China’s rapid economic growth is accompanied by seriously environmental pollution. It is the primary task of Chinese government to effectively improve the environmental pollution status while maintaining the rapid and stable economic development. As a new environment governance method, this paper analyzes both environmental and economic effect of third-party governance model concerning “the one who makes pollution makes payment”. Firstly, Deng grey relational analysis and principal component analysis have been adopted to calculate the environmental governance coefficients and to rank the effect of environmental governance for all sample cities. And the consistency of results of the two methods has been evaluated according to Kendall-W coefficients. The two methods reach the same conclusion that the sample cities adopting the third-party governance model can improve the environmental pollution status more effectively. Secondly, Granger causality test is used to analyze the relationship between the third-party model and economic growth. It is concluded that the third-party governance model could effectively promote economic growth of local cities. Lastly, this paper puts forward some measures and improvement methods to promote the third-party governance model in China.

An in situ horizontal well (IHW) fan-shaped test tank was constructed in the laboratory. And nitrate removal rates were analyzed under different hydraulic loads. When the initial concentration of groundwater nitrate-N was 25 mg/L and the hydraulic load increased from 0.78 to 3.90 m³/(m² day), the results show that the nitrate-N concentration was less than 1.25 mg/L after the denitrification process stabilized. Additionally, the nitrate-N removal rate was over 95%. The concentration of nitrite-N was still below 1 mg/L, and the level of ammonia-N was between 0.5 and 1.00 mg/L. No increase in nitrite-N and ammonia-N concentration occurred during the test. The hydraulic conductivity of the medium in the horizontal well showed little variation, ranging from 34.09 to 31.64 m/day, indicating that there was no blockage caused by microbial growth in the IHW during the test. In addition, no ethanol was detected in the test tank except for the horizontal well, revealing that ethanol did not diffuse into the surrounding aquifer. Therefore, when the concentration of groundwater nitrate contamination is 25 mg/L, the hydraulic load under the IHW test tank condition is 3.90 m³/(m² day). The IHW test tank had a stable and good biological denitrification effect, and it can provide certain reference significance for in situ remediation of nitrate-contaminated groundwater.

In the present study, a multistage route is proposed for the treatment of biodiesel industry wastewater (BWW) containing around 1000 mg L⁻¹ of total organic carbon (TOC), 3500 mg L⁻¹ of chemical oxygen demand (COD), and 1325 mg L⁻¹ of oil and grease. Initially, BWW aerobic biodegradability was assessed via Zhan-Wellens biodegradability test to confirm the appropriate treatment route. Then, a hybrid moving bed bioreactor (MBBR) system was chosen as the first treatment stage. The hybrid MBBR achieved 69 and 68% removal of COD and TOC removals, respectively, and provided great conditions for biomass growth. The bacterial community present in the hybrid MBBR was investigated by PCR-DGGE and potential biodegraders were identified such as: members of Desulfuromonadales, Nocardioidaceae and Pseudomonadaceae. Since biodegradation in the hybrid MBBR alone was unable to meet quality requirements, advanced oxidation processes, such as Fenton and photo-Fenton, were optimized for application as additional treatment stages. Physicochemical properties and acute toxicity of BWW were analyzed after the multistage routes: hybrid MBBR + Fenton, hybrid MBBR + photo-Fenton and hybrid MBBR + UV-C₂₅₄ₙₘ/H₂O₂. Hybrid MBBR + Fenton or photo-Fenton showed overall COD removal efficiencies greater than 95% and removed acute toxicity, thus being appropriate integrated routes for the treatment of real BWW. Graphical abstract ᅟ

Full-scale application of heterogeneous photocatalysis for industrial wastewater treatment remains a challenge because of the complex nature of these matrices and the potential to form toxic by-products during treatment. A recent unsuccessful attempt to find adequate conditions for TiO₂/UV treatment of a cotton dyeing textile mill led to this study on the treatability of mixtures of the dyes used in the greatest amounts at the mill and therefore most likely to be present in mill effluent. Four reactive and three vat dyes were mixed in different combinations and treated (10 mg/L of each dye, 0.5 mg/L TiO₂, pH 4) to evaluate the influence of the different dyes on ADMI color, chemical oxygen demand (COD), and acute toxicity. While ADMI color removal was similar in all dye mixtures, COD removal was higher when vat dyes were absent. When treated individually, vat dyes exhibited greater recalcitrance, with no ADMI color removal and COD removals of less than 30%. Toxicity to Daphnia similis was decreased or eliminated from dye mixtures that exhibited the highest COD removals and corresponded to those in which reactive dyes were partially degraded. For raw textile mill effluent, photocatalysis reduced but did not eliminate treated effluent toxicity (EC50 = 26.8%).

Since the introduction of environmental legislations and directives, the impact of combined sewer overflows (CSO) on receiving water bodies has become a priority concern in water and wastewater treatment industry. Time-consuming and expensive local sampling and monitoring campaigns are usually carried out to estimate the characteristic flow and pollutant concentrations of CSO water. This study focuses on estimating the frequency and duration of wet-weather events and their impacts on influent flow and wastewater characteristics of the largest Italian wastewater treatment plant (WWTP) located in Castiglione Torinese. Eight years (viz. 2009–2016) of historical data in addition to arithmetic mean daily precipitation rates (PI) of the plant catchment area are elaborated. Relationships between PI and volumetric influent flow rate (Qᵢₙ), chemical oxygen demand (COD), ammonium (N-NH₄), and total suspended solids (TSS) are investigated. A time series data mining (TSDM) method is implemented with MATLAB computing package for segmentation of time series by use of a sliding window algorithm (SWA) to partition the available records associated with wet and dry weather events. According to the TSDM results, a case-specific wet-weather definition is proposed for the Castiglione Torinese WWTP. Two significant weather-based influent scenarios are assessed by kernel density estimation. The results confirm that the method suggested within this study based on plant routinely collected data can be used for planning the emergency response and long-term preparedness for extreme climate conditions in a WWTP. Implementing the obtained results in dynamic process simulation models can improve the plant operational efficiency in managing the fluctuating loads.

High contents of azo dyes and heavy metals enter surface waters with the wastewater from dying and dye-manufacturing industries and pose serious threat to fish. In the present study, changes in the ultra-morphological features of the scale have been evaluated as indicators of the stress of lethal and sublethal concentrations of an azo dye Acid Black-1 (AB-1, CI 20470), zinc (Zn), and their mixture AB-1 + Zn to Labeo rohita. Fish were exposed for 96 h to lethal concentration (LC) causing 0–70% mortality, i.e., LC₀, LC₂₀, LC₅₀, and LC₇₀ of AB-1 (4, 6, 8, and 10 mg/L respectively) and Zn (25, 50, 55, and 60 mg/L respectively) and LC₀, LC₅₀, and LC₇₀ of AB-1 + Zn (2 + 15, 2 + 20, and 2 + 25 mg/L respectively). Subchronic exposures of 150 days were given to 1/12, 1/6, and 1/3 of 96 h LC₅₀ values of AB-1, Zn, and AB-1 + Zn. After each exposure, the fish were kept for a recovery period of 90 days. Breakage of circuli, erosion and breakage of lepidonts, uprooting of tubercles, and disappearance of intercircular teeth were observed in all the fish, after 96 h exposure to AB-1, Zn, and AB-1 + Zn. However, damage to focus and holes were common on the scales of Zn-exposed fish. The mixture AB-1 + Zn was more toxic than either of the two as loss of circuli, lepidonts, and intercircular teeth, and sloughing of surface were observed in the scales after 96 h exposure to 2 + 25 mg/L. Damage at this concentration was more than the damage at 8/10 mg/L AB-1 and 55/60 mg/L Zn. After 150 days of exposure, damage due to sublethal concentrations was more than the damage due to all the concentrations of 96 h exposure. Irregular and sloughed circuli were common at 2 + 1.79 and 2 + 3.59 mg/L AB-1 + Zn. Cracks all over the surface (2 + 7.18 mg/L), calcium projections (2 + 3.59 and 2 + 7.18 mg/L), and holes (2 + 7.18 mg/L) hint towards synergistic toxicity of the mixture. It seems that the present dye and metal formed complexes with collagen and osteoblastic cells of the scale that caused an increase in damage during the post-exposure period. Scales of 2 + 7.18 mg/L AB-1 + Zn exposed fish were completely devoid of the normal architectural pattern on the 90th day of the recovery period. Changes in the ultra-morphology of scales at LC₀ (0% mortality) and sublethal concentrations show that these are early indicators of the stress of minute quantities of dyes and metals in water. This is a first report on the cumulative toxicity of the two most abundant components of textile industry effluents.

As transcriptomic studies are becoming more and more common, it is important to ensure that the RNA used in the analyses is of good quality. The RNA integrity may be compromised by storage temperature or freeze-thaw cycles, but these have not been well studied in poikilothermic fishes. This work studied the effects of tissue storage time and temperature, and freeze-thaw cycles of tissue and extracted RNA on RNA integrity in brown trout (Salmo trutta L.) liver. The storage time and temperature had an effect on RNA integrity, but RNA suitable for quantitative reverse transcription PCR (RT-qPCR) (RIN > 7) was still obtained from samples preserved at − 20 °C for 6 months. Freeze-thaw cycles of tissue or RNA did not compromise the integrity of RNA. RNA degradation had an effect on RT-qPCR results, and the effect depended on gene. The RT-qPCR analysis of historical samples from a bleached kraft pulp mill effluent exposure in 1984 revealed no significant cyp1a induction. Recommendations are given for the preservation and handling procedures of samples designated for transcriptomic analyses.

CO₂, SO₂, and NO are the main components of flue gas and can cause serious environmental issues. Utilization of these compounds in oleaginous microalgae cultivation not only could reduce air pollution but could also produce feedstock for biodiesel production. However, the continuous input of SO₂ and NO inhibits microalgal growth. In this study, the toxicity of simulated flue gas (15% CO₂, 0.03% SO₂, and 0.03% NO, balanced with N₂) was reduced through automatic pH feedback control. Integrated lipid production and CO₂ fixation with the removal of SO₂ and NO was achieved. Using this technique, a lipid content of 38.0% DW was achieved in Chlorella pyrenoidosa XQ-20044. The lipid composition and fatty acid profile indicated that lipid production by C. pyrenoidosa XQ-20044 cultured with flue gas is suitable as a biodiesel feedstock; 81.2% of the total lipids were neutral lipids and 99.5% of the total fatty acids were C16 and C18. The ratio of saturated fatty acids to monounsaturated fatty acids in the microalgal lipid content was 74.5%. In addition, CO₂, SO₂, and NO from the simulated flue gas were fixed and converted to biomass and lipids with a removal efficiency of 95.9%, 100%, and 84.2%, respectively. Furthermore, the utilization efficiencies of CO₂, SO₂, and NO were equal to or very close to their removal efficiencies. These results provide a novel strategy for combining biodiesel production with biofixation of flue gas.

A consortium of highly degrading microorganisms was used in an integrated bioaugmentation/electrocoagulation process for treating olive mill wastewater. The system was investigated for treating 1 m³ day⁻¹, at a pilot scale, for 2 years; hydraulic loading rate and organic loading rate were 2880 l m⁻² day⁻¹ and 37,930 g COD m⁻² day⁻¹, respectively. Average removal efficiency for COD, oils, and total phenols was 63.9%, 85.2%, and 43.6%, respectively. The olive mill consortium, OMC, consisted of seven actinomycete strains. The strains were confirmed, by 16S rDNA analysis, to belong to five Streptomyces, one Kitasatospora, and one Micromonospora strains, at 100–99.06% similarities. Hydrolytic enzyme activities of OMC strains were remarkably higher for degrading cellulosic and lipid constituents (enzyme-cumulative indices, 14–16.1), than the phenolic constituents (indices, 4.1–6.5). The establishment of actinomycetes in the treatment system was indicated by their increased counts in the biofilm at the end of the biofilter, reaching 13-fold higher than that in the control bed. The treated effluent was toxic to the seedlings of Jatropha curcas (Jatropha) and Simmondsia chinensis (Jojoba). Though its application in irrigation of 3-year-old Jatropha shrubs, significantly, enhanced the fruit yield up to 1.85-fold higher than the control, without affecting the seed oil content, after 3-month application, the irrigated soil showed insignificant changes in its biochemical properties. This developed bioaugmentation/electrocoagulation process can treat wastewater with extremely high organic strength, while its approximate construction and operational costs are limited to 0.03 and 0.51 US$ m⁻³, respectively. It produces a treated effluent that can be reused in irrigation of specific plants. Graphical abstract

This study aimed to explore the nitrogen and phosphorus removal performance of the horizontal submerged constructed wetland (HSCW) with Ti-bearing blast furnace slag (T). Another two HSCWs, with the converter steelmaking slag (G) and the stone (S) as wetland substrates, respectively, were simultaneously running as control. The results showed that the nitrogen and phosphorus removal capacities of the T-HSCW were generally better than those of another two HSCWs. When the hydraulic retention time (HRT) was 6 days, the effluent concentrations of ammonia nitrogen (NH₄⁺-N) and total nitrogen (TN) were 6.66 mg L⁻¹ and 14.02 mg L⁻¹, respectively, and the removal rates of NH₄⁺-N and TN reached 77.54% and 71.07%, respectively. The T-HSCW had better removal efficiency of phosphorus. The effluent concentration of total phosphorus (TP) was lower than 0.3 mg L⁻¹, and the maximum removal rate could reach 98%. Through the characterization of the three substrates before and after experiments, it was found that the removal of nitrogen and phosphorus by T and G mainly relied on chemical adsorption, while S mainly relied on physical adsorption. Ti could also promote the absorption of nitrogen by plants and increase the nitrogen removal capacity of T-HSCWs.