Haifeng Zhuang

Short CommunicationAdvanced treatment of biologically pretreated coal gasification wastewater by a novel integration of heterogeneous catalytic ozonation and biological process

Advanced treatment of biologically pretreated coal gasification wastewater (CGW) was investigated employing heterogeneous catalytic ozonation integrated with anoxic moving bed biofilm reactor (ANMBBR) and biological aerated filter (BAF) process. The results indicated that catalytic ozonation with the prepared catalyst (i.e. MnOx/SBAC, sewage sludge was converted into sludge based activated carbon (SBAC) which loaded manganese oxides) significantly enhanced performance of pollutants removal by generated hydroxyl radicals. The effluent of catalytic ozonation process was more biodegradable and less toxic than that in ozonation alone. Meanwhile, ANMBBR-BAF showed efficient capacity of pollutants removal in treatment of the effluent of catalytic ozonation at a shorter reaction time, allowing the discharge limits to be met. Therefore, the integrated process with efficient, economical and sustainable advantages was suitable for advanced treatment of real biologically pretreated CGW.

Advanced treatment of biologically pretreated coal gasification wastewater using a novel expansive flow biological intermittent aerated filter process with a ceramic filler from reused coal fly ash

A novel expansive flow biological intermittent aerated filter (BIAF) process was employed for the advanced treatment of real biologically pretreated coal gasification wastewater (CGW) which had poor biodegradability and a low carbon/nitrogen ratio. The results indicated that the expansive flow BIAF with reused coal fly ash and clay as a ceramic filler exhibited efficient performance for pollutant removal. The effluent concentrations of COD, total phenols, NH4+-N, and total nitrogen (TN), were 39.5, 4.8, 6.3, and 18.8 mg L−1 respectively, with a turbidity of 3 NTU and chromaticity of 26 degrees at the optimal hydraulic retention time of 9 h, meeting the standards for the reuse of water. Moreover, most toxic and refractory pollutants were also eliminated. Meanwhile, intermittent aeration not only significantly increased nitrate and nitrite reductases, but also successfully improved simultaneous nitrification and denitrification activity which facilitated TN removal. The results of high-throughput sequencing represented that the biological process included 28 major bacteria which were affiliated to 7 phyla, where Thermomonas, Methylococcus and Comamona were the most important functional genera. After stable operation for 192 h, the optimal backwashing time was 6 min when the air and water intensities were 8 and 2.5 L (s m2)−1, respectively. These results demonstrated that the expansive flow BIAF process, with the advantages of efficient, economical and sustainable development, was beneficial to engineering applications.

Adsorption and bioregeneration in the treatment of phenol, indole, and mixture with activated carbon

AbstractThe study aims to: (1) investigate the adsorption of powdered activated carbon (PAC) and granular activated carbon (GAC) for phenol, indole, and their mixtures, respectively, and (2) determine the bioregeneration efficiency and reusability of PAC loaded with phenol, indole, and their mixtures. The results showed that phenol was easier to be adsorbed than indole. The adsorption using PAC was obviously better than GAC. The considerably higher bioregeneration efficiency of the phenol-loaded PAC as compared to that of indole-loaded PAC was probably due to the recalcitrant nature of indole. PAC exhibited much higher adsorption capacity for indole, especially in the presence of low concentration of phenol. Besides, phenol improved the biodegradation of indole and therefore enhanced the reusability of indole-loaded PAC. Therefore, powdered activated carbon technology (PACT) was appropriate for the treatment of similar wastewater. Within the PACT system, PAC preferentially adsorbed the recalcitrant indole...

Effect of pure oxygen fine bubbles on the organic matter removal and bacterial community evolution treating coal gasification wastewater by membrane bioreactor

A lab-scale study was investigated to evaluate the effect of pure oxygen fine bubbles on membrane bioreactor (O2-MBR) performance of treating coal gasification wastewater. Compared with conventional MBR using aeration source of air (CMBR), the removal efficiencies of COD and total phenols increased by 28% and 36%, and the organic compositions of treated effluent represented significant difference that was mainly attributed to the controlled the foam expansion and enhanced the enzymatic activities in O2-MBR. Moreover, membrane fouling mitigation was observed in O2-MBR, probably owing to the less EPS amount and larger PSD. It was notable that the pure oxygen with fine bubbles promoted marked evolution of bacterial community from CMBR to O2-MBR, particularly, the bacterial community richness and diversity in O2-MBR was lower than CMBR, and the genera Phycisphaera, Comamonas, Thauera and Ohtaekwangia composed the top four most relative abundance genera in O2-MBR, giving the total relative abundance of 26.7%.

Simultaneous removal of organic matter and salt ions from coal gasification wastewater RO concentrate and microorganisms succession in a MBR

A lab-scale membrane bioreactor (MBR) with intermittent aeration was operated to treat the reverse osmosis concentrate derived from coal gasification wastewater. Results showed intermittent aeration represented slight effect on organic matter reduction but significant effect on nitrite and nitrate reduction, with 6h aeration and 6h non-aeration, removal efficiencies of organic matter, chloride, sulfate, nitrite and nitrate reached 48.35%, 40.91%, 34.28%, -36.05% and 64.34%, respectively. High-throughput sequencing showed a microorganisms succession from inoculated activated sludge (S1) to activated sludge in MBR (S2) with high salinity. Richness and diversity of microorganisms in S2 was lower than S1 and the community structure of S1 exhibited more even than S2. The most relative abundance of genus in S1 and S2 were unclassified_Desulfarculaceae (9.39%) and Roseibaca (62.1%), respectively. High salinity and intermittent aeration represented different influence on the denitrifying genus, and non-aeration phase provided feasible dissolved oxygen condition for denitrifying genera realizing denitrification.

Recycling rice straw derived, activated carbon supported, nanoscaled Fe3O4 as a highly efficient catalyst for Fenton oxidation of real coal gasification wastewater

Recycled rice straw was converted into an activated carbon support for nanoscaled Fe3O4. The resulting catalyst (Fe3O4MNPs/RSAC) was then evaluated for its effectiveness in the treatment of real coal gasification wastewater (CGW), which contained strong toxins and refractory pollutants that were poorly biodegradable. The results indicated that Fenton oxidation with the prepared catalyst was a highly efficient means of treatment for CGW over a wide pH range: the corresponding COD, cyanide and total phenols (TPh) removal efficiencies were 55.5, 46.5 and 85.5%, respectively. The treated wastewater was more biodegradable and less toxic, which aided in subsequent processing. The efficiency enhancement was attributed to the generation of more hydroxyl radicals and a possible reaction mechanism was proposed. Furthermore, Fe3O4MNPs/RSAC showed superior stability over ten successive runs. Moreover, heterogeneous Fenton oxidation by Fe3O4MNPs/RSAC also enhanced the aerobic biodegradation of CGW. Overall, 92.9% of COD and 98.5% of TPh were removed via the integration of Fenton oxidation and biological processing. Thus, the catalysis of Fenton oxidation by Fe3O4MNPs/RSAC was efficient, cost-effective and sustainable with a beneficial engineering application in the treatment of refractory wastewater, and a new and sustainable use for waste rice straw.

Potential enhancement of direct interspecies electron transfer for anaerobic degradation of coal gasification wastewater using up-flow anaerobic sludge blanket (UASB) with nitrogen doped sewage sludge carbon assisted

Waste sewage sludge was converted into the novel conductive material of nitrogen doped sewage sludge carbon (N-SC) to enhance anaerobic degradation of coal gasification wastewater (CGW). The results indicated that N-SC played a significant role in enhanced efficiencies, with chemical oxygen demand (COD) removal efficiency increased by 25.4%, methane production rate improved by 68.1% and total volatile fatty acids (VFA) decreased by 37.5% than that of controlled reactor. The conductivity, activity of electron transport, and extracellular polymeric substances (EPS) of anaerobic sludge were remarkably enhanced with N-SC, which promoted sludge granulation and supplied better conductive environment for microorganisms. The microbial community analysis revealed that potential enhancement of direct interspecies electron transfer (DIET) was achieved by electrical connection between enriched Geobacter, Pseudomonas and Methanosaeta with N-SC assisted, which enhanced the anaerobic degradation of CGW. Moreover, anaerobic degradation with N-SC had higher capacity to resist acidic shocks, facilitating the process stability.

New insights into enhanced anaerobic degradation of Fischer-Tropsch wastewater with the assistance of magnetite

In this study, magnetite (Fe3O4), as the typical conductive material, was supplemented in anaerobic sequential batch reactor (ASBR) with the attempt to enhance pollutants removal and methane production during Fischer-Tropsch wastewater treatment. The results showed that COD removal efficiency and cumulative methane production with the addition of optimum magnetite dosage (0.4 g) were as high as 84.3 ± 2.0% and 7.46 ± 0.24 L, which were higher than other test groups (0, 0.2 and 0.6 g). Furthermore, the combination of high-throughput 16S rRNA gene pyrosequencing and metagenomic analysis in this study further confirmed that the Geobacter and Methanosaeta species were specially enriched in bacterial and archaeal community at the optimum magnetite dosage, suggesting that magnetite-mediated direct interspecies electron transfer (DIET) between Geobacter and Methanosaeta species was likely a crucial reason to promote syntrophic metabolism of propionic acid and butyric acid, and further enhance final methanogenesis.

Influence of interfering anions on Cu2+ and Zn2+ ions removal on chestnut outer shell-derived hydrochars in aqueous solution

Hydrothermal carbonization method was used to produce different hydrochars from chestnut outer shell at various temperatures while resolving the environmental issues of agricultural bio-waste. Hydrochars were adopted as adsorbents to remove heavy metal ions (copper and zinc ions) from aqueous solution. Hydrochar samples were characterized by Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR), and Brunauer–Emmett–Teller (BET) nitrogen adsorption–desorption isotherm. An increase in the hydrothermal temperature from 160 °C to 220 °C results in higher BET surface area (18.81 m2 g−1) and the porosity of the samples. The resultant hydrochar at 220 °C exhibited a more excellent adsorption performance (8.13 mg g−1 for copper nitrate) than the other two hydrochars at low hydrothermal temperature. The current study addressed the influence of interfering anions of nitrates, sulfates and chlorides on the adsorption performance. The result shows that the hydrochar possesses larger removal efficiency for heavy metal nitrates that that of chlorides and sulfates.

Waste rice straw and coal fly ash composite as a novel sustainable catalytic particle electrode for strengthening oxidation of azo dyes containing wastewater in electro-Fenton process

A novel catalytic particle electrode (CPE) was synthesized from waste rice straw and coal fly ash which was employed to strengthen electro-Fenton treating actual azo dyes containing wastewater. Results showed that the prepared CPE exhibited excellent electro-catalytic activity and significantly improved performance of pollutants removal at near-neutral pH condition, achieving over 73.5 and 90.5% of chemical oxygen demand (COD) and color removal percentages, respectively, allowing discharge criteria to be met. And the electro-Fenton with CPE improved the biodegradability of wastewater in terms of BOD5/COD, resazurin dehydrogenase activity, and toxicity, indicating the potential application of integrated biosystem for this type of wastewater. On the basis of inhibition of different radical scavengers and fluorescence test, it was deduced that the main contribution of the novel CPE was responsible for catalyzing electro-generate H2O2 to produce more hydroxyl radicals in electro-Fenton, and the positive role of generation of superoxide anion at near-neutral pH was also proved, further the possible reaction mechanism was proposed. Moreover, CPE showed the advantages of superior stability and low cost at successive runs and the results offered new insights for sustainable use of waste materials.