Purified Terephthalic Acid Wastewater Research Articles

Dual-chamber up-flow fluidized hollow-fiber anaerobic membrane bioreactor (UF-HF-AnMBR) treating synthetic purified terephthalic acid wastewater: Granular sludge regranulation and methane production

Up-flow anaerobic sludge blanket is a representative way to treat high-strength industrial wastewater, but suffers from granule collapse and poor long-term performance. In this study, a dual-chamber up-flow fluidized hollow-fiber anaerobic membrane bioreactor (UF-HF-AnMBR) was constructed to enhance sludge regranulation and process stability for purified terephthalic acid (PTA) wastewater treatment. A stable and satisfactory aromatic compound removal (>99 %) was achieved at the organic loading rate of 7.15 ± 0.21 g-COD·Lreactor−1·d−1, with the methane yield of 0.345 ± 0.028 L·g-CODremoved−1. Although the granular sludge collapsed initially induced the pore blocking and membrane fouling, membrane separation promoted the agglomeration of small particles, sludge regranulation and biomass retention. Parallel factor analysis identified that the amino acid tryptophan in extracellular polymeric substances exerted a more critical effect on membrane fouling. The 16S rRNA and network analysis revealed the robust proliferation/enrichment of Methanosaeta, Pelotomaculum, etc., as well as the establishment of mutualistic symbiotic relationship among different species, ensured a stable microbial community and created a favorable circumstance for highly effective anaerobic treatment of PTA wastewater. This study proves that UF-HF-AnMBR can be an efficient and promising technique for sludge regranulation and microbe enrichment, advancing its application in PTA wastewater treatment and bioenergy recovery.

Comprehensive study of the kinetics of combustion and pyrolysis of petrochemical sludge: Experimentation and application of artificial neural network

Energy can be obtained from the pyrolysis and combustion of purified terephthalic acid (PTA) sludge which is produced during the treatment of PTA wastewater. In this study, the combustion and pyrolysis behaviors and kinetics of the sludge produced from the thermochemical treatment of PTA wastewater were analyzed under non-isothermal heating. It was found that reaction orders were in the range of 1–3 for oxidation/combustion. The reactions were exothermic, as indicated by the negative change in enthalpy. The phenomenon of auto gasification was observed during pyrolysis for three sludges. The analysis of the change of activation energy with the degree of conversion showed that several parallel reactions occurred at the beginning of the sludge decomposition during air combustion. The value of activation energy for CuSO4, FeCl3 and FeCl3 + CPAA sludge was 99.5 kJ/mol, 109 kJ/mol and 118.7 kJ/mol, respectively, for pyrolysis and 116.3 kJ/mol, 68.8 kJ/mol, and 127.9 kJ/mol, respectively, for combustion. These sludges are promising for energy recovery because they have a high net calorific value (NCV) and a high gross calorific value (GCV). The GCV was 22.4 MJ/kg, 19.8 MJ/kg, and 28.4 MJ/kg for CuSO4, FeCl3, and FeCl3 with CPAA, respectively and the NCV was 22.3 MJ/kg, 18.6 MJ/kg, and 27.3 MJ/kg for CuSO4, FeCl3, and FeCl3 with CPAA, respectively. The artificial neural network was used to validate the experimental results. The correlation coefficient between the expected and experimental results were 0.9945, 0.9980 and 0.9980 for CuSO4, FeCl3 and FeCl3 +CPAA sludge for pyrolysis, respectively and 0.9989, 0.9963 and 0.9968 for CuSO4, FeCl3 and FeCl3 +CPAA sludge for combustion, respectively. The developed ANN model successfully predicts the combustion and pyrolytic process for petrochemical sludge under specified conditions.

Waste carbon conversion and utilization in chemical wastewater treatment process: Experimental approaches from lab-to pilot-scale

Chemical wastewater often contains large amounts of waste organic carbon. The current chemical wastewater treatment plants are an open carbon emission system. Inspired by the topic of CO2 conversion and utilization, this study provided a redesigned flowchart of chemical wastewater treatment process via closed-loop carbon conversion and utilization system for the resource utilization of waste carbon from wastewater. Purified terephthalic acid (PTA) wastewater, a common chemical wastewater, was selected to test the feasibility of the proposed strategy. An integrated closed-loop system involving activated sludge-microalgae-pyrolysis process was employed. Initially, a laboratory-scale wastewater treatment system combining activated sludge with microalgae process was applied for the carbon conversion and utilization in PTA wastewater. The COD removal efficiency was obtained at 93.02%, and over 94% of CO2 was captured. Microbial DNA analysis of the activated sludge indicated that the functional microorganisms mainly included Proteobacteria, Bacteroidetes, and Chloroflexi. Metabolic analysis of the microalgae showed that the abundances of differential metabolites associated with carbon metabolism significantly increased after treatment. Furthermore, a pilot-scale integrated system was applied to test this strategy and in which obtained a good performance in COD removal and CO2 capture. The produced excess biomass during chemical wastewater treatment, which was usually viewed as hazardous solid waste, was converted to biochar and carbonaceous combustible gas via pyrolysis. The produced biochar could be used as photocatalysts to remove antibiotic. The findings provided a new design to simultaneously achieve water pollution control, carbon conversion & utilization, and resource & energy recovery in chemical wastewater treatment process.

Long-term performance, membrane fouling behaviors and microbial community in a hollow fiber anaerobic membrane bioreactor (HF-AnMBR) treating synthetic terephthalic acid-containing wastewater

Purified terephthalic acid (PTA) wastewater with properties of poor biodegradation and high toxicity is produced from refining and synthesis of petrochemical products. In this study, a lab-scale hollow fiber membrane bioreactor (HF-AnMBR) fed with synthetic PTA wastewater was operated over 200 days with stepwise decreased hydraulic retention time (HRT) to investigate the long-term performance, membrane fouling mechanism and microbial community evolution. Results showed that a stable chemical oxygen demand (COD) removal rate of 65.8 ± 4.1% was achieved at organic loading rate of 3.1 ± 0.3 g-COD/L-reactor/d and HRT 24 h, under which the methane production rate reached 0.33 ± 0.02 L/L-reactor/d. Further shortening HRT, however, led to the decreased COD removal efficiency and low methane bioconversion. A mild membrane fouling occurred due to the production of colloidal biopolymers and the interaction between increased colloidal substances secreted/cracked by microorganisms and membrane interface. Further 16S rRNA analysis indicated that microbial diversity and richness had changed with the variation of HRT while Methanosaeta, and Methanolinea species were always the dominant methanogens responsible for methane production. The results verify that HF-AnMBR is an alternative technology for PTA wastewater treatment along with energy harvesting, and provide a new avenue toward sustainable petrochemical wastewater management.

Treatment of Purified Terephthalic Acid Wastewater by Ozone Catalytic Oxidation Method

In this study, a Cu–Ce@Az ozone catalyst with multiple active components was prepared through the impregnation method to treat purified terephthalic acid (PTA) wastewater, and characterized by X-ray diffraction, X-ray fluorescence spectroscopy, scanning electron microscopy, specific surface area analysis, X-ray energy spectroscopy, X-ray photoelectron spectroscopy, and other methods. The Cu–Ce@Az ozone catalyst had a developed pore structure with a large specific surface area and crystal structure. After calcination, the metallic elements Cu and Ce existed in the state of oxides CuO and CeO2. The effects of reaction time, solution pH, catalyst dosage, and ozone dosage on the catalytic oxidation performance of the Cu–Ce@Az ozone catalyst were studied. Adding tert-butanol reduced the removal rate of COD from the PTA wastewater through the catalytic oxidation system, which proves that a Cu–Ce@Az ozone catalyst treatment process of PTA wastewater follows the free-radical reaction mechanism. The results of 3D fluorescence spectroscopy analysis show that the organic matter in the PTA wastewater was converted into tryptophan organic matter and aromatic organic matter after the reaction of the catalytic oxidation system. Ultraviolet absorption spectroscopy analysis indicated that in unsaturated chemical bonds, some conjugated structures and benzene ring structures of organic matter in the PTA wastewater were destroyed.

Utilization of chemical wastewater for CO2 emission reduction: Purified terephthalic acid (PTA) wastewater-mediated culture of microalgae for CO2 bio-capture

The present study aimed to prove the potential of chemical wastewater utilization for CO2 emission reduction. Purified terephthalic acid (PTA) wastewater was applied as the culture medium of green microalgae (Chlorella pyrenoidosa) for CO2 bio-capture. Algal biomass and chlorophyll a content were determined as algal physiological response, and the CO2 capture efficiency and photosynthetic rate were also evaluated. Due to low pH value (pH = 4.40), the alga was unable to grow in the raw PTA wastewater, while it preferred tolerance and adaptation in the pH adjusted wastewater (pH = 7.40) and the treated PTA wastewater, respectively. Generally, 75.55–90.25 g/d of the algal biomass (dry weight) was yielded of the PTA wastewater per ton. While both chlorophyll a content of unit algal density and CO2 capture rate with the treated wastewater were higher than those with the untreated PTA wastewater. Additionally, the algal ability to fix CO2 was evaluated when the concentration of CO2 was set at 2%, 5%, 10% and 15%, respectively. Our results showed that the CO2 capture rate and the photosynthetic rate of the algae when cultured with the treated wastewater were higher than these with the untreated PTA wastewater. The highest algal CO2 capture rate was obtained as 82.15% (2% CO2, with untreated wastewater) and 91.59% (10% CO2, with treated wastewater), respectively. It is the first time to report algal CO2-capture with chemical wastewater-mediated culture, and our study provided a trinity model to achieve water saving, CO2 emission reduction and energy regeneration in an integrated strategy.

Selective adsorption of Co(II)/Mn(II) by zeolites from purified terephthalic acid wastewater containing dissolved aromatic organic compounds and metal ions

Selective separation and recovery of Co(II)/Mn(II) from purified terephthalic acid (PTA) production wastewater is very important to reduce the Co(II)/Mn(II) catalysts consumption and control the pollutant discharge. This work employed zeolites NaA, NaX, and HZSM-5 with different pore sizes and Na(I) contents to selectively separate and recover Co(II)/Mn(II) from PTA wastewater and to understand the adsorption mechanism. It is found that only NaA can exclusively adsorb Co(II)/Mn(II) through ion-exchange without adsorbing any aromatic organic compound (AOC); oppositely, HZSM-5 shows the highest adsorption capacity for AOCs but almost no adsorption for Co(II)/Mn(II); and NaX exhibits moderate adsorption capacities for both Co(II)/Mn(II) and AOCs. Moreover, pH can significantly impact the adsorption of both Co(II)/Mn(II) and AOCs due to the competitive adsorption between H(I) and Co(II)/Mn(II) and the electrostatic repulsion between AOCs and zeolites. The adsorption kinetics, isotherms, and thermodynamics were also investigated to lay a good basis for process development. Importantly, bench-scale experiments for simulating the industrial operation were carried out, and the results show that the adsorption capacity of the NaA particles for Co(II)/Mn(II) from the industrial PTA wastewater is 9.1/8.6 mg/g, respectively, without adsorbing any AOC. Therefore, an efficient strategy to selectively separate and recover Co(II)/Mn(II) from PTA wastewater was successfully developed.

Co-occurrence network analysis reveals thermodynamics-driven microbial interactions in methanogenic bioreactors.

Methanogenic bioreactors have been applied to treat purified terephthalic acid (PTA) wastewater containing complex aromatic compounds, such as terephthalic acid, para-toluic acid and benzoic acid. This study characterized the interaction of microbial populations in 42 samples obtained from 10 PTA-degrading methanogenic bioreactors. Approximately, 54 dominant populations (11 methanogens, 8 syntrophs and 35 functionally unknown clades) that represented 73.9% of total 16S rRNA gene iTag sequence reads were identified. Co-occurrence analysis based on the abundance of dominant OTUs showed two non-overlapping networks centred around aromatic compound- (group AR: Syntrophorhabdaceae, Syntrophus and Pelotomaculum) and fatty acid- (group FA: Smithella and Syntrophobacter) degrading syntrophs. Group AR syntrophs have no direct correlation with hydrogenotrophic methanogens, while those from group FA do. As degradation of aromatic compounds has a wider thermodynamic window than fatty acids, Group AR syntrophs may be less influenced by fluctuations in hydrogenotrophic methanogen abundance or may non-specifically interact with diverse methanogens. In both groups, network analysis reveals full-scale- and lab-scale-specific uncultivated taxa that may mediate interactions between syntrophs and methanogens, suggesting that those uncultivated taxa may support the degradation of aromatic compounds through uncharted ecophysiological traits. These observations suggest that organisms from multiple niches orchestrate their metabolic capacity in multiple interaction networks to effectively degrade PTA wastewater.

Treatment of toxic pollutants of purified terephthalic acid waste water: A review

Abstract This study provides the overview of various biological and physiochemical technologies used for treatment of purified terephthalic acid (PTA) wastewater. Electrocoagulation (EC) technology is effective and mostly used technology in the area of wastewater treatment therefore this study also provide some fundamental of electrocoagulation (EC) process i.e. scope, process steps, reaction mechanisms, design parameters, operating parameters etc. It was found that Terephthalic acid (TA), benzoic acid (BA) and p-toulic acid (p-TA) are the major pollutants of PTA wastewater and contributed higher chemical oxygen demand (COD). Therefore, various studies reported degradation of these pollutants using synthetic and industrial wastewater. This study provides the review of these pollutants whether they were treated in single and multicomponent mixture. This study also illustrates these pollutants based on their solubility, importance, harmful effects, market scenario and exposure limits etc. Study shows that advanced oxidation processes are the best for treatment of major pollutants of PTA wastewater.

Treatment of PTA Wastewater by Modified Anode Microbial Fuel Cell

The purpose of this study was to investigate the effect of different modified anodes on the microbial fuel cell(MFC) and the effect of MFC on the treatment of refractory wastewater. Based on a single room air cathode, the anode of MFC was modified by 0.10 g of tourmaline, 75% manganese bioxide/halloysite nanotube(MnO2/HNT) and multi-walled carbon nanotube-carboxyl(MWCNT-COOH), respectively. The results showed that, the removal rate of purified terephthalic acid(PTA) was higher than 70%, and the chemical oxygen demand(COD) removal rate was more than 79% in MFC with different modified anodes. Compared with others, MFC with MWCNT-COOH modified anode obtained the maximum output voltage and maximum power density, which were 529 mV and 252.73 mW·m-2, respectively.

Impacts of biostimulation and bioaugmentation on the performance and microbial ecology in methanogenic reactors treating purified terephthalic acid wastewater

Up-flow anaerobic sludge blanket (UASB) processes treating purified terephthalic acid (PTA) wastewater often face challenges associated with biomass loss. As excessive biomass loss could lead to deterioration of PTA removal, biostimulation and bioaugmentation were often practiced without understanding the microbial impact in UASB. Three laboratory-scale UASB reactors were operated with synthetic PTA wastewater as the feed, with two added with co-substrate (glucose or molasses) on Day 170 for 90 days, and one with external granules on Day 118. Throughout the operation, treatment performance was measured together with the analysis of microbial communities of biomass samples using 16S rRNA-based gene Illumina sequencing. Glucose amendment destabilized both terephthalic acid and para-toluic acid removal, while molasses amendment improved para-toluic acid removal. Both substrate addition generally led to decreases in the abundances of syntrophs and methanogens and increases in carbohydrate-fermenting bacteria in the granular sludge. Regarding bioaugmentation, paper mill granule addition led to a temporary crash of terephthalic acid removal for 42 days, and deterioration of para-toluic acid removal throughout the operation. Syntrophs and methanogens were observed to colonize on the paper mill granules after three months, meanwhile growth of methanogens were stimulated on the PTA granules added initially. Overall, proper level of molasses amendment and external granule inoculation could be promising strategies to make up for biomass loss during the operation of PTA-degrading UASB.

A comparative study of electrochemical degradation of benzoic acid and terephthalic acid from aqueous solution of purified terephthalic acid (PTA) wastewater

In this article, studies have been performed on the treatment of benzoic acid (BA), terephthalic acid (TPA) and COD from synthetic binary solution of PTA wastewater. Acid precipitation pretreatment of aqueous solution was performed initially at different pH (2–5) and temperature (15–60 °C). The acid treated solution was re-treated by electrochemical oxidation (EO) and electro-Fenton (EF) techniques using graphite electrodes. Independent operating parameters namely initial pH: (1–9), current density (A/m2): (30.48–91.45), electrolyte concentration (g/L): (0.5–1.5) and electrolysis time (min): (10–90) for EO process and pH (1–5), current density (A/m2): (30.48–91.45), Fe2+ concentration (mmol/L): (0.5–1.5) and electrolysis time (min): (10–90) for EF process were modeled and optimized by central composite design (CCD) in response surface methodology (RSM). The maximum removal efficiencies of the process during EF treatment were 80.45% of BA, 76.83% of TPA and 73.70% of COD with energy consumption (kWh/kg COD removed) – 19.39 at optimum operating conditions. During EC treatment removal capacities were 70.76%, 68.52% and 67.27% with 31.01 (kWh/kg COD removed) respectively. It was observed that EF process was more efficient than EO based on removals of BA, TPA and COD with minimum energy consumption.

Selective Adsorption of p-Xylene from Pure Terephthalic Acid Wastewater on Modified and Formed Zeolites

Different zeolites were screened to achieve the aim of effective selective removal of p-xylene (PX) from the pure terephthalic acid (PTA) wastewater, and the ZSM-5 zeolite modified by NH4Cl was chosen as a suitable adsorbent because of the maximum equilibrium adsorption capacity and the largest selectivity factor. The selectivity factors of PX to Co2+ and PX to Mn2+ can attain 1778.069 and 1875.650, respectively, and the saturation adsorption capacity of PX even increases to 126.10 mg·g–1. First, the adsorption experiments were conducted at 298.15, 308.15, 318.15, and 328.15 K with the initial concentration of PX ranging from 50 to 180 mg·L–1 in a batch adsorber. The Langmuir model agreed better with the experimental results than did the Freundlich model. The adsorption parameters of thermodynamics are ΔS = −17.83 J·mol–1·K–1, ΔH = −12.33 kJ mol–1, and ΔG < 0, respectively. It is demonstrated that the adsorption of PX on the H-ZSM-5 zeolite is a spontaneous and exothermic physisorption. Second, the kineti...

Treatment of purified terephthalic acid wastewater using a bio-waste-adsorbent bagasse fly ash (BFA).

Purified terephthalic acid (PTA) plant of a petrochemical unit generates wastewater having high pollution load. Acid treatment of this wastewater reduces the chemical oxygen demand (COD) load by more than 50%, still leaving substantial COD load (>1500mg/L) which should be removed. The present study reports on the use of a bio-waste-adsorbent bagasse fly ash (BFA) for the reduction of COD and other recalcitrant acids from this wastewater. The BFA showed basic character and was mesoporous with a BET specific surface area of 82.4m2/g. Optimum conditions for the adsorptive treatment of acid-pretreated PTA wastewater were found to be as follows: initial pH (pHi)=4, BFA dosage=15g/L, and contact time=3h. Adsorption treatment resulted in 58.2% removal of COD, 96.3% removal of terephthalic acid (TA), and 99.9% removal of benzoic acid (BA). TA and BA were removed from the pretreated PTA wastewater through precipitation and sedimentation of un-dissociated acid molecules inside the mesopores of the BFA. The results showed that the COD removed by the BFA followed pseudo-second-order kinetics. Equilibrium sorption data were best correlated by the Freundlich isotherm. The process of adsorptive removal of COD was found to be exothermic. The change in the Gibbs free energy was found to be negative, suggesting that the adsorption process is spontaneous and feasible for the treatment of PTA wastewater.

Removal of COD in Purified Terephthalic Acid (PTA) Effluent with Coagulation, Aqueous Oxidation and High Porosity Membrane

Present study was focused on purified terephthalic acid (PTA) industry wastewater treatment located at Port Qasim, Karachi. PTA wastewater containing high COD (100000 to 150000 mg/L) was treated with coagulate ferrous ion and then was oxidized independently with aqueous hydrogen peroxide using different doses at 45 °C for 1h. The resulting wastewater was passed through RO plant equipped with high porosity bio-ceramic membrane. It was observed that coagulation and oxidation processes have potential to reduce 87.9% COD but complete reduction up to 99.8% was achieved after passing the effluents from high RO plant equipped with high porosity ceramic membrane.

A novel fast mass transfer anaerobic inner loop fluidized bed biofilm reactor for PTA wastewater treatment.

In this paper, a fast mass transfer anaerobic inner loop fluidized bed biofilm reactor (ILFBBR) was developed to improve purified terephthalic acid (PTA) wastewater treatment. The emphasis of this study was on the start-up mode of the anaerobic ILFBBR, the hydraulic loadings and the operation stability. The biological morphology of the anaerobic biofilm in the reactors was also analyzed. The anaerobic column could operate successfully for 46 days due to the pre-aerating process. The anaerobic column had the capacity to resist shock loadings and maintained a high stable chemical oxygen demand (COD) and terephthalic acid removal rates at a hydraulic retention time of 5-10 h, even under conditions of organic volumetric loadings as high as 28.8 kg COD·m(-3).d(-1). The scanning electron microscope analysis of the anaerobic carrier demonstrated that clusters of prokaryotes grew inside of pores and that the filaments generated by pre-aeration contributed to the anaerobic biofilm formation and stability.

Treatment of multicomponent aqueous solution of purified terephthalic acid wastewater by electrocoagulation process: Optimization of process and analysis of sludge

The present research work is based on degradation of major pollutants of purified terephthalic acid (PTA) wastewater by electrocoagulation (EC) process. Terephthalic acid (TPA), benzoic acid (BA) and para-toluic acid (p-TA) are the major pollutants of PTA wastewater. A central composite design (CCD) has been developed for maximum removal of TPA, BA, p-TA, COD and minimum consumption of energy. Effects of various process parameters viz. pH: (5–13), current density: (49.5–255.5 A/m2), supporting electrolyte concentration, NaCl: (0.25–2.25 g/L) and electrolysis time: (15–95 min) are studied on removal efficiencies of responses. Aluminium (Al) and iron (Fe) were selected as electrode materials. Maximum percentage removal of TPA: 56.21, 54.10; BA: 59.52, 53.84; p-TA: 45.71, 39.91, and COD: 49.91, 42.95 are achieved at optimum operating conditions by Al and Fe electrodes respectively. Operating cost of the process was calculated based on energy consumption, electrode consumption, sludge disposable, and transportation costs and found $13.64 and $14.46 per kg of COD removed by Al and Fe electrodes respectively. Sludge residues obtained after EC treatment at optimum operating conditions are analyzed by settling, sludge volume index (SVI), XRD, SEM/EDX, point of zero charge (PZC), FTIR and DGA/TGA.

Adsorption of Co(II) and Mn(II) ions from pure terephthalic acid wastewater onto Na-bentonite

AbstractRemoval of Co(II) and Mn(II) ions from the pure terephthalic acid (PTA) wastewater onto Na-bentonite has been investigated in this work. Batch experiments were performed to elucidate the effects of various parameters, such as dosage of adsorbent, temperature, and initial pH, on the adsorption process. It has been found that the simulated adsorption process of the pseudo-second-order kinetic model was in better agreement with experimental results than that of the pseudo-first-order and intra-particle diffusion kinetic models. Moreover, the adsorption experiments were conducted at four temperatures, which was 298.15, 308.15, 318.15, and 328.15 K, respectively, with the initial metal concentrations ranging from 30 to 120 mg L−1, so as to study the adsorption thermodynamics. Compared with the Freundlich and Dubinin–Radushkevich models, the Langmuir isotherm model agreed better with experimental data. The Gibb’s free energy change (ΔG), enthalpy change (ΔH), and entropy change (ΔS) of the adsorption pr...

Performance of a single chamber microbial fuel cell at different organic loads and pH values using purified terephthalic acid wastewater.

BackgroundPurified terephthalic acid (PTA) wastewater from a petrochemical complex was utilized as a fuel in the anode of a microbial fuel cell (MFC). Effects of two important parameters including different dilutions of the PTA wastewater and pH on the performance of the MFC were investigated.MethodsThe MFC used was a membrane-less single chamber consisted of a stainless steel mesh as anode electrode and a carbon cloth as cathode electrode. Both power density and current density were calculated based on the projected surface area of the cathode electrode. Power density curve method was used to specify maximum power density and internal resistance of the MFC.ResultsUsing 10-times, 4-times and 2-times diluted wastewater as well as the raw wastewater resulted in the maximum power density of 10.5, 43.3, 55.5 and 65.6 mW m−2, respectively. The difference between the power densities at two successive concentrations of the wastewater was considerable in the ohmic resistance zone. It was also observed that voltage vs. initial wastewater concentration follows a Monod-type equation at a specific external resistance in the ohmic zone.MFC performance at three different pH values (5.5, 7.0 and 8.5) was evaluated. The power generated at pH 8.5 was higher for 40% and 66% than that for pH 7.0 and pH 5.4, respectively.ConclusionsThe best performance of the examined MFC for industrial applications is achievable using the raw wastewater and under alkaline or neutralized condition.

Experimental and modeling study of pure terephthalic acid (PTA) wastewater transport in the vadose zone.

PTA wastewater discharged from a factory was selected as the research object in this project and CODcr was selected as the characteristic pollution factor. Static adsorption and soil column leaching experiments of silty clay and clayey soil were carried out to study the adsorption, bio-degradation and dispersion coefficient of CODcr in PTA wastewater. Hydrus-1D was used to build the convection-diffusion model to demonstrate the migration of PTA wastewater in the vadose zone. The results indicate that silty clay and clayey soil in the vadose zone can adsorb, degrade and impede the contaminants in PTA wastewater; however, the coefficient of adsorption and degradation were very low, they were down to 0.0002 L g(-1), 0.0003 L g(-1) and 0.0097 d(-1), 0.0077 d(-1) for silty clay and clayey soil, respectively. Under the virtual condition that, wastewater in the sewage pool is 5 m deep, CODcr concentration is 4000 mg L(-1), vadose zone is 21 m, PTA wastewater will reach the phreatic surface after 20.87 years. When wastewater in the sewage pool is 7 m with other conditions unchanged, after 17.18 years PTA wastewater will reach groundwater. The results show that there is a higher pollution risk for groundwater if we do not take any anti-seepage measures.