The north of Liaodong Bay is one of the most severely polluted areas in Bohai Sea. Because the self-purification capacity from the sea water exchange process is limited, the pollutants from the land and river sources cannot be completed degraded and an obviously contaminated zone was formed in the north of Liaodong Bay. Therefore the self-purification capacity from biological process is essential for maintaining ecosystem balance. Marine heterotrophic bacteria play an important role in degradation of the dissolved organic matters and constitution of the primary production in the coastal areas. The shift of water temperature between winter and summer is about 28°C in the north of Liaodong Bay, which causes changes in the self-purification capacity of the sea area. Certain indexes of water quality in Liaodong Bay were investigated in order to detect how these indexes response to the changing of water temperature. The experimental results show that COD, DO and the concentration of fecal coliform vary a little with the changing of water temperature; TBC increases dramatically when the water temperature is over 16°C; and TBC in summer is 30 times more than that in winter. By this study, the paper provides a reference to assess the environmental purification capacity of the sea area during different seasons.

The remediation of dye-contaminated soil using silent discharge plasma in dielectric barrier discharge (DBD) reactor was reported in this study. Acid scarlet GR was selected as the representative of azo dye pollutants. Effects of applied voltage, discharge frequency, and gas flow rate on Acid scarlet GR treatment effect which were characterized by degradation efficiency and the change of chemical oxygen demand (COD) during the degradation were investigated. The decolorization rate of Acid scarlet GR in the soil increased with the applied voltage and discharge frequency, and the optimal gas flow rate was obtained at 1.0 L min⁻¹. The energy efficiency was clearly enhanced by way of increasing the amount of contaminated soil in the DBD reactor finitely. The degradation efficiency of Acid scarlet GR and the removal of COD value were achieved 93 % and 74 % after 25-min discharge treatment, respectively. The results indicated that the DBD remediation system was able to degrade Acid scarlet GR in the soil quickly and efficiently. This study is expected to provide a possible pathway of Acid scarlet GR degradation in soil.

Zn²⁺was added to one of the two identical bench-scale upflow anaerobic sludge blanket (UASB) reactors in steady-state period treating swine wastewater to evaluate the effects of Zn²⁺on performance and methanogenic population. Real-time quantitative PCR (QPCR) was used to quantify the 16S rRNA gene concentrations of the four methanogenic orders. In both reactors, the hydraulic retention time (HRT) was sustained at 48 h and the inner temperature was kept at 35 °C. Both promotion and inhibition of Zn²⁺on chemical oxygen demand (COD) removal, methane production and methanogens community were observed in accordance with different Zn²⁺dosages. COD removal rate and methane production reacted in the same way as methanogens, suggesting that the impact of Zn²⁺on the methanogenic community was the critical reason that caused the changes of UASB performance in treating swine wastewater with unstable Zn²⁺concentration. Among the methanogenic community, Methanomicrobiales (MMB) was the dominant group which got visibly impacted by the dosed Zn²⁺. Overall, lower concentration of Zn²⁺, e.g., less than 17.8 mg/L, was supposed to be advisable for a stable and high efficient treatment of swine wastewater by UASB reactor in practice.

The application of combined electrochemical and photochemical techniques for the degradation of real textile effluent is presented. It is demonstrated that the simultaneous use of both techniques, in conjunction with in situ generation of free chlorine and its subsequent photolysis, is a promising technique for removing color and chemical oxygen demand (COD) from effluents. Crucially, the combination of electrochemical and photochemical techniques leads to lower quantities of chlorine-containing degradation by-products being produced and no overall increase in toxicity. Over the treatment times studied, up to 65 % less chloride-containing degradation by-products are formed while at the same time greater rates of color and COD removal are achieved.

Zn⁰-activated persulfate as a novel and potential approach to the degradation of azo dyes has hardly been reported. In this study, the effects of initial pH, persulfate concentration, Zn⁰ dosage, and temperature on the decomposition of Congo red (CR), an azo dye, were investigated. The results demonstrated that Zn⁰-activated persulfate could effectively mineralize CR. At the initial pH 5.5 and 25 °C, chemical oxygen demand (COD) and total organic carbon (TOC) in the solution with 95 mg/L CR decreased by approximately 87 and 60 %, respectively, within 3 h. The optimum dosages of persulfate and Zn⁰ were approximately 95 mg/L and 2 g/L, respectively. The highest decolorization efficiency of CR was realized at the initial pH 5.5. Both ·OH and SO₄ ⁻· contributed to the degradation of CR, and the spectra of free radicals showed that SO₄ ⁻· was gradually converted to ·OH with pH increasing from weak acidic to neutral condition.

The influence of structure on degradation of five halogenated phenols (XPs) by UV/H₂O₂process was investigated. The combined influence of type or number of substituents and UV/H₂O₂process parameters (pH and [H₂O₂]) on the degradation kinetics of 2-fluorophenol (2-FP), 2-chlorophenol (2-CP), 2-bromophenol (2-BP), 2,4-dichlorophenol (2,4-DCP), and 2,4,6-trichlorophenol (2,4,6-TCP) was studied using modified miscellaneous 3³full factorial design and response surface modeling (RSM). Studied XPs obey first-order degradation kinetics within the investigated range of process parameters. Determined degradation rate constants (kₒbₛ) were correlated with process and structural parameters by the quadratic polynomial models. Analysis of variance (ANOVA) demonstrated RSM models’ accuracy and showed that, in addition to pH and [H₂O₂], model terms related with the pollutant structure are highly influential. kₒbₛof mono-XPs follow the decreasing order 2-FP, 2-CP, and 2-BP, while CPs follow the decreasing order 2-CP, 2,4-DCP, and 2,4,6-TCP. Biodegradability (biochemical oxygen demand (BOD)₅/chemical oxygen demand (COD)) and toxicity (TU) were evaluated prior to the treatment and at the reference time intervals. The observed differences are correlated with the structural characteristics of studied XPs.

The novel adsorbent Cu-impregnated activated coke (CAC) has been successfully prepared using a Cu(NO₃)₂solution impregnated activated coke (AC). The optimum preparation conditions of CAC are the concentration of Cu(NO₃)₂of 0.1 mol/L, pH of 6, loading time of 4 h, and loading temperature of 333 K. The characterizations of CAC are analyzed by N₂adsorption, X-ray diffraction, scanning electron microscope, and energy dispersive X-ray spectroscopy. Also the adsorption behavior of CAC to organic materials in TNT red water is studied. The adsorption data are simulated by Freundlich isotherm and Langmuir isotherm. Below 333 K Freundlich isotherm is more suitable, while Langmuir isotherm model is more fitted when the temperature is higher than 333 K. The adsorption kinetics follows a pseudo second-order model, and thermodynamic analysis indicates an endothermic and spontaneous adsorption processes, and the process appears to be controlled by the chemisorption process. Chemical oxygen demand of 85.34 % can be removed as CAC prepared under optimized conditions is used as absorbent. In summary, CAC has excellent absorption characteristics and can be used in the removal of organic materials from TNT red water.

TiO₂-mediated photodegradation is widely reported to degrade recalcitrant pollutants such as nitrophenolics. This paper investigated the TiO₂-mediated photodegradation of trinitrophenol (TNP) in aqueous solution irradiated by an artificial light source. About 28.4 % TNP degradation was attained over 450 min from an initial TNP concentration of 1,000 mg L⁻¹. Ionic chromatographic analysis further revealed the evolution of nitrite and nitrate anions and an unknown intermediate X during the photodegradation process. The trends of nitrite and nitrate anions indicate that the photodegradation process produced nitrite at first, which subsequently turned to nitrate in the presence of oxygen. The removal rate of COD was far slower than that of TNP, inferring the photodegradation reaction gradually mineralized the parent pollutants. The photodegradation of TNP could not proceed under anaerobic condition, presumably a result of oxygen deficiency that disabled the denitration process. Because of the volumetric loss of the test solution, follow-up irradiations were performed after addition of supplementary water. This follow-up irradiation period revealed that direct photolysis, i.e., irradiation in the absence of TiO₂photocatalysts, could not photodegrade TNP but gradually diminish the component X.

Performance of a laboratory-scale integrated baffled reactor for the treatment of raw palm oil mill effluent (POME) was investigated. Initially, the reactor was fed with diluted POME (COD = 1,830 mg/L and OLR = 0.46 g COD/L day) which was then increased gradually to actual concentration (COD = 45,500 mg/L and OLR = 11.38 g COD/L day). Reactor operation was studied in two different hydraulic retention times (HRTs) (4 and 6 days) using POME with no effluent-recycled feed and after alkalinity supplementation. Chemical oxygen demand (COD) removal of 79 and 83 % at an HRT of 4 and 6 days were attained at the highest organic loading rate (OLR = 11.38 g COD/L day). The presence of Arcella-like and Metopus-like species and pH profile in the bioreactor’s compartments imply that anaerobic system is active in the reactor throughout the study. Use of methanogen-enriched inocula, smooth OLR augmentation, and appropriate separation of acidogens and methanogens in the reactor were the reasons for satisfactory performances of the system.

A common weed, Imperata cylindrica (cogongrass), was used as a low-cost adsorbent for the adsorption of methylene blue (MB) and the process optimized. The effects of four factors, namely, shaking speed (100–300 rpm), pH (3–9), contact time (10–40 min) and adsorbent dosage (0.4–1.0 g), on colour removal and chemical oxygen demand (COD) reduction of MB were studied and optimized using fractional factorial design and response surface methodology. The two factors that play a vital role in the adsorption process are pH and adsorbent dosage. From the results, colour removal and COD reduction recorded coefficient of determination (r ²) values of 0.9600 and 0.9594, respectively. Optimum adsorption conditions, resulting in 99.09 % colour removal and 97.87 % COD reduction, were achieved at shaking speed of 100 rpm, pH 9, 40 min contact time and adsorbent dosage of 1.0 g. The adsorption systems for MB dye were found to fit the pseudo-second order model instead of the pseudo-first order model, while equilibrium studies showed that the adsorption process followed the Langmuir isotherm.