Yonghui Song

The remediation of heavy metals contaminated sediment

Heavy metal contamination has become a worldwide problem through disturbing the normal functions of rivers and lakes. Sediment, as the largest storage and resources of heavy metal, plays a rather important role in metal transformations. This paper provides a review on the geochemical forms, affecting factors and remediation technologies of heavy metal in sediment. The in situ remediation of sediment aims at increasing the stabilization of some metals such as the mobile and the exchangeable fractions; whereas, the ex situ remediation mainly aims at removing those potentially mobile metals, such as the Mn-oxides and the organic matter (OM) fraction. The pH and OM can directly change metals distribution in sediment; however oxidation-reduction potential (ORP), mainly through changing the pH values, indirectly alters metals distribution. Mainly ascribed to their simple operation mode, low costs and fast remediation effects, in situ remediation technologies, especially being fit for slight pollution sediment, are applied widely. However, for avoiding metal secondary pollution from sediment release, ex situ remediation should be the hot point in future research.

Nutrients removal and recovery from anaerobically digested swine wastewater by struvite crystallization without chemical additions

Anaerobically digested swine wastewater contains high concentrations of phosphorus (P) and nitrogen (N). A pilot-scale experiment was carried out for nutrients removal and recovery from anaerobically digested swine wastewater by struvite crystallization. In the pilot plant, a sequencing batch reactor (SBR) and a continuous-flow reactor with struvite accumulation devices were designed and employed. The wastewater pH value was increased by CO(2) stripping, and the struvite crystallization process was performed without alkali and Mg(2+) additions. Results of the long-term operation of the system showed that, both reactors provided up to 85% P removal and recovery over wide ranges of aeration times (1.0-4.0 h), hydraulic retention times (HRT) (6.0-15.0 h) and temperatures (0-29.5°C) for an extended period of 247 d, in which approximate 30% of P was recovered by the struvite accumulation devices. However, 40-90% of NH(4)(+)-N removed was through air stripping instead of being immobilized in the recovered solids. The recovered products were detected and analyzed by scanning electron microscope (SEM), X-ray diffraction (XRD) and chemical methods, which were proved to be struvite with purity of more than 90%. This work demonstrated the feasibility and effects of nutrients removal and recovery from anaerobically digested swine wastewater by struvite crystallization without chemical additions.

Combination of upflow anaerobic sludge blanket (UASB) and membrane bioreactor (MBR) for berberine reduction from wastewater and the effects of berberine on bacterial community dynamics.

Berberine is a broad-spectrum antibiotic extensively used in personal medication. The production of berberine results in the generation of wastewater containing concentrated residual berberine. However, few related studies up to date focus on berberine removal from wastewaters. In this study, a lab-scale upflow anaerobic sludge blanket (UASB)-membrane bioreactor (MBR) process was developed for berberine removal from synthetic wastewater. The performance of the UASB-MBR system on berberine, COD and NH(4)(+)--N removal was investigated at different berberine loadings. And the effects of berberine on bacterial communities were evaluated using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). Results showed that, as the increase of berberine loadings, UASB performance was affected remarkably, whereas, efficient and stable performance of MBR ensured the overall removal rates of berberine, COD and NH(4)(+)--N consistently reached up to 99%, 98% and 98%, respectively. Significant shifts of bacterial community structures were detected in both UASB and MBR, especially in the initial operations. Along with the increase of berberine loadings, high antibiotic resisting species and some functional species, i.e. Acinetobacter sp., Clostridium sp., Propionibacterium sp., and Sphingomonas sp. in UASB, as well as Sphingomonas sp., Methylocystis sp., Hydrogenophaga sp. and Flavobacterium sp. in MBR were enriched in succession.

Applying fluorescence spectroscopy and multivariable analysis to characterize structural composition of dissolved organic matter and its correlation with water quality in an urban river

Excitation–emission matrix fluorescence spectroscopy combined with multivariable analysis was employed to discriminate structural component of dissolved organic matter (DOM) in Xihe River, an urban river, located in western Shenyang City of China, and to reveal its correlation with water quality. Eight water samples were collected along the river across the centralized wastewater-discharge region and the dispersed wastewater-discharge region. Water quality had deeply deteriorated in the river. Based on DOM fluorescence spectroscopic properties, DOM was composed of tyrosine-like, tryptophan-like, soluble microbial by-product-like, fulvic-like and humic-like materials, among which protein-like material was dominant in the DOM fractions. The DOM in the centralized wastewater-discharge region had a lower level of aromaticity than that in the dispersed wastewater-discharge region, and its humification degree was lower than that in the latter too. Key factors for the trophic state contained NH4-N, DO, DOC, TP, Φ2,n and Φ4,n by multivariable analysis. DOM was mainly derived from treated and untreated industrial wastewater with weak biodegradability.

Enhanced performance of immobilized laccase in electrospun fibrous membranes by carbon nanotubes modification and its application for bisphenol A removal from water

Multi-walled carbon nanotubes (MWCNTs) were used as modified materials to improve the performance of laccase-carrying electrospun fibrous membranes (LCEFMs). The MWCNTs modified LCEFMs (MWCNTs-LCEFMs) were successfully fabricated via emulsion electrospinning, with active laccase and MWCNTs encapsulated inside the fibers. After modified by an optimal amount (1.5wt%, vs. polymer) of MWCNTs, the obtained MWCNTs-LCEFMs showed not only higher activity recovery (85.3%, vs. free laccase) than LCEFMs (71.2%), but also better storage and operational stability, which were mainly attributed to the promoted electron transfer in laccase-catalytic reaction. Furthermore, the specific surface area and tensile strength of MWCNTs-LCEFMs have also been enhanced nearly 2 and 3 times than those of LCEFMs, respectively. The MWCNTs-LCEFMs were applied to remove the widespread bisphenol A from water, where their removal efficiency reached above 90%, with the degradation efficiency accounting for over 80%, and their adsorption efficiency increased about 45% than that of LCEFMs. In addition, the endurances of MWCNTs-LCEFMs to environmental factors such as pH and temperature were also improved.

Occurrence and distribution of phthalic acid esters and phenols in Hun River Watersheds

The Xi River (XR) and Pu River (PR) are the tributaries of Hun River Watersheds (HRW), located in Liao River Basin (LRB), northeast China. These riverine waters are historically polluted by effluents from printing and dyeing enterprises, and pharmaceutical and chemical industries. The concentrations of phthalic acid esters (PAEs), e.g., dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), diisobutyl phthalate (DIBP), di-n-octyl phthalate (DNOP) and bis(2-ethylhexyl) phthalate (DEHP), as well as phenols including phenol, 4-methylphenol, 2,3-dimethylphenol, 2,4-dimethylphenol, 3,5-dimethylphenol, 2,4,6-trimethylphenol, 2,4-di-tert-butylphenol and 2,6-di-tert-butyl-4-ethylphenolxa0in surface water of the XR and PR were determined by gas chromatograph (GC) coupled with a mass spectrometer (MS), respectively, during spring (dry), summer (wet) and autumn (normal) seasons. DMP, DIBP, DBP, phenol, 4-methylphenol and 3,5-dimethylphenol were identified as the dominant pollutants in the XR, and DBP, DIBP, DEHP and phenol were the main pollutants in the PR. Seasonal variations of the geometric mean concentrations in the XR ranged from 6.88 to 19.5xa0μg/L for ∑6PAEs and 24.5–1195xa0μg/L for ∑8phenols with the highest level in summer. The temporal distribution of ∑6PAEs or ∑8phenols in the PR was similar to that in the XR, i.e. the highest levels were observed in summer (24.1xa0μg/L for ∑6PAEs and 26.8xa0μg/L for ∑8phenols).The concentrations of pollutants were highly variable across sampling sites. The geographic concentrations of ∑6PAEs were in the range of 9.92–17.9xa0μg/L in the XR and 7.42–37.6xa0μg/L in the PR. As for ∑8phenols, the greater spatial variations were observed, ranging from 14.0–2008xa0μg/L in the XR and from 4.00 to 80.5xa0μg/L in the PR. Cluster analysis (CA) showed that the 19 sampling stations were divided into three clusters: cluster A was made up of the majority of sampling sites in the PR, slightly polluted by PAEs and phenols; cluster B consisted of the sites from both the XR and PR; cluster C included the sampling sites in the XR, where was heavily polluted by PAEs and phenols.

Spatial distribution and diversity of microbial community in large-scale constructed wetland of the Liao River Conservation Area

Microbial communities play a key role in wetland water purification and nitrogen cycling. The spatial distribution and diversity of total bacteria in large-scale constructed wetland were investigated by polymerase chain reaction-denaturing gradient gel electrophoresis. The abundance of nitrogen related functional bacteria were measured by real-time PCR using specific primers. The results showed that the diversity of total bacterial community decreased from the inlet zone (Shannon–Wiener index, H′xa0=xa03.471) to the outlet zone (H′xa0=xa02.566), so did the species richness and evenness. The dominant bacteria of the wetland were Proteobacteria, Acidobacteria and Bacilli. The abundance of amoA gene was higher than those of another two functional genes. There was significant correlation between the abundance of amoA gene and pH (rxa0=xa00.852), DO (rxa0=xa0−0.595), NH4+ (rxa0=xa00.595) and NO3− (rxa0=xa00.726) concentrations. The abundance of nosZ gene correlated with the DOC concentration (rxa0=xa0−0.614). The ratio of amoA/Nitrospira showed significant correlation with NH4+ concentration (rxa0=xa00.641), while the ratios of amoA/nosZ (rxa0=xa0−0.801) and Nitrospia/nosZ (rxa0=xa0−0.610) could reflect the NO2− concentrations. Therefore, the three ratios of nitrogen related functional genes may serve as new biological indicators for wetland condition assessment.

An novel identification method of the environmental risk sources for surface water pollution accidents in chemical industrial parks.

The chemical industry is a major source of various pollution accidents. Improving the management level of risk sources for pollution accidents has become an urgent demand for most industrialized countries. In pollution accidents, the released chemicals harm the receptors to some extent depending on their sensitivity or susceptibility. Therefore, identifying the potential risk sources from such a large number of chemical enterprises has become pressingly urgent. Based on the simulation of the whole accident process, a novel and expandable identification method for risk sources causing water pollution accidents is presented. The newly developed approach, by analyzing and stimulating the whole process of a pollution accident between sources and receptors, can be applied to identify risk sources, especially on the nationwide scale. Three major types of losses, such as social, economic and ecological losses, were normalized, analyzed and used for overall consequence modeling. A specific case study area, located in a chemical industry park (CIP) along the Yangtze River in Jiangsu Province, China, was selected to test the potential of the identification method. The results showed that there were four risk sources for pollution accidents in this CIP. Aniline leakage in the HS Chemical Plant would lead to the most serious impact on the surrounding water environment. This potential accident would severely damage the ecosystem up to 3.8 km downstream of Yangtze River, and lead to pollution over a distance stretching to 73.7 km downstream. The proposed method is easily extended to the nationwide identification of potential risk sources.

Risk assessment methodology for Shenyang Chemical Industrial Park based on fuzzy comprehensive evaluation

Risk assessment methodology for chemicals in Shenyang Chemical Industrial Park (SCIP) was established from the realities of frequent environmental pollution emergencies, just for the sake of quantitatively describing the risk levels of the chemicals, and for conducting priority control for those typical ones among them. Meanwhile vapor pressure (PV), median lethal concentration (LC50), combustibility and explosibility (CE), popularity (P) and detection frequency (DF) are selected as the risk assessment index for the chemicals, and then the weight from each assessment indicator on the surveillance levels for those chemicals has been identified. Finally, Fuzzy Comprehensive Evaluation (FCE) was adopted to work out the surveillance assessment level for each chemical in SCIP. The results show that 14 chemicals with relatively high-risk levels have been identified based on the above methods. Study on the risk assessment methodology for SCIP shall avail judgment on the risk levels for chemicals, allowing better management and control for chemicals accordingly.

Treatment of berberine hydrochloride pharmaceutical wastewater by O3/UV/H2O2 advanced oxidation process

O3/UV/H2O2 advanced oxidation process (AOP) was employed to degrade antibiotic berberine hydrochloride (BH) in pharmaceutical wastewater. The effects of initial solution pH, H2O2 dosage and O3 dosage on the berberine hydrochloride removal performance were investigated with synthetic wastewater. The optimum conditions of initial pH value of 7.0, H2O2 dosage of 3.0xa0mM, O3 dosage of 10.3xa0mg/min and the reaction time of 45xa0min were determined and the removal efficiency of berberine hydrochloride (C0xa0=xa01500xa0mg/L) reached 94.1xa0%. A small amount addition of H2O2 to O3/UV system greatly improved the berberine hydrochloride removal efficiency. The variations of pH value, ammonium nitrogen and conductivity were analyzed to confirm the degradation of BH. Under the optimal experimental conditions, O3/UV/H2O2 was used to treat the actual berberine hydrochloride wastewater. It demonstrated that the biodegradability of berberine hydrochloride wastewater was obviously promoted and the ratio of biochemical oxygen demand (BOD5) to chemical oxygen demand (COD) was improved from 0.02 up to 0.29, 15 times greater than that of original wastewater. The costs of four O3-based advanced oxidation processes, O3, O3/UV, O3/H2O2 and O3/UV/H2O2, were also calculated and compared, indicating that O3/UV/H2O2 was the best choice taking into account both the cost and the efficiency. It suggested that the O3/UV/H2O2 advanced oxidation process could not only remove berberine hydrochloride more efficiently but also reduce the costs significantly.