection of pipe networks than chloramine, but chlorine dioxide may be a better substitute.; PE pipes should be encouraged to be used in water supply network.; The concentration of organic matter and bromide ions in the water should be reduced as much as possible and the high flow rate of the water should be maintained.;

Sublethally injured bacteria can still develop into normal bacteria under favorable growth conditions, and their pathogenicity poses a great threat to human health. In the drinking water system, some bacteria cause sublethal injury under the action of disinfectants, that is, disinfectant-injured bacteria. Hence, the detection of disinfectant-injured bacteria and the elucidation of injury mechanisms are of great significance for ensuring the microbial safety of drinking water systems. This article takes the indicator bacteria Escherichia coli as the research object, reviews and summarizes the sublethal injury conditions, damage mechanism, and detection methods of disinfectant-injured bacteria in drinking water, and puts forward a prospect for the future research directions of drinking water disinfection and disinfectant-injured bacteria. HIGHLIGHTS Sublethally injured bacteria are formed during the disinfection process.; Introduce the detection methods of disinfectant-injured bacteria.; The injury mechanisms of chlorine- and UV-injured bacteria are described.; It is recommended for an in-depth study of injury mechanisms, minimizing the potential harm of disinfectant-injured bacteria.;

Cryptosporidium and Giardia are globally recognized protozoa that directly cause human diarrhea. Their transmission route mainly involves drinking contaminated water, thus needing proper water treatment to avoid human infection. At present, there is a lack of review on the infection status and control measures of the two protozoa. Hence, this article summarizes and compares the infection status and the role of drinking water in transmitting the Cryptosporidium and Giardia in some key countries in Asia, Africa, Europe, and the Americas. With collected data, this review offers recommendations for sanitary control and provides theoretical support for the application of drinking water treatment projects. HIGHLIGHTS Need to strengthen preventive measures of Giardia and Cryptosporidium in animals.; Improve sanitation facilities, pay attention to non-core areas, and avoid concentrated outbreaks.; Reasonable selection of testing methods according to the needs and conditions of each country.; The water treatment process parameters need to be reasonably selected according to the natural water quality conditions.;

The antibacterial properties of tea polyphenols make them suitable for drinking water disinfection, but it is necessary to clarify the influence of metal ions on the sterilization efficacy. Epigallocatechin gallate (EGCG) was selected as a representative tea polyphenol, and the effects of calcium ion (Ca2+) concentration on its disinfection properties in Escherichia coli cultures were investigated. Changes in bacterial growth and structures were detected. The presence of low concentration Ca2+ (1–5 mM) inhibited the disinfection effect of EGCG but higher concentrations (6–10 mM) enhanced its effects. As Ca2+ concentration increased, the proportion of damaged bacteria also increased (15–43%). The presence of Ca2+ lessened the damaging effects of EGCG on the surface structures of E. coli but may have facilitated the entry of EGCG into the bacteria, enhancing its antibacterial efficacy. Tea polyphenols may be useful additives for the disinfection of groundwater and other raw waters containing calcium ions. HIGHLIGHTS Low concentration calcium ions inhibit the disinfection effect of EGCG, but high concentrations enhance disinfection.; Rate of EGCG-induced E. coli damage rises, as calcium ion concentration increases.; Calcium ions inhibit EGCG-induced damage to cell walls and membranes but promote internal structural damage.; Tea polyphenols may be useful for processing raw water with high calcium ion concentrations.;

Drought has caused serious damage to the water resource system and agricultural production in Shandong Province, China. This study calculated the standardized precipitation evapotranspiration index (SPEI) based on the monthly precipitation and average temperature data of 25 meteorological stations in Shandong Province from 1961 to 2017. The trend analysis method and ArcGIS software were utilized to analyze the multi-scale (SPEI-1, SPEI-3, and SPEI-12) spatiotemporal changes of drought. The results revealed that (1) The intensity of drought showed an increasing trend in Shandong Province from 1961 to 2017; (2) The main periods of the drought on the seasonal scale (spring, summer, autumn, and winter) and annual scale were 8 years, 4 years, 15 years, 4 years, and 4 years, respectively; (3) Of the four seasons, the frequency of drought in autumn and winter were the highest. At the annual scale, the high-frequency drought areas were mainly concentrated in the southern mountainous regions; (4) In terms of the spatial change trend of drought, Shandong Province as a whole displayed a trend of becoming wet in the central and southwest regions and dry in the eastern region; and (5) Droughts were discovered to be simultaneously influenced by multiple atmospheric circulation indices in Shandong Province. HIGHLIGHTS The intensity of drought showed an increasing trend.; The spatial distribution of drought in Shandong Province varies greatly at different scales.; The aridity trend across the entire province in autumn.; Droughts in Shandong Province were simultaneously affected by multiple atmospheric circulation indices.;

Calcined ternary hydrotalcite like compounds had been synthesized by co-precipitation and calcined at 450 °C for 6 h. It had been applied into the nitrate removal from aqueous solutions. Various factors during adsorption process, such as chemical composition of adsorbents, adsorbent dosage, initial concentration of nitrate, initial pH and co-existing anions on nitrate adsorption had been investigated. It was found that 1.5 g/L CHTlcs (Mg/Al/Fe molar ratio= 3:0.1:0.9) could achieve ideal adsorption efficiency at an initial nitrate concentration of 100 mg/L. The value of pH had little effect on nitrate adsorption. The co-existing anions had the inhibitory effect on nitrate adsorption, which was in the order of PO43- > SO42->Cl- > ClO4-. The batch adsorption studies showed that experimental data were well described by the pseudo-second-order kinetic model and Langmuir isotherm model, and the maximum isotherm adsorption capacity was 123.305 mg/g. The adsorption of nitrate was a spontaneous exothermic process with the reduction of entropy. The proposed adsorption mechanism obtained from characterization was that CHTlcs uptake nitrate through reconstruction effect and adsorption on external surface. [ABSTRACT FROM AUTHOR]

A electrocoagulation (EC)/peanut shell (PS) adsorption coupling technique was studied for the removal of malachite green (MG) in our present work. The addition of an appropriate PS dosage (5g/L)resulted in remarkable increase in the removal efficiency of MG at lower current density and shorter operating time compared with the conventional EC process. The effect of current density, pH of MG solution, dosage of PS and initial concentration of MG were also investigated. The maximum removal efficiency of MG was 98% under optimum conditions in 5 min. And it was 23% higher than that in EC process. Furthermore, the unit energy demand (UED) and the unit electrode material demand (UEMD)were calculated and discussed. The results demonstrated that the EC/PS adsorption coupling method achieved a reduction of 94% UED and UEMD compared with EC process. [ABSTRACT FROM AUTHOR]

The feasibility and performance of food waste and sewage sludge co-digestion were investigated to gain insight into their resource utilization. In this study, two-phase anaerobic digestion (TPAD) was operated under a total solids mixing ratio of 1:1 and different sludge retention times (SRTs). Results show that an acidogenic reactor with a 5-day SRT obtained the highest acidification efficiency, and its acetic acid content was dominant. The organic removal rate of a methanogenic reactor (MR) with a 20-day SRT and its corresponding TPAD system with a 25-day SRT were both the highest among the MRs and TPAD systems. Volatile solids and total chemical oxygen demand average removal efficiencies of the TPAD system with a 25-day SRT reached 64.7 and 60.8%, respectively. The MR with a 30-day SRT obtained the minimum ratio of volatile fatty acid to alkalinity (0.12). The methane content generated from the different MRs fluctuated at around 70%. All of the above results can provide reference for future research. [ABSTRACT FROM AUTHOR]

This paper, taking Chagan lake as the study area, uses and improves MWR V1.0 (Rivers (Lake) Health Assessment Indicators, Standards and Methods V1.0) relating to the theory and method of physical structure integrity assessment. A 500 m× 1000 m grid on the lakeshore zone is a basic evaluation unit, and then a lakeshore physical structural integrity evaluation system using remote sensing (RS) and geographic information system (GIS) technology is established, which contains a target layer, criterion layer and indicator layer. The criterion layer consists of lakeshore condition, shoreline development rate and lake atrophy rate, and the index layer is composed of slope, vegetation cover rate and water level change rate, and another eight indicators. The results showed that for the 23 monitoring points in Chagan lake and the 15 monitoring points in Xinmiao lake, the evaluation results based on RS were 0.60-0.74 and 0.35-0.52, respectively, and the field evaluation results were 0.64- 0.77 and 0.35-0.55, respectively. The evaluation results of the two methods consistently indicated that the physical structure of the lakeshore of Chagan lake was healthy and the Xinmiao's lakeshore was sub-health. On this basis, a piecewise evaluation method of physical structure integrity based on the division of the nature reserve function was proposed in this paper. [ABSTRACT FROM AUTHOR]

Anaerobic digestion of waste activated sludge was conducted to gain insight into the mechanisms underlying change in sludge dewaterability during its anaerobic digestion. Unexpectedly, the results indicated that sludge dewatering properties measured by capillary suction time only deteriorated after 10 days of anaerobic digestion, after which dewaterability recovered and remained stable. The loosely bound extracellular polymeric substance (LB-EPS) content increased three-fold after 20 days of anaerobic digestion, and did not change significantly during the remaining 30 days. The tightly bound EPS (TB-EPS) content reduced slightly after 20 days of anaerobic digestion, and stabilized during the last 30 days. Polysaccharides (PS) and proteins (PN) content in LB-EPS increased after 10 days of anaerobic digestion. However, PS and PN contents in TB-EPS decreased slightly. The relationship analysis showed that only LB-EPS correlated with dewaterability of the sludge during anaerobic digestion. [ABSTRACT FROM AUTHOR]

Microbial fuel cells (MFCs) are devices that exploit microorganisms as biocatalysts to degrade organic matter or sludge present in wastewater (WW), and thereby generate electricity. We developed a simple, low-cost single-chamber microbial fuel cell (SCMFC)-type biochemical oxygen demand (BOD) sensor using carbon felt (anode) and activated sludge, and demonstrated its feasibility in the construction of a real-time BOD measurement system. Further, the effects of anodic pH and organic concentration on SCMFC performance were examined, and the correlation between BOD concentration and its response time was analyzed. Our results demonstrated that the SCMFC exhibited a stable voltage after 132 min following the addition of synthetic WW (BOD concentration: 200 mg/L). Notably, the response signal increased with an increase in BOD concentration (range: 5-200 mg/L) and was found to be directly proportional to the substrate concentration. However, at higher BOD concentrations (>120 mg/L) the response signal remained unaltered. Furthermore, we optimized the SCMFC using synthetic WW, and tested it with real WW. Upon feeding real WW, the BOD values exhibited a standard deviation from 2.08 to 8.3% when compared to the standard BOD5 method, thus demonstrating the practical applicability of the developed system to real treatment effluents. [ABSTRACT FROM AUTHOR]

In order to improve the sonocatalytic activity of TiO2, Al2O3/TiO2, Y2O3/TiO2 and Fe2O3/TiO2 composites were prepared using mechanical mixing, liquid boiling, ultrasonic dispersion and heat-treated methods. And then, a series of degradation experiments were carried out under ultrasonic irradiation. Also, the influences of heat-treated temperature and heat-treated time on the sonocatalytic activity of Al2O3/TiO2, Y2O3/TiO2 and Fe2O3/TiO2, and ultrasonic irradiation time and solution acidity on the sonocatalytic degradation of Acid red B were investigated by UV-vis spectra. It was found that the degradation ratio showed significant increase in the order TiO2 < Fe2O3/TiO2 < Y2O3/TiO2 < Al2O3/TiO2. And the corresponding percentage degradations are about 37, 45, 52 and 81%, respectively. In addition, for exploring the universality, the degradation of other several organic dyes was also reviewed under the same conditions. Because of good degradation efficiency, this method may be an advisable choice for the treatment of non- or low-transparent wastewaters in the future. [ABSTRACT FROM AUTHOR]

In this work, an upconversion luminescence agent, crystallized Er3+:YAlO3, was synthesized and then coated by the nano-sized TiO2 film through sol-gel technique. A novel TiO2 photocatalyst, Er3+:YAlO3/TiO2, with high activity in visible light was subsequently prepared. The Er3+:YAlO3 and Er3+:YAlO3/TiO2 were characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The photocatalytic activity of Er3+:YAlO3/TiO2 photocatalyst was tested by the degradation of acid red B in aqueous solution as the primary model compound under visible light irradiation. The experimental results proved that the prepared TiO2-coated crystallized Er3+:YAlO3 was able to decompose the acid red B efficiently, and it is promising to use the idea to develop new TiO2 photocatalyst with high activity for photocatalytic degradation under visible light. [ABSTRACT FROM AUTHOR]