Experimental Research on Coke Wastewater Treatment by Hybrid Biological Reactor

Phase hybrid biological reactor （HBR） was used in treating coke wastewater by adding submerging fiber-ball fillers in suspended growth activated sludge. The optimum operation parameters for the highest performance were determined. It was found that the hybrid biological reactor worked well for the coke wastewater treatment in terms of Chemical Oxygen Demand （COD）, NH4＋ -N and other refractory organic compounds removal efficiencies. Compared with conventional activated sludge system, the removal rate of COD and NH4＋ -N and the nitrating rate were higher and more stable in the hybrid biological reactor. COD of effluent was less than 75 mg/L and the removal rate of COD and NH4＋ -N could be up to 95.0% and 92.5% when COD of influent and NH4＋ -N were less than 700 mg/L and 300 rag/L, respectively. In this way, the quality of effluent concentration could reach the first class of integrated wastewater discharge standard （GB8978-1996） （COD ≤100 mg/L）.

Metagenomic Insight Reveals the Microbial Structure and Function of the Full-Scale Coking Wastewater Treatment System:Gene-Based Nitrogen Removal

Microbial communities play crucial roles in pollutant removal and system stability in biological systems for coking wastewater(CWW)treatment,but a comprehensive understanding of their structure and functions is still lacking.A five month survey of four sequential bioreactors,anoxic 1/oxic 1/anoxic 2/oxic 2(A1/O1/A2/O2),was carried out in a full-scale CWW treatment system in China to elucidate operational performance and microbial ecology.The results showed that A1/O1/A2/O2 had excellent and stable performance for nitrogen removal.Both total nitrogen(TN;(17.38±6.89)mgL1)and ammonium-nitrogen(NH4 t-N;(2.10±1.34)mg·L^(-1))in the final biological effluent satisfied the Chinese national standards for CWW.Integrated analysis of 16S ribosome RNA(rRNA)sequencing and metagenomic sequencing showed that the bacterial communities and metagenomic function profiles of A1 and O1 shared similar functional structures,while those of A2 significantly varied from those of other bioreactors(p<0.05).The results indicated that microbial activity was strongly connected with activated sludge function.Nitrosospira,Nitrosomonas,and SM1A02 were responsible for nitrification during the primary anoxic-oxic(AO)stage and Azoarcus and Thauera acted as important denitrifiers in A2.Nitrogen cycling-related enzymes and genes work in the A1/O1/A2/O2 system.Moreover,the hao genes catalyzing hydroxylamine dehydrogenase(EC 1.7.2.6)and the napA and napB genes catalyzing nitrate reductase(EC 1.9.6.1)played important roles in the nitrification and denitrification processes in the primary and secondary AO stages,respectively.The mixed liquor suspended solids(MLSS)/total solids(TS),TN removal rate(RR),total organic carbon(TOC)(RR),and NH_(4)^(+)t-N(RR)were the most important environmental factors for regulating the structure of core bacterial genera and nitrogen-cycling genes.Proteobacteria were the potential main participants in nitrogen metabolism in the A1/O1/A2/O2 system for CWW treatment.This study provides an original and comprehensive understanding of the microbial community and functions at the gene level,which is crucial for the efficient and stable operation of the full-scale biological process for CWW treatment.

Treatment of coke plant wastewater by SND fixed biofilm hybrid system

In this article, coke plant wastewater was treated by a simultaneous nitrifying and denitrifying （SND） fixed biofilm hybrid system. The results showed that suitable parameters of the system were important for the performance of the bio-degradation system. The chemical oxygen demand （COD） removal efficiency in this system was satisfactory, higher than 94%, and ammonia nitrogen was higher than 95%. The effluent COD concentration could meet the discharge standard, except for very few situations. The results showed that a sufficient carbon source was important for making ammonia nitrogen concentration meet the discharge standard. Then the TiN removal efficiency in this system can be brought higher than 94%. Dissolved oxygen （DO） is very important to the performance of the SND bio-degradation system, and the suitable DO is about 3.5-4.0 mg/L at the forepart of reactor. In addition, the performance of the system was almost not affected by pH value. The results show that the system is feasible to treat coke plant wastewater.

Electrochemical treatment of COD in biologically pretreated coking wastewater using Ti/RuO2-IrO2 electrodes combined with modified coke

The electrochemical treatment of COD contained in biologically pretreated coking wastewater treated by a three-dimensional electrode system with modified coke as the particle electrode was investigated. And the electrochemical perromance of the coke modified with various active components was studied. The results show that the coke modified with Fe（NO3）2 has the lowest energy consumption and higher COD removal rate under the same condition, and the modified coke has better surface characteristics for the purpose of this study. In addition, the kinetic constant was also calculated. The study shows that the three-dimensional electrode system with Fe （NO3）z-modified coke can give a satisfactory solution in biologically pretreated coking wastewater.

Decomposition of Organic Compounds in Coke Plant Wastewater by Ultrasonic Irradiation and Its Combined Process

The paper deals with the degradation of the organic compounds in the coke plant wastewater by the combined process of ultrasonic irradiation and activated sludge. The influence factors of the ultrasonic degradation effect such as air atmosphere, initial concentration, ultrasonic power density and the category and consumption of catalyst were investigated. A water quality model was used to explain the degradation of different kinds of organic compounds in the coke plant wastewater by ultrasonic irradiation. After the wastewater was treated by the combined process of ultrasonic irradiation and activated sludge, the COD degradation efficiency was 95.74%, which is 63.49% higher than that by the process of activated sludge alone.

Pretreatment of coking wastewater using anaerobic sequencing batch reactor (ASBR)

A laboratory-scale anaerobic sequencing batch reactor (ASBR) was used to pretreat coking wastewater. Inoculated anaerobic granular biomass was acclimated for 225 d to the coking wastewater, and then the biochemical methane potential (BMP)of the coking wastewater in the acclimated granular biomass was measured. At the same time, some fundamental technological factors, such as the filling time and the reacting time ratio (tf/tr), the mixing intensity and the intermittent mixing mode, that affect anaerobic pretreatment of coking wastewater with ASBR, were evaluated through orthogonal tests. The COD removal efficiency reached 38％～50％ in the stable operation period with the organic loading rate of 0.37～0.54 kg COD/(m3.d) at the optimum conditions of tf/tr, the mixing intensity and the intermittent mixing mode. In addition, the biodegradability of coking wastewater distinctly increased after the pretreatment using ASBR. At the end of the experiment, the microorganism forms on the granulated sludge in the ASBR were observed using SEM (scanning electron microscope) and fluoroscope. The results showed that the dominant microorganism on the granular sludge was Methanosaeta instead of Methanosarcina dominated on the inoculated sludge.

The Kinetics for Electrochemical Removal of Ammonia in Coking Wastewater

Electrochemical removal of ammonia is a new and effective method in coking wastewater.The reaction mechanism of ammonia removal was proved by stable polarization curve in this paper.First,the supposing of reaction steps of the electrode were proposed.And then reaction parameter of the electrode was measured by Tafel curve.Finally,the reaction mechanism was determined by quasi-equilibrium approach.The results showed that Cl2+H2O→HOCl+H++Cl was the rate-determining step,the calculated apparent transfer coefficient was uniform to the experimental value.

Advanced treatment of biologically pretreated coking wastewater by intensified zero-valent iron process(IZVI) combined with anaerobic filter and biological aerated filter(AF/BAF)

Experiments were conducted to investigate the behavior of the sequential system of intensified zero-valent iron process(IZVI) and anaerobic filter and biological aerated filter(AF/BAF) reactors for advanced treatment of biologically pretreated coking wastewater. Particular attention was paid to the performance of the integrated system for the removal of chemical oxygen demand(COD), ammonia nitrogen(NH3-N) and total nitrogen(TN). The average removal efficiencies of COD, NH3-N and TN were 76.28%, 96.76% and 59.97%, with the average effluent mass concentrations of 56, 0.53 and 18.83 mg/L, respectively, reaching the first grade of the national discharge standard. Moreover, the results of gas chromatography/mass spectrum(GC/MS) and gel permeation chromatography(GPC) analysis demonstrated that the refractory organic compounds with high relative molecular mass were partly removed in IZVI process by the function of oxidation-reduction, flocculation and adsorption which could also enhance the biodegradability of the system effluent. The removal efficiencies of NH3-N and TN were achieved mainly in the subsequent AF/BAF reactors by nitrification and denitrification. Overall, the results obtained show that the application of IZVI in combination with AF/BAF is a promising technology for advanced treatment of biologically pretreated coking wastewater.

Degradation analysis of A^2/O combined with AgNO3 + K2FeO4 on coking wastewater

In this work, a coking wastewater was selected and a biochemical Az/O treatment device for fractional degradation was designed and employed. After each stage of the treatment, the products were analyzed through gas chromatography-mass spectroscopy （GC-MS） to determine their composition. Finally, AgNO3 ＋ K2FeO4 was used as an advanced deep catalytic oxidation treatment. It was concluded from the analysis that cyclic organics could be degraded and the chemical oxygen demand （COD） was controlled within 50 mg. L-1, in line with the target value, Meanwhile, the spectra obtained from the GC-MS were in accordance with the conclusions reached based on the COD. The research results showed that all hard-degradable organics in coking wastewater could be eliminated through the A2/O bio-membrane treatment and the advanced treatment of making use of K2FeO4 as an oxidant and Ag＋ as a catalyst, the catalytic efficiency with Ag＋ as a catalyst of K2FeO4 was very high. Ag＋ could evidently improve the oxidation capacity of K2FeO4 to wastewater in its short stability time, and this is an important innovation.

Dynamics study on effect of temperature to Nitrous nitrification reaction of coking wastewater

Dynamic effects of NO2--N accumulation were discussed owing to temperature.In different temperature,a series of vmax and Ks were found considering the relation between the temperature and rate of ammonia nitrogen transforming into NO2--N.The kinetics models,which reflected the conditions of ammonia nitrogen transforming into NO2--N in the treatment process of the coking wastewater,were built up.The characteristic coefficient temperature was determined according to Arrhenius.

The influence of nitrified supernate’s recycle ratio on the removal of coking wastewater

The influence of the recycle ratio on the removal of coking wastewater has been researched using the anaerobicanoxic-aerobic （A/A/O） biofilm process. The research indicates that the concentrations of chemical oxygen demand （COD） and NO3 -N in the water are the lowest when the recycle ratio is 3：1 ,but the removal efficiency of total cyanide （TCN） is the highest when the recycle ratio is 1： 1. The removal efficiency of NH4^＋ -N is more than 99% at all three different recycle ratios. Compared with Grade A of the National Discharge Standard （GB 8978--1996）, the effluent NH4 -N is standard,but COD and TCN can not meet the requirements and further treatment processes are needed.

Treatment of the wastewater from the sintering flue gas desulfurization process

The limestone-gypsum flue gas desulfurization （FGD） process has become the most widespread process in the world for sulfur removal. The swirl-jet-absorbing wet limestone-gypsum sintering FGD technology was developed for sintering flue gas desulfurization,and this process produces volumes of wastewater with various contaminants that requires treatment before disposal or reuse. In this study, the wastewater quality from three different sintering FGD systems at Baosteel Group was investigated and compared with wastewater from power plant FGD. A treatment process was proposed which is suitable for sintering FGD wastewater. After treatment with a neutralization, coagulation and sedimentation process, heavy metals in the sintering FGD wastewater were reduced to a level meeting the relevant emission standards ,but the pH and ammonia concentration were too high, and a further treatment process was needed. Due to certain similarities and complementarities between sintering FGD wastewater and coking wastewater, it is entirely feasible to mix the pretreated sintering FGD wastewater into a biological coking wastewater treatment system. This study indicates that it is entirely feasible to mix pretreated sintering FGD wastewater into the biological treatment systems used for coking wastewater from the iron and steel industries.

Assessing quinoline removal performances of an aerobic continuous moving bed biofilm reactor(MBBR) bioaugmented with Pseudomonas citronellolis LV1

This study evaluated the bioaugmentation potential of a quinoline-degrading strain Pseudomonas citronellolis LV1 inoculation into activated sludge for treating quinoline wastewater, and results indicated the inoculation of LV1 in aerobic continuous MBBR could substantially improve the quinoline removal performance with an improved removal efficiency of 34% averagely when quinoline was used as the sole carbon and nitrogen source. Additionally, efficient removal of quinoline in enhanced MBBR occurred at the influent p H of 7.0–8.0, hydraulic retention time(HRT) of 24–28 h and influent quinoline concentration of 100–700 mg·L^(-1). High-throughput sequencing analysis indicated that bioaugmentation could increase microbial diversity and shape the microbial community structure. Although the inoculant LV1 did not remain its dominance in stage Ⅲ, bioaugmentation indeed induced the formation of effective microbial community, and the indigenous microbes including Flavobacterium, Pseudoxanthomonas,Pseudomonas, Vermamoeba, Dyadobacter and Sphingomonas might play the key role in quinoline removal.According to the PICRUSt, the enhanced genes encoding aromatic ring-cleavage enzyme, especially for Nheterocyclic ring-cleavage enzymes, could lead to the improved removal performance of quinoline in bioaugmentation stage. Moreover, the enhanced MBBR treated well actual coking wastewater, as indicated by high removal performance of quinoline, phenol and COD.

Temporal assembly patterns of microbial communities in three parallel bioreactors treating low-concentration coking wastewater with differing carbon source concentrations

Carbon source is an important factor of biological treatment systems, the effects of which on their temporal community assembly patterns are not sufficiently understood currently.In this study, the temporal dynamics and driving mechanisms of the communities in three parallel bioreactors for low-concentration coking wastewater(CWW) treatment with differing carbon source concentrations(S0 with no glucose addition, S1 with 200 mg/L glucose addition and S2 with 400 mg/L glucose addition) were comprehensively studied. Highthroughput sequencing and bioinformatics analyses including network analysis and Infer Community Assembly Mechanisms by Phylogenetic bin-based null model(iCAMP) were used. The communities of three systems showed turnover rates of 0.0029~0.0034 every 15days. Network analysis results showed that the S0 network showed higher positive correlation proportion(71.43%) and clustering coefficient(0.33), suggesting that carbon source shortage in S0 promoted interactions and cooperation of microbes. The neutral community model analysis showed that the immigration rate increased from 0.5247 in S0 to 0.6478in S2. The iCAMP analysis results showed that drift(45.89%) and homogeneous selection(31.68%) dominated in driving the assembly of all the investigated microbial communities.The contribution of homogeneous selection increased with the increase of carbon source concentrations, from 27.92% in S0 to 36.08% in S2. The OTUs participating in aerobic respiration and tricarboxylic acid(TCA) cycle were abundant among the bins mainly affected by deterministic processes, while those related to the metabolism of refractory organic pollutants in CWW such as alkanes, benzenes and phenols were abundant in the bins dominated by stochastic processes.

Performance of a polymerization-based electrochemically assisted persulfate process on a real coking wastewater treatment

Industrial wastewater should be treated with caution due to its potential environmental risks.In this study,a polymerization-based cathode/Fe^(3+)/peroxydisulfate(PDS)process was employed for the first time to treat a raw coking wastewater,which can achieve simulta-neous organics abatement and recovery by converting organic contaminants into separable solid organic-polymers.The results confirm that several dominant organic contaminants in coking wastewater such as phenol,cresols,quinoline and indole can be induced to poly-merize by self-coupling or cross-coupling.The total chemical oxygen demand(COD)abate-ment from coking wastewater is 46.8%and the separable organic-polymer formed from or-ganic contaminants accounts for 62.8%of the abated COD.Dissolved organic carbon(DOC)abatement of 41.9%is achieved with about 89%less PDS consumption than conventional degradation-based process.Operating conditions such as PDS concentration,Fe3+concen-tration and current density can affect the COD/DOC abatement and organic-polymer yield by regulating the generation of reactive radicals.ESI-MS result shows that some organic-polymers are substituted by inorganic ions such as Cl^(-),Br^(-),I^(-),NH_(4)^(+),SCN^(-)and CN^(-),suggest-ing that these inorganic ionsmay be involved in the polymerization.The specific consump-tion of this coking wastewater treatment is 27 kWh/kg COD and 95 kWh/kg DOC.The values are much lower than those of the degradation-based processes in treating the same coking wastewater,and also are lower than those of most processes previously reported for coking wastewater treatment.

The significance of resource recycling for coking wastewater treatment:based on environmental and economic life cycle assessment

The sustainability of the coking industry is supported by reasonable production profit and environmental quality requirements.The traditional measures substantially increased the related costs for enterprises to reach standards.This paper aims to develop a comprehensive cost combined environmental impact assessment method that is necessary for the analysis of wastewater treatment systems.Typical three coking wastewater treatment processes in China were evaluated.Results showed that eutrophication dominantly contributed to the overall environmental effect.Improving effluent quality could significantly reduce the total environmental impact.In terms of an economic perspective,the price of raw materials was the main factor that affected the operating cost of comprehensive treatment.Based on subsystem analysis,the pretreatment stage accounted for the majority of environmental and cost burdens,respectively reaching 64%-78%and 64%-86%.Optimizing the pretreatment process by enhancing the efficiency of high concentration raw material recovery and substituting toxic raw materials for extractant could reduce the environmental impact and economic cost by 43.8%and 57%,respectively,which was an effective way to improve the potential performance of coking wastewater treatment plants(WWTPs).

Coking wastewater treatment for industrial reuse purpose: Combining biological processes with ultrafiltration, nanofiltration and reverse osmosis

A full-scale plant using anaerobic, anoxic and oxic processes （A1/A2/O）, along with a pilot-scale membrane bioreactor （MBR）, nanofiltration （NF） and reverse osmosis （RO） integrated system developed by Shanghai Baosteel Chemical Co. Ltd., was investigated to treat coking wastewater for industrial reuse over a period of one year. The removals reached 82.5% （COD）, 89.6% （BOD）, 99.8% （ammonium nitrogen）, 99.9% （phenol）, 44.6% （total cyanide （T-CN））, 99.7% （thiocyanide （SCN-）） and 8.9% （fluoride）, during the A1/A2/O biological treatment stage, and all parameters were further reduced by over 96.0%, except for fluoride （86.4%）, in the final discharge effluent from the currently operating plant. The pilot-scale MBR process reduced the turbidity to less than 0.65 NTU, and most of the toxic organic compounds were degraded or intercepted by the A1/A2/O followed MBR processes. In addition, parameters including COD, T-CN, total nitrogen, fluoride, chloride ion, hardness and conductivity were significantly reduced by the NF-RO system to a level suitable for industrial reuse, with a total water production ratio of 70.7%. However, the concentrates from the NF and RO units were highly polluted and should be disposed of properly or further treated before being discharged.

Removal of polycyclic aromatic hydrocarbons and phenols from coking wastewater by simultaneously synthesized organobentonite in a one-step process

The optimal condition for a one-step process removing organic compounds from coking wastewater by simultaneously synthesized organobentonite as a pretreatment was investigated.Results showed that sorption of organic compounds by organobentonite was positively correlated to the cation surfactant exchange on the bentonite and the octanol-water partition coefficient（Kow） of the solutes.With 0.75 g/L bentonite and 180 mg/L（60% of bentonite cation exchange capacity） cetyltrimethylammonium bromide,the removal efficiencies of the 16 polycyclic aromatic hydrocarbon（PAHs） specified by the US Environmental Protection Agency in coking wastewater except naphthalene were more than 90%,and that of benzo（a）pyrene was 99.5%.At the same time,the removal efficiencies of CODCr,NH3-N,volatile phenols,colour and turbidity were 28.6%,13.2%,8.9%,55% and 84.3%,respectively,and the ratio of BOD5/CODCr increased from 0.31 to 0.41.These results indicated that the one-step process had high removal efficiency for toxic and refractory hydrophobic organic compounds,and could improve the biodegradability of the coking wastewater.Therefore it could be a promising technology for the pretreatment of toxic and refractory organic wastewater.

Coking wastewater increases micronucleus frequency in mouse in vivo via oxidative stress

Coking wastewater has caused serious health risk in coal-producing areas of China, however its toxic effects have not been well understood. The genotoxicity induced by coking wastewater on mice in vivo and its possible oxidative mechanisms were investigated via observing the induction of micronuclei in polychromatic erythrocytes of mouse bone marrow, and subsequently determining the antioxidative enzyme activities （superoxide dismutase Cu, Zn-SOD, Se-dependent glutathione peroxidase, and catalase）, thiobarbituric acid reactive substance contents and protein carbonyl levels in brains and livers of mice. Results showed that the tested coking wastewater caused a significant increase of micronucleus frequencies in a concentration-dependent manner. Also, the sample increased lipid peroxidation and protein oxidation levels, which was accompanied by changes in antioxidative status. Interestingly, pre-treatment with an antioxidant （vitamin C） led to a statistical reduction in the micronucleus frequency caused by coking wastewater. This implies that coking wastewater induces evident genetic damage in mammalian cells, and exposure to polluted areas might pose a potential genotoxic risk to human beings; in the process, oxidative stress played a crucial role.

Revealing the anaerobic acclimation of microbial community in a membrane bioreactor for coking wastewater treatment by Illumina Miseq sequencing

The dynamic change of microbial community during sludge acclimation from aerobic to anaerobic in a MBR for coking wastewater treatment was revealed by Illumina Miseq sequencing in this study. The diversity of both Bacteria and Archaea showed an increase–decrease trajectory during acclimation, and exhibited the highest at the domestication interim. Ignavibacteria changed from a tiny minority（less than 1%） to the dominant bacterial group（54.0%） along with acclimation. The relative abundance of Betaproteobacteria kept relatively steady, as in this class some species increased coupled with some other species decreased during acclimation. The dominant Archaea shifted from Halobacteria in initial aerobic sludge to Methanobacteria in the acclimated anaerobic sludge. The dominant bacterial and archaeal groups in different acclimation stages were indigenous microorganisms in the initial sludge, though some of them were very rare. This study supported that the species in＂rare biosphere＂ might eventually become dominant in response to environmental change.