The rapid development of modern industries is accompanied with the aggravating water heavy metal pollution, which poses a potential threat to the aquatic environment and the health of local populations. As an efficient and economical adsorbent, biochar demonstrates the adsorption capacity for heavy metal ions and its adsorption capacity is significantly enhanced after modification. Therefore, biochar can effectively mitigate environmental pollution. By reviewing the existing studies, we summarize the modification methods of biochar, compare the advantages and disadvantages of physical, biological, and chemical modification methods, analyze the effects of modification on the adsorption capacity of biochar for heavy metal ions, and expound the modification mechanism of biochar. On this basis, this article puts forward the future research directions of the application of biochar in treating coexisting pollutants, aiming to provide a reference for the application of biochar in the purification of heavy metal-containing wastewater.
Charcoal/chemistry* ; Metals, Heavy ; Adsorption ; Wastewater/chemistry* ; Water Pollutants, Chemical/chemistry* ; Water Purification/methods* ; Heavy Ions ; Waste Disposal, Fluid/methods*

Anaerobic granular sludge (AnGS), a self-immobilized aggregate containing various functional microorganisms, is considered as a promising green process for wastewater treatment. AnGS has the advantages of high volume loading rate, simple process and low excess sludge generation, thus shows great technological and economical potentials. This review systematically summarizes the recent advances of the microbial community structure and function of anaerobic granular sludge, and discusses the factors affecting the formation and stability of anaerobic granular sludge from the perspective of microbiology. Moreover, future research directions of AnGS are prospected. This review is expected to facilitate the research and engineering application of AnGS.
Sewage/chemistry* ; Waste Disposal, Fluid ; Anaerobiosis ; Microbiota ; Water Purification ; Bioreactors/microbiology*

Water eutrophication poses great threats to protection of water environment. Microbial remediation of water eutrophication has shown high efficiency, low consumption and no secondary pollution, thus becoming an important approach for ecological remediation. In recent years, researches on denitrifying phosphate accumulating organisms and their application in wastewater treatment processes have received increasing attention. Different from the traditional nitrogen and phosphorus removal process conducted by denitrifying bacteria and phosphate accumulating organisms, the denitrifying phosphate accumulating organisms can simultaneously remove nitrogen and phosphorus under alternated anaerobic and anoxic/aerobic conditions. It is worth noting that microorganisms capable of simultaneously removing nitrogen and phosphorus absolutely under aerobic conditions have been reported in recent years, but the mechanisms remain unclear. This review summarizes the species and characteristics of denitrifying phosphate accumulating organisms and the microorganisms capable of performing simultaneous nitrification-denitrification and phosphorous removal. Moreover, this review analyzes the relationship between nitrogen removal and phosphorus removal and the underlying mechanisms, discusses the challenges of denitrifying phosphorus removal, and prospects future research directions, with the aim to facilitate process improvement of denitrifying phosphate accumulating organisms.
Phosphorus ; Phosphates ; Wastewater ; Denitrification ; Waste Disposal, Fluid ; Nitrogen ; Bioreactors/microbiology* ; Nitrification ; Sewage

The wide use of ZnO and CuO nanoparticles in research, medicine, industry, and other fields has raised concerns about their biosafety. It is therefore unavoidable to be discharged into the sewage treatment system. Due to the unique physical and chemical properties of ZnO NPs and CuO NPs, it may be toxic to the members of the microbial community and their growth and metabolism, which in turn affects the stable operation of sewage nitrogen removal. This study summarizes the toxicity mechanism of two typical metal oxide nanoparticles (ZnO NPs and CuO NPs) to nitrogen removal microorganisms in sewage treatment systems. Furthermore, the factors affecting the cytotoxicity of metal oxide nanoparticles (MONPs) are summarized. This review aims to provide a theoretical basis and support for the future mitigating and emergent treatment of the adverse effects of nanoparticles on sewage treatment systems.
Wastewater/toxicity* ; Sewage/chemistry* ; Zinc Oxide/chemistry* ; Waste Disposal, Fluid ; Nanoparticles/chemistry* ; Metal Nanoparticles/chemistry* ; Nitrogen/metabolism* ; Water Purification

Aims: The primary aim of this study was to utilize abundant palm oil mill effluent (POME) waste and turn it into a value-added product of biomass fuel with high calorific energy value (CEV) via fermentation and drying process, then simultaneously reduce abundant liquid waste. Methodology and results: POME is available abundantly in Malaysia and only a small portion of it is utilized to produce other value-added products. In this study, fermentation of POME in the presence of bacteria (Lysinibacillus sp.) and fungus (Aspergillus flavus) separately at 37 °C, 180 rpm for 5 days, followed by overnight oven-drying at 85 °C was conducted. Four fermentation medium conditions were performed, viz.: (1) autoclaved POME, (2) autoclaved POME with the addition of Lysinibacillus sp., (3) autoclaved POME with the addition of A. flavus and (4) POME as it is (non-sterile). Conclusion, significance and impact of study Among all conditions, fermentation utilizing autoclaved POME in the presence of A. flavus evinced the highest CEV of 25.18 MJ/kg. The fermentation in the presence of Lysinibacillus sp. strain revealed high COD and BOD removal efficiency of 59.20% and 320.44 mg/L as well as the highest reduction of oils and grease among other groups with the value of 15.84%. Future research directions are proposed for the elucidation of co-fermentation in the presence of both Lysinibacillus sp. and A. flavus.
Palm Oil ; Biomass ; Biofuels ; Waste Disposal, Fluid

In order to explore the microbial communities and functions of activated sludge in an Anaerobic-anoxic-oxic (A²/O) process under the start-up of Actinic reaction enzyme system (ARES) system and to understand the impact of the ARES system in domestic sewage treatment process, the activated sludge microbial community structure in the A²/O process system before and after ARES system start-up was analyzed by Illumina-HiSeq 2000 high-throughput sequencing platform. By combining with the main parameters related to the effect of sewage treatment, we analyzed the environmental functions of the microbial communities. The microbial community structure of activated sludge was significantly different before and after the ARES system start-up. There were 9 main bacterial phyla in the system (average relative abundance ≥1%), accounting for 96%-98% of the total bacteria sequenced. After the ARES system was started, the relative abundance of Betaproteobacteria and Chlorobi increased by 3.45%-3.85% and 0.45%-2.61%, respectively. In the anaerobic unit, the relative abundance of Bacteroidetes increased by 12.97%, while the Actinobacteria and Firmicutes decreased by 9.60% and 1.45%, respectively. At the genus level of bacteria, the relative abundance of Denitratisoma increased by 0.80%-3.27%, while the Haliangium and Arcobacter decreased by 3.36%-4.52% and 1.48%-3.45%, respectively. The relative abundance of bacteria was significantly different before and after the ARES system start-up. There were 7 abundant fungi phyla (average relative abundance ≥1%) in the system. After the ARES system was started, the relative abundance of Rozellomycota decreased by 42.71%-46.77%. In the anaerobic unit, the relative abundance of Ascomycota decreased by 13.39%, while the relative abundance of Glomeromycota increased by 13.86%. At the genus level of fungi. The relative abundance of Entomophthoraceae sp. and Glomcromycota sp. increased by 31.35%-36.50% and 6.27%-13.84%, respectively, while the Rozellomycota sp. and Xylochrysis lucida decreased by 42.71%-46.77% and 3.67%-5.54%, respectively. Our results showed that the application of ARES system caused the response of the microbial community to environmental changes, especially for the fungi communities, in the meanwhile, improved the effluent quality, especially the removal rate of total nitrogen.
Anaerobiosis ; Ascomycota ; Bioreactors ; Microbiota ; Nitrogen ; Sewage ; Waste Disposal, Fluid

BACKGROUND: Currently, it is recognized that water polluted with toxic heavy metal ions may cause serious effects on human health. Therefore, the development of new materials for effective removal of heavy metal ions from water is still a widely important area. Melanin is being considered as a potential material for removal of heavy metal from water. METHODS: In this study, we synthesized two melanin-embedded beads from two different melanin powder sources and named IMB (Isolated Melanin Bead originated from squid ink sac) and CMB (Commercial Melanin Bead originated from sesame seeds). These beads were of globular shape and 2-3 mm in diameter. We investigated and compared the sorption abilities of these two bead materials toward hexavalent-chromium (Cr) in water. The isotherm sorption curves were established using Langmuir and Freundlich models in the optimized conditions of pH, sorption time, solid/liquid ratio, and initial concentration of Cr. The FITR analysis was also carried out to show the differences in surface properties of these two beads. RESULTS: The optimized conditions for isotherm sorption of Cr on IMB/CMB were set at pH values of 2/2, sorption times of 90/300 min, and solid-liquid ratios of 10/20 mg/mL. The maximum sorption capacities calculated based on the Langmuir model were 19.60 and 6.24 for IMB and CMB, respectively. However, the adsorption kinetic of Cr on the beads fitted the Freundlich model with R values of 0.992 for IMB and 0.989 for CMB. The deduced Freundlich constant, 1/n, in the range of 0.2-0.8 indicated that these beads are good adsorption materials. In addition, structure analysis data revealed great differences in physical and chemical properties between IMB and CMB. Interestingly, FTIR analysis results showed strong signals of -OH (3295.35 cm) and -C=O (1608.63 cm) groups harboring on the IMB but not CMB. Moreover, loading of Cr on the IMB caused a shift of broad peaks from 3295.35 cm and 1608.63 cm to 3354.21 cm and 1597.06 cm, respectively, due to -OH and -C=O stretching. CONCLUSIONS Taken together, our study suggests that IMB has great potential as a bead material for the elimination of Cr from aqueous solutions and may be highly useful for water treatment applications.
Adsorption ; Chromium ; chemistry ; Kinetics ; Melanins ; chemistry ; Waste Disposal, Fluid ; methods ; Water Pollutants, Chemical ; chemistry ; Water Pollution, Chemical ; prevention & control ; Water Purification ; methods

The effects of two different external carbon sources (acetate and ethanol) and electron acceptors (dissolved oxygen, nitrate, and nitrite) were investigated under aerobic and anoxic conditions with non-acclimated process biomass from a full-scale biological nutrient removal-activated sludge system. When acetate was added as an external carbon source, phosphate release was observed even in the presence of electron acceptors. The release rates were 1.7, 7.8, and 3.5 mg P/(g MLVSS·h) (MLVSS: mixed liquor volatile suspended solids), respectively, for dissolved oxygen, nitrate, and nitrite. In the case of ethanol, no phosphate release was observed in the presence of electron acceptors. Results of the experiments with nitrite showed that approximately 25 mg NO₂-N/L of nitrite inhibited anoxic phosphorus uptake regardless of the concentration of the tested external carbon sources. Furthermore, higher denitrification rates were obtained with acetate (1.4 and 0.8 mg N/(g MLVSS·h)) compared to ethanol (1.1 and 0.7 mg N/ (g MLVSS·h)) for both anoxic electron acceptors (nitrate and nitrite).
Biomass ; Bioreactors ; Carbon/chemistry* ; Denitrification ; Electrons ; Nitrates ; Nitrites ; Oxygen ; Phosphates ; Phosphorus/chemistry* ; Sewage ; Waste Disposal, Fluid/methods* ; Wastewater ; Water Pollutants, Chemical ; Water Purification/methods*

In order to broaden the application area of the new nitrogen removal technology, a full-scale system for short-cut nitrification and anaerobic ammonium oxidation (Anammox) was investigated in the nitrogen removal from a strong-ammonium pharmaceutical wastewater. When the influent ammonium concentration was (430.40 ± 55.43) mg/L, ammonia removal efficiency was (81.75 ± 9.10)%. The short-cut nitrification and Anammox system could successfully remove nitrogen from the pharmaceutical wastewater. The start-up of short-cut nitrification system took about 74 d and the nitrite accumulation efficiency was (52.11 ± 9.13)%, the two-step mode using synthetic wastewater and actual wastewater was suitable for the start-up of short-cut nitrification system. The start-up of Anammox system took about 145 d and the maximum volumetric nitrogen removal rate was 6.35 kg N/(m3·d), dozens of times higher than those for the conventional nitrification-denitrification process. The strategy achieving Anammox sludge by self-growth and biocatalyst addition was suitable for the start-up of Anammox system.
Ammonia ; chemistry ; Bioreactors ; Drug Industry ; Nitrification ; Nitrites ; chemistry ; Nitrogen ; chemistry ; Sewage ; microbiology ; Waste Disposal, Fluid ; methods ; Waste Water ; chemistry

The anaerobic granular sludge from an Internal Circulation (IC) reactor of a paper mill wastewater treatment plant were seeded in an Anammox upflow anaerobic sludge blanket reactor. After 185 days operation, the reactor was finally started up by increasing the influent ammonium and nitrite concentrations to 224 mg/L and 255 mg/L, respectively, with volumetric nitrogen removal rate increasing to 3.76 kg/(m3·d). The physicochemical characteristics of the cultivated Anammox granules were observed by scanning electron microscope, transmission electron microscope and Fourier Transform infrared spectroscopy (FTIR). Results suggested that during the start-up course, the granular sludge initially disintegrated and then re-aggregated. FTIR spectra results revealed that the Anammox granular sludge contained abundant functional groups, indicating that it may also possess good adsorption properties. The ecological structure of the granular sludge, analyzed by the metagenomic sequencing methods, suggested that the relative abundance of the dominant bacterial community in the seeding sludge, i.e., Proteobacteria, Firmicutes, Bacteroidetes, significantly reduced, while Planctomycetes which contains anaerobic ammonium oxidation bacteria remarkably increased from 1.59% to 23.24% in the Anammox granules.
Ammonia ; chemistry ; Bacteria ; Bioreactors ; Nitrogen ; chemistry ; Sewage ; microbiology ; Waste Disposal, Fluid ; methods ; Waste Water ; chemistry