Treatment Of Coal Wastewater Research Articles

Preparation and application of low-cost fibers for efficient adsorption of oil from coal pyrolysis wastewater and establishment of quantitative equation for calculating oil contact angle under water

The removal of oil from coal pyrolysis wastewater persists to be a challenging problem. Thus, this study proposes a new scheme that integrates the adsorption of oil using fibers and subsequent centrifugation or elution to achieve efficient oil–water separation. Based on their stable chemical property, PP and were selected as the substrates for drawing the fibers. In addition, PVDF and PTFE were explored to modify the wettability of PP and PE. The performances of as-prepared fibers were tested for removing oil from wastewater in both batch and continuous modes. Among all the fibers, the PVDF-modified PP fibers exhibited the best performance. For PP-based fibers with 5 wt% PVDF, the saturated oil-removal efficiency reached 92.24 % in case of the simulated wastewater and 81.10 % for the actual wastewater. Given that the oil content in coal pyrolysis wastewater was ~2000 ppm, the residual oil content in the outlet water would be ~380 ppm, which satisfies the requirement of the subsequent treatment process. Furthermore, the PVDF-modified PP fibers exhibited excellent reusability and stability to defy various environmental corrosions. The separation of oil and water based on the adsorption by fibers offers promising prospect to remove oil from coal pyrolysis wastewater. In addition, we derived a formula to calculate the oil contact angle under water based on Young's equation using several measurable parameters. As the calculation results were consistent with real scenarios, this derived formula can provide quantitative guidance for material modification in coal wastewater treatment.

The Synergistic Effects of Al3+ and Chitosan on the Solid-Liquid Separation of Coal Wastewater and Their Mechanism of Action.

It is important to identify an environmentally friendly and efficient flocculant that can replace polyacrylamide for the solid–liquid separation of coal wastewater. In this study, to explore whether chitosan can be used as an environmentally friendly and efficient flocculant for the solid–liquid separation of coal wastewater, AlCl3–chitosan was used to conduct flocculation–sedimentation and dewatering tests under different chitosan dosages and shear-strength conditions for the prepared coal wastewater. Focused beam reflectance was measured to dynamically monitor the number of refractory fine particles, and the settled flocs were photographed and analyzed with microscopy to explore the effect of AlCl3–chitosan on the flocculation settlement effect and floc characteristics. The synergistic mechanisms of AlCl3 and chitosan were investigated using quartz crystal dissipative microbalance and zeta potential measurement. The results showed that the addition of chitosan can significantly improve the flocculation–sedimentation and dewatering effects of coal wastewater. A reasonable dosage under a certain shear strength is conducive to the reduction of fine slime particles, which results in a compact floc structure, increases the floc size, and improves the settling effect. The synergistic effect of AlCl3–chitosan improved the electric neutralization and adsorption bridging abilities of the chitosan, and the mixed solution of AlCl3 and chitosan had stronger adsorption on the carbon surface. This study provides a new approach to the selection of flocculants for coal wastewater treatment.

Assessing the environmental performance of a novel coal mine brine treatment technique: A case in Poland

Although the energy transition results in decreased use of coal for power production, hard coal extraction will continue due to its importance in steel production and coal mine wastewater will continue generating after mines closure. The coal mining sector produces wastewater which results in environmental burdens and often contains valuable materials that can be treated to eliminate effluent discharge and recover contained materials. The aim of this study is to determine whether the implementation of a novel wastewater treatment technique in an existing coal wastewater treatment plant (WWTP) can improve both environmental performance and resource recovery potential. Our study assesses for the first time the environmental performance of the WWTP of Dębieńsko at the Upper Silesian Coal Basin, in Poland because coal mine effluents need to be treated to eliminate current environmental impacts on surface water bodies (rivers). The existing wastewater treatment system comprises reverse osmosis, evaporation and crystallization technologies. In the case of the novel ZERO BRINE technique, lab performance data is scaled-up and used for nanofiltration, reverse osmosis, electrodialysis and crystallization technologies. The environmental impacts analysis is performed with life cycle assessment (LCA) by considering mid-point impact categories (climate change, terrestrial acidification and fossil resource scarcity) and end-point damages (human health, ecosystems and resources). The functional unit is 1 m3 of coal mine wastewater input and a scenario is developed where the plant functionality concerns salt production. Results show that the implementation of the ZERO BRINE technique can improve the environmental performance of the WWTP for all considered impact categories due to a reduction in electricity consumption by 13% in the entire plant. Climate change, acidification, fossil resources scarcity, human health, ecosystems, and resources were improved by 16%, 13%, 12%, 25%, 21% and 13%, respectively. A sensitivity analysis is performed on the electricity consumption of electrodialysis which shows an additional improvement by 7% on all impacts. The ZERO BRINE technique produces both water and different types of salts. In this case, the multi-functionality of the system is addressed through substitution, while sensitivity analyses are carried out using mass and economic allocation methods.

Modification of Cu2+ in polyphenol oxidase extract from purple eggplant for phenol degradation in coal wastewater treatment

Cracking coal-forming organic compounds during the gasification process produces liquid waste containing phenolic compounds that require special handling based on their toxicity. As one of the components, there is liquid waste resulting from the coal gasification process. The purpose of this research was to study the activity of polyphenol oxidase (PPO) on phenol after the addition of Cu2+ to purple eggplant (Solanum melongena L.) extract and its potential to work more effectively in phenol biodegradation for coal wastewater containing phenol. Enzyme activity and phenol determination were carried out spectrophotometrically. The results showed PPO activity of 25.90-38.10 U/mL; 4.0 mM phenol and the activity of PPO-Cu2+ was 21.58-46.32 U/mL; 2-10 mM CuSO4; 2.0-4.0 mM phenol. Based on Michaelis Menten’s graph, the initial rate of PPO-Cu2+ was 0.015 mM/min and the initial rate of PPO was 0.15 mM/min using 2 mM phenol as a substrate. Lineweaver-Burk’s graph shows the KM of PPO-Cu2+ = 6.92 mM, which is lower than KM of PPO = 13.05 mM. Its means that the phenol response has a higher affinity for PPO-Cu2+ than PPO. The application of PPO-Cu2+ in purple eggplant extract works effectively as much as 46.7% for artificial coal liquid waste containing phenol.

Comparing the effectiveness of chitosan and conventional coagulants for coal wastewater treatment

In this research, the potential of chitosan to be used as a coagulant to treat coal wastewater was investigated, in comparison to a conventional coagulant, i.e: Al2(SO4)3 or aluminum sulfate, and Poly Aluminium Chloride (PAC). The parameters being studied were turbidity, pH, TDS, and TSS. The result of this research showed that chitosan worked as a more efficient coagulant to treat coal wastewater compared to alum and PAC, in terms of the needed dose of application. The optimum dose of chitosan was 20 mg/L that gave a 100% decrease in turbidity and TSS. On the other hand, a dose of 120 mg/L of alum was needed to have an optimum result, where the turbidity and TSS were decreased up to 100%. When PAC was used as a coagulant, the optimum dose was 120 ppm that reduced turbidity and TSS to 99.50% and 99.58%, respectively. Coagulation by chitosan, alum, and PAC were all influenced by pH, where the optimum pH for all three coagulants was within a range of neutral pH.

Application of Membran Polyvinylidenefluoride (PVDF) Synthesis Blending TiO<sub>2</sub>-Serbuk Kelor (Moringa Oleifera) Seed on Coal Wastewater Treatment

Membrane technology is the right choice with its ability as a highly selective separation process to produce high quality products. The technology research applied based on chemical technology of Advanced Oxidation Process (AOP), a technology of coal wastewater treatment using strong oxidizing agents with photocatalysts TiO₂ and moringa seed powder (Moringa oleifera). The research methodology used was preparation of Moringa seeds, synthesis of composite photocatalyst TiO₂-Moringa seed powder and manufacture of membrane Polyinylideneflouride (PVDF)-Moringa seed powder with a total of 4 membranes (A, B, C, D). The results of the study produced membrane characteristics with a pore size of 0,1 μm - 6 μm, wet weight of 20% and an average tensile test value of 4.53 N/mm2. Application of membrane PVDF-synthesis TiO₂-Moringa seed powder (Moringa oleifera) in coal wastewater treatment resulted in a decrease of 89% in Fe and Mn pollutants in the composition of 5% TiO₂ and 5% Moringa seed powder in Membrane B.

The synthetic activities of TiO2-moringa oleifera seed powder in the treatment of the wastewater of the coal mining industry

To process the coal wastewater, the combination of chemical based technology of Advanced Oxidation Process (AOP) of a strong oxidizer using TiO2 photocatalyst and biological treatment of moringa seed powder (Moringa oleifera) is used in the composite form. AOP can be used as an alternative treatment of coal wastewater which is quite economical and environmentally friendly. The XRD results of TiO2 powder and the synthesis of TiO2 - is moringa seed powder in the form of tetragonal crystals. The degradation results of the quality of the coal wastewater using TiO2 powder reached a decrease of (TSS, Fe, Mn, Zn, Hg, Cu, Co, Cr, Al and Ni) by an average of 70% and the increase of pH value of 7 at 200 minute stirring time. The decrease of the wastewater quality using the synthesis of TiO2- moringa seed powder by using sunlight and without sunlight is detected negative (-) at 200 minute stirring time.

Study on bubble column humidification and dehumidification system for coal mine wastewater treatment.

Water is important resource for human survival and development. Coal mine wastewater (CMW) is a byproduct of the process of coal mining, which is about 7.0 × 1010 m3 in China in 2016. Considering coal mine wastewater includes different ingredients, a new bubble column humidification and dehumidification system is proposed for CMW treatment. The system is mainly composed of a bubble column humidification and dehumidification unit, solar collector, fan and water tank, in which air is used as a circulating medium. The system can avoid water treatment component blocking for reverse osmosis (RO) and multi effect distillation (MED) dealing with CMW, and produce water greenly. By analysis of heat and mass transfer, the effects of solar radiation, air bubble velocity and mine water temperature on water treatment production characteristics are studied. Compared with other methods, thermal energy consumption (TEC) of bubble column humidification and dehumidification (BCHD) is moderate, which is about 700 kJ/kg (powered by solar energy). The results would provide a new method for CMW treatment and insights into the efficient coal wastewater treatment, besides, it helps to identify the parameters for the technology development in mine water treatment.

Effect of COD/NO 3−-N ratio on the performance of a hybrid UASB reactor treating phenolic wastewater

The effect of COD/O 3 −-N ratio on the biodegradation of complex phenolic mixture was studied in bench scale hybrid upflow anaerobic sludge blanket (HUASB) reactors. HUASB reactor is a combination of a UASB unit at the lower part and an anaerobic fixed film at the upper end. The aim of this study was to evaluate the biodegradability of phenolic mixture (from synthetic coal wastewater) as the only carbon and energy source in continuous experiments using nitrate as the final electron acceptor. Synthetic coal wastewater contained phenol (490 mg/L); m-, o-, p-cresols (123.0 mg/L, 58.6 mg/L, 42 mg/L); 2,4-, 2,5-, 3,4- and 3,5 dimethyl phenols (6.3 mg/L, 6.3 mg/L, 4.4 mg/L and 21.3 mg/L) as major phenolic compounds representing the complex phenolic mixture. Nitrate nitrogen loading was increased from 0.11 g/m 3/d to 0.5 g/m 3/d in order to keep COD/NO 3 −-N ratio as 20.1, 14.85, 9.9, 6.36 and 4.45. An input phenolics concentration of 752 mg/L and hydraulic retention time (HRT) of 24 h was maintained through out the study. Removal of phenolic mixture was found to increase with the lowering of COD/NO 3 −-N ratio. Maximum phenolics removal of 98% was achieved at a COD/NO 3 −-N ratio of 6.36. However, phenolics removal got adversely affected when COD/NO 3 −-N ratio was reduced below 6.36. A nitrogen production efficiency of 78% was obtained according to nitrate consumption. Simultaneous denitrification and methanogenesis was observed in all the reactors throughout the study, demonstrating that denitrification is a feasible alternative for the treatment of coal wastewater. Granules degrading complex phenolic mixture were of diameter 1.6–2.25 mm.

Remediation of phenol-contaminated soil by a bacterial consortium and Acinetobacter calcoaceticus isolated from an industrial wastewater treatment plant

Time-course performance of a phenol-degrading indigenous bacterial consortium, and of Acinetobacter calcoaceticus var. anitratus, isolated from an industrial coal wastewater treatment plant was evaluated. This bacterial consortium was able to survive in the presence of phenol concentrations as high as 1200 mg L −1 and the consortium was more fast in degrading phenol than a pure culture of the A. calcoaceticus strain. In a batch system, 86% of phenol biodegradation occurred in around 30 h at pH 6.0, while at pH 3.0, 95.2% of phenol biodegradation occurred in 8 h. A high phenol biodegradation (above 95%) by the mixed culture in a bioreactor was obtained in both continuous and batch systems, but when test was carried out in coke gasification wastewater, no biodegradation was observed after 10 days at pH 9–11 for both pure strain or the isolated consortium. An activated sludge with the same bacterial consortium characterized above was mixed with a textile sludge-contaminated soil with a phenol concentration of 19.48 mg kg −1. After 20 days of bioaugmentation, the remanescent phenol concentration of the sludge-soil matrix was 1.13 mg kg −1.