Overview of enhancing biological treatment of coal chemical wastewater:New strategies and future directions

Coal chemical wastewater(CCW)is a type of refractory industrial wastewater,and its treatment has become the main bottleneck restricting the sustainable development of novel coal chemical industry.Biological treatment is considered as an economical,effective and environmentally friendly technology for CCW treatment.However,conventional biological process is difficult to achieve the efficient removal of refractory organics because of CCW with the characteristics of composition complexity and high toxicity.Therefore,seeking the novel enhancement strategy appears to be a favorable solution for enhancing biological treatment efficiency of CCW.This review focuses on presenting a comprehensive picture about the exogenous enhancement strategies for CCW biological treatment.The performance and potential application of exogenous enhancement strategies,including co-metabolic substrate enhancement,biofilm filler enhancement,adsorption material enhancement and conductive mediator enhancement,were expounded.Meanwhile,the enhancing mechanisms of different strategies were comprehensively discussed from a biological perspective.Furthermore,the prospects of enhancement strategies based on the engineering performance,economic cost and environmental impact(3E)evaluation were introduced.And novel enhancement strategy based on“low carbon emissions”,“resource recycling”and“water environment security”in the context of carbon neutrality was proposed.Taken together,this review provides technical reference and new direction to facilitate the regulation and optimization of typical industrial wastewater biological treatment.

Advances Treatment Technologies in Chemical Industry Wastewater

The main treatment methods of chemical wastewater were reviewed.Physical,chemical,and biochemical treatment technologies effective for removing those pollutants were presented with their applicability,effectiveness and advantages.The problems facing the wastewater treatment in the petroleum chemical industry and coal chemical industry were introduced.In the end,the new progress and trend of the processes were overviewed.

Treatment of Slightly Polluted Wastewater in an Oil Refinery Using a Biological Aerated Filter Process

The slightly polluted wastewater from oil refinery contains some COD, oil pollutants and suspended solids （SS）. A small-scale fixed film biological aerated filter （BAF） process was used to treat the wastewater. The influences of hydraulic retention time （HRT）, air/water volume flow ratio and backwashing cycle on treatment efficiencies were investigated. The wastewater was treated by the BAF process under optimal conditions： the HRT of 1.0 h, the air/water volume flow ratio of about 5 ： 1 and the backwashing cycle of every 4-7 days. The results showed that the average removal efficiency of COD, oil pollutants and SS was 84.5%, 94.0% and 83.4%, respectively. And the average effluent concentration of COD, oil pollutants and SS was 12.5, 0.27, 14.5 mg·L^-1, respectively. The experimental results demonstrated that the BAF process is a suitable and highly efficient method to treat the wastewater.

United membrane biological reactor in the treatment of wastewater

The united membrane biological reactor(UMBR) was studied for the treatment of some simulate and municipal wastewater. The removal efficiency for COD and turbidity are greater than 80% and 99% respectively. Effluent COD is less than 100 mg/L while turbidity less than 5 The removal of LAS in bath wastewater is greater than 70%. In treatment of dinning hall wastewater, removal of fatty oil is greater than 90%, and its concentration in effluent is less than 5 mg/L. The match of biological reactor and the membrane separation component were calculated. The stable performance of wastewater treatment can be maintained by the optimization of operation conditions and the cleanout of membranes.

Simulation of Low TDS and Biological Units of Fajr Industrial Wastewater Treatment Plant Using Artificial Neural Network and Principal Component Analysis Hybrid Method

Being familiar with characteristics of industrial town effluents from various wastewater treatment units, which have high qualitative and quantitative variations and more uncertainties compared to urban wastewaters, plays very effective role in governing them. With regard to environmental issues, proper operation of wastewater treatment plants is of par- ticular importance that in the case of inappropriate utilization, they will cause serious problems. Processes that exist in environmental systems mostly have two major characteristics: they are dependent on many variables;and there are complex relationships between its components which make them very difficult to analyze. In order to achieve a better and efficient control over the operation of an industrial wastewater treatment plant (WWTP), powerful mathematical tool can be used that is based on recorded data from some basic parameters of wastewater during a period of treatment plant operation. In this study, the treatment plant was divided into two main subsystems including: Low TDS (Total Dissolved Solids) treatment unit and Biological unit (extended aeration). The multilayer perceptron feed forward neural network with a hidden layer and stop training method was used to predict quality parameters of the industrial effluent. Data of this study are related to the Fajr Industrial Wastewater Treatment Plant, located in Mahshahr—Iran that qualita- tive and quantitative characteristics of its units were used for training, calibration and validation of the neural model. Also, Principal Component Analysis (PCA) technique was applied to improve performance of generated models of neural networks. The results of L-TDS unit showed good accuracy of the models in estimating qualitative profile of wastewater but results of biological unit did not have sufficient accuracy to being used. This model facilitates evaluating the performance of each treatment plant units through comparing the results of prediction model with the standard amount of outputs.

Advanced Treatment of Biologically Treated Chemical Comprehensive Wastewater by Nano-TiO2 Photocatalytic Oxidation

Nano-TiO2 photocatalytic oxidation was used to perform the advanced treatment of biologically treated chemical comprehensive wastewater. The effects of reaction time,nano-TiO2 dosage and initial p H of the wastewater on the removal rate of COD were tested. The GC/MS and EEM techniques were used to qualitatively analyze organic compounds in the wastewater before and after treatment. The result showed that after the biologically treated chemical comprehensive wastewater was treated by nano-TiO2 photocatalytic oxidation under the conditions of reaction time 3 h,nano-TiO2 dosage 8 g/L,and pH 8. 0,the effluent COD was 61. 9 mg/L and its removal rate was 63. 8%. Additionally,the species of organic pollutants reduced from 12 to 6. Meanwhile,the content of humic-like and fulvic-like substances dropped dramatically.

Effect of Domestic Wastewater as Co-Substrate on Biological Stain Wastewater Treatment Using Fungal/Bacterial Consortia in Pilot Plant and Greenhouse Reuse

In this study, a pilot wastewater treatment plant was used to evaluate the co-treatment of biological-staining residues and domestic wastewater under non-sterile conditions. A novel microbial consortia formed by Trametes versicolor, Trametes sp, Pleurotus ostreatus, Pseudomonas fluorescens, Pseudomonas azotoformans, Pseudomonas sp, Enterobacter xianfangensis and Bacillus subtillis was inoculated in an extended aeration type bio-reactor. The treatment units were operated during three consecutive cycles during a period of 147 h. After the last operating cycle, the concentrations of Chemical Oxygen Demand, Biochemical Oxygen Demand, Color Units, Total suspended solids, and the pH value were 1695 mg/L, 105 mg/L, 106 CU, 5), 1367 (CU), 566 mg/L (TSS) and 7.0 (pH) respectively. The reduction of pollutants load was related with the ratio of the two types of wastewater (3.5:0.5) combined to increase biodegradability, the concentration of fungi and bacteria used in the consortia (30 × 103 - 55 × 106 CUF/mL Total Fungi and 70 × 107 - 83 × 108 CFU/mL of Total Bacteria) and ligninolytic enzymes production, Laccase (13 - 96 U/L), MnP (9.8 - 39 U/L) and LiP (0.3 - 5.3 U/L). The post-treated effluent was used as irrigation water. Lolium perenne plants were watered during 60 days with post-treated effluent. The results of root weight showed that there are significant differences between the initial water and the effluent obtained after the operational cycles (p = 0.00470). The highest root weights (1 - 1.12 g) were found in plants irrigated with water obtained from the last treatment cycle.

Evaluation of the Inverse Fluidized Bed Biological Reactor for Treating High-Strength Industrial Wastewaters

The aim of this work was to investigate the aerobic degradation of high-strength industrial (refinery) wastewaters in the inverse fluidized bed biological reactor, in which polypropylene particles of density 910 kg/m3 were fluidized by an upward flow of gas through a bed. Measurements of chemical oxygen demand (COD) versus residence time t were performed for various ratios of settled bed volume to reactor volume (Vb/VR) and air velocities u. The largest COD reduction, namely, from 54,840 to 2,190 mg/l, i.e. a 96% COD decrease, was achieved when the reactor was operated at the ratio (Vb/VR) = 0.55, air velocity u = 0.046 m/s and t = 65 h. Thus, these values of (Vb/VR), u and t can be considered as the optimal operating parameters for a reactor when used in treatment of high-strength refinery wastewaters. In the treatment operation conducted in a reactor optimally controlled at (Vb/VR) = 0.55, u = 0.046 m/s and t = 65 h, the conversions obtained for all phenolic constituents of the wastewater were larger than 95%. The conversions of about 90% were attained for other hydrocarbons.

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.

Fluidized-Bed Bioreactor Applications for Biological Wastewater Treatment： A Review of Research and Developments

污水处理是保护环境和人类健康的重要过程。目前,最经济有效的污水处理方法为生物处理法,如运行时间较长的活性污泥法。然而,随着人口的增长,对新型高效污水处理技术的需求越来越迫切,流态化技术虽然已展示出能够提高许多化学与生化处理过程的效率,但尚未在大型污水处理过程中得到广泛的应用。循环流化床生物反应器(CFBBR)污水处理技术的研究始于加拿大西安大略大学,在该技术中,载体颗粒表面会形成一层含细菌与其他微生物的生物膜,并在反应器中呈流化状态;流态化固有的良好混合和质量传递特性,使得该技术在生活污水和工业污水处理过程中均具优势。实验室阶段和中试阶段的研究均证实了CFBBR可去除污水中90%以上的碳源、80%以上的氮源,且污泥产量少于活性污泥法的1/3。由于该技术的高效性,CFBBR还可被用于传统方法难以处理的高有机碳污水处理,且具有占地面积小的优势。同时,CFBBR在动态负荷试验(进水量和进水浓度变化)中也展现了良好的抗冲击和恢复性能。总的来说,CFBBR是一种高效的污水处理方法,可在较短的水力停留时间和较小的反应器体积内处理更多的污水。此外,该反应器的紧凑设计将有助于在偏僻地区建造独立的污水处理系统。

Enhancing Biological Wastewater Treatment with Chitosan

Chitin and chitosan have been applied to biological wastewater treatment.From a number of parallel comparison experiments,it can be concluded that the application of chitin and chitosan can both enhance the biological treatment,besides which chitosan is more efficient than chitin.The study on the enhancement mechanism reveals the difference between the two additives:chitosan improves the sludge structure and settlibility,while chitin acts as a kind of carrier for microorganism in the biological treatment system.

Effects of Micronutrient Niacin on Treatment Efficiency of Textile Wastewater

Textile wastewater is well known as one of the wastewaters to be most difficultly treated. The effects of niacin on textile wastewater treatment efficiency were studied by continuous addition of 1.0 mg·L^-1 niacin, the physical and chemical indexes of the water samples, such as COD, ammonia and dehydrogenase activities, were analyzed every day with standard methods, and obvious improvement in wastewater treatment performance was achieved. The exact results showed that：① Niacin could improve the COD removal efficiency signifcantly with removal rates being 1.31 times as to those of the control system; ② under this experimental condition, addition of niacin had almost no effect on the removal of ammonia;③ Addition of niacin could improve the activity of dehydrogenase by 130 %. It proved that the biological treatment performance of textile wastewater treatment system probably could be optimized through micronutrient niacin supplement.

Purification and reclamation of wastewater by an integrated biological pond system

The feasibility of an inexpensive wastewater treatment system is evaluated in this study.The experiment was conducted in 3 phases with different treatment combinations for testing theirpurification efficiencies. The pond system was divided into 3 functional regions: influentpurification, efficient upgrading and multi-utilization. Various kinds of aquatic organisms, wereeffectively cooperated in this system. The system attained high reduction of BOD_5, COD, TSS, TN,TP and other pollutants. The mutagenic effect and number of bacteria and virus significantly de-clined during the process of purifieation. After the wastewater flowed through the upgrading zone,the concentrations of pollutants and algae evidently decreased. Plant harvesting did not yield drama-tic effects on reductions of the main pollutants, through it did affect remarkably the biomassproductivity of the macrophytes. The wastewater was reclaimed for various purposes.

Some Characteristics of Treatment of Wastewater from Paper Production and Recycling Containing Lignin in Vietnam

Lignin is a difficult-to-treat pollutant in wastewater from paper production and paper recycling.But lignin and lignin derivatives are useful materials in many different fields.This paper summarizes some characteristics of the lignin recovery process,lignin application and lignin treatment.And the paper also presents some characteristics in paper wastewater treatment,paper recycling wastewater in Vietnam.

Optimal Aerations in the Inverse Fluidized Bed Biofilm Reactor When Used in Treatment of Industrial Wastewaters of Various Strength

The aim of this work was the determination of the optimal aerations, and more specifically the corresponding optimal air velocities uopt, at which the largest COD removals were achieved in treatment of industrial wastewaters of various strength conducted in the inverse fluidized bed biofilm reactor. The largest COD removals were achieved at the following air velocities uopt and retention times ts, and (Vb/VR) = 0.55: i) for CODo = 72,780 mg/l at uopt = 0.052 m/s and ts = 80 h;ii) for CODo = 62,070 mg/l at uopt = 0.042 m/s and ts = 65 h;iii) for CODo = 49,130 mg/l at uopt = 0.033 m/s and ts= 55 h;iv) for CODo = 41,170 mg/l at uopt = 0.028 m/s and ts = 45 h;v) for CODo = 35,460 mg/l at uopt = 0.025 m/s and ts = 27.5 h;and vi) for CODo = 26,470 mg/l at uopt= 0.014 m/s and ts = 22.5 h. In the treatment operation conducted in a reactor optimally controlled at the above values of uopt, ts and (Vb/VR), the following decreases in COD were obtained: i) from 72,780 to 5410 mg/l;ii) from 62,070 to 3730 mg/l;iii) from 49,130 to 2820 mg/l;iv) from 41,170 to 1820 mg/l;v) from 35,460 to 1600 mg/l;and vi) from 26,470 to 1180 mg/l, that is, approximately a 93%, 94%, 95%, 96%, 95% and 96% COD reduction was attained, respectively.

Enhanced biological nutrients removal using an integrated oxidation ditch with vertical circle from wastewater by adding an anaerobic column

Compared to conventional oxidation ditches, an integrated oxidation ditch with vertical circle （IODVC） has the characters of concise configuration, simple operation and maintenance, land saving and automatical sludge returning. By the utilization of vertical circulation, an aerobic zone and an anoxic zone can be unaffectedly formed in the IODVC. Therefore, COD and nitrogen can be efficiently removed. However, the removal efficiency of phosphorus was low in the IODVC. In the experiment described, a laboratory scale system to add an anaerobic column to the IODVC has been tested to investigate the removal of phosphorus from wastewater. The experimental results showed that the removal efficiency of TP with the anaerobic column was increased to 54.0% from 22.3% without the anaerobic column. After the acetic sodium was added into the influent as carbon sources, the mean TP removal efficency of 77. 5 % was obtained. At the same time, the mean removal efficiencies of COD, TN and NH3-N were 92.2%, 81.6% and 98.1%, respectively, at 12 h of HRT and 21-25 d of SRT. The optimal operational conditions in this study were as follows： recycle rate = 1.5-2.0, COD/TN 〉 6, COD/TP 〉 40, COD loading rate = 0.26-0.32 kgCOD/（kgSS· d）, TN loading rate = 0. 028-0. 034 kgTN/（ kgSS·d） and TP loading rate = 0.003-0.005 kgTP/（kgSS· d）, respectively.

Developments in Biological Treatment of Industrial Wastewaters

The characteristics and biological treatment technologies of several kinds of industrial wastewater are summarised. Biological treatment of industrial wastewater is a well established system with applications going back for over a century. However, developments are still taking place but at the design stage, more emphasis will be placed on small “footprint” systems, odour control and minimization of excess sludge production.

New concept of contaminant removal from swine wastewater by a biological treatment process

Pollution from concentrated animal feeding operations(CAFOs)are the most serious pollution source in China now,and swine wastewater contains high concentrations of nutrients such as chemical oxygen demand(COD),biochemical oxygen demand 5(BOD 5),ammonium,and emergent contaminants related to public health.Biological processes are the most popular treatment methods for COD and ammonium removal.Considering the low operation cost,easy maintenance and high removal rate of contaminants in recent years,nitrogen removal via nitrite and real-time control processes using oxidation-reduction potential(ORP)and/or pH as parameters to control the aerobic and anaerobic cycles of a system has received much attention for animal wastewater treatment.During the biological treatment process,the emergent contaminants such as estrogen,antibiotics,and disinfec-tion reagents have been the focus of research recently,and degradation bacteria and resistance bacteria have also been extracted from activated sludge.The microbial analysis technique is also advancement in the field of biodegrada-tion bacteria and resistance bacteria.All of these advance-ments in research serve to improve wastewater treatment and decrease environmental hazards,especially for using manure as a fertilizer source for crop production.

Process Optimization of Effective Partition Constant in Progressive Freeze Concentration of Wastewater

Response surface methodology (RSM) was employed to optimize the process parameters for effective partition constant (K) in progressive freeze concentration (PFC) of wastewater. The effects of coolant temperature, circulation flowrate, initial solution concentration and circulation time on the effective partition constant were observed. Results show that the data were adequately fitted into a second-order polynomial model. The linear and quadratic of independent variables, coolant temperature, circulation flowrate, initial solution concentration and circulation time as well as their interactions have significant effects on the effective partition constant. It was predicted that the optimum process parameters within the experimental ranges for the best K would be with coolant temperature of -8.8℃, circulation flowrate of 1051.1 ml/min, initial solution concentration of 6.59 mg/ml and circulation time of 13.9 minutes. Under these conditions, the effective partition constant is predicted to be 0.17.