An ethanol-fed, sulfate-reducing anaerobic baffled reactor was operated over a period of 260 days to assess the effects of sequentially more acidic conditions (pH 4.5–2.5) on sulfate reduction and bacterial community. Results showed that the reactor could reduce sulfate and generate alkalinity at progressively lower pH values of 4.5, 3.5, and 2.5 in a synthetic wastewater containing 2500 mg/L sulfate. About 93.9% of the influent sulfate was removed at a rate of 4691 mg/L/day, and the effluent pH was increased to 6.8 even when challenged with influent pH as low as 2.5. Illumina MiSeq sequencing revealed that a step decrease in influent pH from 4.5 to 2.5 resulted in noticeable decrease in the biodiversity inside the sulfidogenic reactor. Additionally, complete and incomplete organic oxidizers Desulfobacter and Desulfovibrio were observed to be the most dominant sulfate reducers at pH 2.5, sustaining the low-pH, high-rate sulfate removal and alkalinity generation.

•TiO2/hydroniumjarosite with different TiO2 content was prepared using deposition–precipitation method.•The sample prepared with the TiO2/Fe3+ mole ratio of 75:25 exhibited the highest catalytic efficiency.•The enhanced catalytic activity can be attributed to the formation of TiO2/hydroniumjarosite heterostructure.In this paper, a series of novel TiO2/hydroniumjarosite composite photocatalysts were synthesized by deposition–precipitation method. XRD, UV–vis DRS, TEM, BET, PL spectra and EIS were used to characterize the composite photocatalysts. The photocatalytic performance of the composite catalysts were examined on the Cr(VI) reduction under ultraviolet irradiation in aqueous suspension. The results show that TiO2/hydroniumjarosite composites exhibit enhanced photocatalytic activity with a maximum reduction rate of 98.0%, while the Cr(VI) reduction efficiency is only 36.0% over P25 under the same conditions. The increased light absorption intensity and the decreased electron–hole pair recombination rate in TiO2 with the introduction of hydroniumjarosite are responsible for better catalytic property of TiO2/hydroniumjarosite catalysts. It would be of great promise for the industrial application of this catalyst with high potocatalytic performance to reduce Cr(VI) for wastewater treatment.

Polycyclic aromatic hydrocarbons (PAHs) were measured in 128 soil samples collected from Xiangfen County, Shanxi Province, China. Sixteen PAH congeners were identified at high concentrations (89–100 %), with the exceptions of Ace and Acy, and were used for statistical analysis. PAH concentrations ranged from 51.91 to 10,523.58 ng/g with a mean of 722.35 ng/g indicating severe pollution at the sample sites. Four-ring PAHs were predominant followed by 3- and 5-ring PAHs. Coal combustion was found to be the greatest contributor of PAHs to the local environment. An analysis of the spatial distribution of PAHs indicated the presence of relatively high concentrations in the northwest region of the county. A source identification analysis showed that Wulidun in Fencheng Town, Shangbeirong Village in Gucheng Town, and Yandian Village in Xincheng Town were the major sources of PAHs in Xiangfen County. Modeling results indicated that the distance among the sampling sites and these point sources had a large influence on the transfer of PAHs to the soils.

A filamentous fungus strain OU5 was isolated from a soil sample for its ability to produce rich exopolymers (EPS), with high flocculation capability towards kaolin suspension and swine wastewater, at low-carbon source conditions. EPS from strain OU5 was extracted and characterized to determine its flocculating behavior and active constituents involved in the flocculation. Strain OU5 was identified as Talaromyces trachyspermus by 18S rDNA–ITS gene sequencing and morphological observation. The extracted EPS was a novel proteoglycan (designated as BF–OU5) composed of 84.6% (w/w) polysaccharides and 15.2% (w/w) proteins. The enzymatic digestion tests revealed that the polysaccharides in BF–OU5, composed of 67% glucose, 16.4% mannose, 8.6% xylose and 8% galactose, contributed to 99.7% of flocculating capacity and were the major active ingredients in the flocculation. By contrast, the proteins in BF–OU5 only had minor roles in the flocculation. The presence of hydroxyl, amide, carboxyl and methoxyl functional groups in BF–OU5, and the high molecular weight (1.053 × 105–2.970 × 105 Da) as well as the structure of a spherical conformation with inner pores and channels made of cross-linked netted textures contributed to the flocculation. A dosage of 20 mg/l BF–OU5 initiated more than 92.5% of flocculating efficiency towards kaolin suspension without any added coagulants; its flocculability was stable over a wide range of pH (4.0–8.0) and temperature (20°C–100°C). Treatment of swine wastewater using BF–OU5 achieved 52.1% flocculating removal for chemical oxygen demand, 39.7% for Kjeldahl nitrogen, 18.6% for NH4+–N, 21.5% for total phosphorus, and 75% for turbidity.