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Octylphenol polyethoxylate (OP n EO) is a potential endocrine-disrupting chemical. Biodegradation of OP n EO was investigated using the bacterium Aeromonas sp. TXBc10 isolated from the influent of ...

In recent years, 2, 5-furandicarboxylic acid (FDCA) has attracted much attention as the precursor of bio-polyester materials. A coupled process of ultrasonic-assisted dilute acid pretreatment and MnO2 was designed in this study to directly produce FDCA from lignocellulosic biomass, which is different from the traditional preparation process. Moreover, the critical parameters in the process were analyzed and optimized by the response surface method. The yield of FDCA could reach 52.1% under the optimal conditions. The reaction mechanism indicated that heavy metal elements in lignocellulosic biomass could play the role of the Lewis acid catalyst to promote the formation of FDCA to a certain extent. With the increase of temperature, the heavy metals transfer in biomass from the solid phase to the liquid phase increased, but most of them remain in the former. Therefore, further purification and treatment measures are worthy of attention.

Volatile fatty acids (VFAs) production plays an important role in the process of anaerobic digestion (AD), which is often the critical factor determining the metabolic pathways and energy recovery efficiency. Fermenting bacteria and acetogenic bacteria are in syntrophic relations during AD. Thus, clear elucidation of the interspecies electron transfer and energetic mechanisms among syntrophic bacteria is essential for optimization of acidogenic. This review aims to discuss the electron transfer and energetic mechanism in syntrophic processes between fermenting bacteria and acetogenic bacteria during VFAs production. Homoacetogenesis also plays a role in the syntrophic system by converting H2 and CO2 to acetate. Potential applications of these syntrophic activities in bioelectrochemical system and value-added product recovery from AD of organic wastes are also discussed. The study of acidogenic syntrophic relations is in its early stages, and additional investigation is required to better understand the mechanism of syntrophic relations.

Wastewater treatment is in a dilemma: more energy and efforts have to be put forth to obtain an effluent with better quality, while a significant amount of sludge is generated and the treatment or disposal expenses are high. Even if the sludge is disposed of properly, the components can be released and pollute the environment again. Therefore, conversion and recovery of the contaminants to resources is the way out of the dilemma. An ion exchange membrane (IEM) is a special type of membrane, which allows charged solutes to pass through it while retaining uncharged components. Attributed to this character, IEMs are taking more important roles in separation and conversion processes recently. They act as key elements in many resource recovery systems, such as in separation and concentration, salt valorization, energy conversion, and even in microbial systems. This review summarizes the important processes for waste conversion and resource recovery from wastewaters by using IEMs. Drawbacks and perspectives are...

Performance of two novel designed anaerobic membrane bioreactor (AnMBRs) for wastewater treatment at long hydraulic retention time (HRT, 47 days) and high sludge concentration (22 g·L−1) was investigated. Results showed steady chemical oxygen demand (COD) removal (> 98%) and mean biogas generation of 0.29 LCH4·g−1COD. Average permeates flux of 58.70 L·m−2·h−1 and 54.00 L·m−2·h−1 were achieved for reactors A and B, respectively. On top of reactor configuration, long HRT caused biofilm reduction by heterotrophic bacteria Chloroflexi resulting in high membrane flux. Mean total membrane resistances (2.23 × 109 m−1) and fouling rates (4.00 × 108 m−1·day−1) of both reactors were low suggesting better membrane fouling control ability of both AnMBRs. Effluent quality analysis showed the effluent soluble microbial products (SMP) were dominated by proteins compared to carbohydrates, and specific ultraviolet absorbance (SUVA) analysis revealed effluent from both reactors had low aromaticity with SUVA < 1 (L·mg−1·m−1) except for the first ten days.

Recently, efficient disposal of food waste (FW) with potential resource recovery has attracted great attentions. Due to its easily biodegradable nature, rich nutrient availability and high moisture content, FW is regarded as favorable substrate for anaerobic digestion (AD). Both waste disposal and energy recovery can be fulfilled during AD of FW. Volatile fatty acids (VFAs) which are the products of the first-two stages of AD, are widely applied in chemical industry as platform chemicals recently. Concentration and distribution of VFAs is the result of acidogenic metabolic pathways, which can be affected by the micro-environment (e.g. pH) in the digester. Hence, the clear elucidation of the acidogenic metabolic pathways is essential for optimization of acidogenic process for efficient product recovery. This review summarizes major acidogenic metabolic pathways and regulating strategies for enhancing VFAs recovery during acidogenic fermentation of FW.

Resource recovery from piggery biogas slurry has become an inevitable demand for sustainable development of pig industry. Microalgae show great potential in recovering nitrogen and phosphorus from piggery slurry, but struggle to utilize organic pollutants, as most of them are inert components (e.g., humic acids, HAs). In this study, nano-TiO2 was used to enhance the utilization of HAs by microalgae from piggery biogas slurry. Results showed that the optimal conditions for microalgal growth and HAs removal by the microalgae-TiO2 coupling system were TiO2 dosage of 0.30 g/L, microalgal inoculation concentration of 0.40 g/L, light intensity of 360 µmol photon/(m2·s) and temperature of 30 °C, with the microalgal chlorophyll concentration of 6.51 mg/L and HAs removal efficiency of 50.14%. Analysis of HAs composition variations in the piggery biogas slurry indicated that the decrease of HAs was caused by their decomposition into small molecules under the photocatalytic reactions of TiO2.

A bacterial consortium for efficient decontamination of high-concentration Fe–Mn acid mine drainage (AMD) was successfully isolated. The removal efficiencies of Fe and Mn were effective, reaching 99.8 % and 98.6 %, respectively. High-throughput sequencing of the 16S rRNA genes demonstrated that the microbial community had changed substantially during the treatment. The Fe–Mn oxidizing bacteria Flavobacterium, Brevundimonas, Stenotrophomonas and Thermomonas became dominant genera, suggesting that they might play vital roles in Fe and Mn removal. Moreover, the pH of culture increased obviously after incubation, which was benefit for depositing Fe and Mn from AMD. The specific surface area of the biogenic Fe–Mn oxides was 108–121 m2/g, and the surface contained reactive oxygen functional groups (–OH and −COOH), which also improved Fe and Mn removal efficiency. Thus, this study provides an alternative method to treat AMD containing high concentrations of Fe and Mn.

Ivermectin is now being used as a substitute for toxic organic biocide in marine antifouling coatings due to its environmentally friendly nature and the efficacy against parasites. However, the release performance of ivermectin from the hydrolyzed acrylic-based resin into the seawater is not clear. Moreover, the efficiency and mechanism of ivermectin in preventing biofilm or slime formation have not been fully investigated. In this study, a coating was developed by mixing ivermectin with an acrylic-based resin, silyl acrylate copolymer, and a 45-day in situ antifouling test was conducted in the Yellow Sea. Direct observation and confocal microscope investigation indicated that the polymer coating with ivermectin was effective against biofilm formation. High-throughput sequencing analysis showed that ivermectin can selectively inhibit the adhesion of microorganisms. Abundances of Gammaproteobacteria and Alphaproteobacteria decreased significantly with the increased concentration of ivermectin. As for the eukaryote community, species of Stolidobranchia and unidentified_Bacillariophyceae were proved to be sensitive to ivermectin. Therefore, the ivermectin/silyl acrylate copolymer coating is a promising substitute for marine antifouling material.

Rice straw pretreated under various conditions of temperature, ranging from 200 to 220 °C, and time, from 60 to 240 s, was used as the substrate in an anaerobic biogas recovery process. Steam explosion-pretreated rice straw displayed a significant improvement in physicochemical properties compared to untreated rice straw. The biogas production rate increased in all pretreated rice straw systems with shortened start-up periods, and the highest biogas production rate reached 328.7 mL g−1 TS (total solid content) under steam explosion pretreatment conditions of 200 °C/120 s, corresponding to a 51% increase. In addition, upon pretreatment at 200 °C/120 s, the degradation rates of cellulose and hemicellulose in the system reached 53.46% and 49.54%, which were 13.72% and 16.79% higher than in the control, respectively. PCR-DGGE analysis showed that the distributions of specific species of bacteria and archaea varied among different samples. There were clear differences in the bacterial population between pretreated and untreated groups during the set-up period and early stage. During the mid and final stages, pretreated systems had more diverse communities in the digester than the untreated system. Steam explosion pretreatment of the rice straw also led to the earlier presence of cellulolytic bacteria. Furthermore, the species of cellulolytic bacteria in pretreated systems were Clostridium sp. while those in the untreated reactor were Pseudomonas sp. The succession of archaea in the microbial community at different stages in the pretreated and untreated systems was not as obvious as that of bacteria. The results indicate that the physicochemical properties of rice straw were altered by the steam explosion pretreatment, which led to more efficient biogas production due to changes in the bacterial and archaeal species in the pretreated system.

This research was conducted to determine the effects of Phanerochaete chrysosporium inoculation on the ammonia-oxidizing bacterial (AOB) communities during agricultural waste composting. AOB communities with different inoculation regimes were investigated by quantitative PCR and denaturing gradient gel electrophoresis. Results showed that P. chrysosporium inoculation imposed certain stimulatory effects on the AOB amoA gene abundance. Samples with different inoculation regimes were dominated by different AOB species. Linear regression analysis indicated that the AOB community abundance had a significant positive correlation with pile pH (P < 0.05). The AOB amoA gene structure was best related to water soluble carbon (WSC) (P = 0.002, F = 14.17) and pile temperature (P = 0.04, F = 2.72). Variance partition analysis suggested that the sample property heterogeneity induced by inoculation imposed a greater impact (42.9%, P = 0.006) on the bacterial amoA gene structure than different inoculation regimes (23.6%, P = 0.022).

In this study, the effect of reduced hydrogen partial pressure (PH2) on the generation of carboxylic acids from acidogenic fermentation of glucose was investigated. Three strategies were applied to reduce PH2: headspace removal (T1), CO2 sparging (T2) and H2:CO2 (80:20) sparging (T3). Results showed that the production of carboxylic acids in T1-T3 were 10.21, 11.64 and 12.71g/L, respectively, which were 1.04, 1.19 and 1.30-fold of that in the control (T4). The composition of carboxylic acids changed significantly in T3 with enhancement of homoacetogenesis, as more acetate and butyrate were produced comparing to the control. In addition, decreasing PH2 led to more carbon flow to carboxylic acids. Species of Clostridium became dominant in treatment T3, resulting in the shift of metabolic pathways. This study demonstrated that decreasing PH2 could increase the production of carboxylic acids, especially under the strategy of enhancing homoacetogenesis.

The performance and microbial community structure of anaerobic dynamic membrane bioreactor (AnDMBR) treating textile wastewater was investigated. The reactor showed excellent soluble COD and color removal of 98.5% and97.5%, respectively. Dynamic membrane layer grown over the 3D printed dynamic membrane support showed decent rejection for high molecular weight compounds (20 kDa); and the total suspended solid rejection by the dynamic layer was98.8%. Gel permeation chromatography analysis of extracellular polymeric substance (EPS) and effluent samples revealed EPS accounted for more than 76.7% of low molecular weight fractions (20 kDa) that end up in the effluent. Higher applied flux facilitated the rapid formation dynamic layer which enabled a satisfactory effluent quality. Microbial community analysis revealed that during the operation the archaeal community was relatively stable while obvious changes took place in the bacterial community. Introduction of dye Remazol Brilliant Blue R (RBBR) to the AnDMBR increased the abundances of phyla of Proteobacteria and Spirochaetae whereas fractions of Firmicutes and Euryarchaeota decreased obviously. Furthermore, relative stable abundances of phyla Aminicenantes, Bacteroidetes, Thermotogae and Chloroflexi among the top six phyla detected in the system ensured a healthy anaerobic degradation environment for RBBR wastewater treatment.