Chemical Wastewater Research Articles

Biosorption of Cu(II) Ions Using Living Microalgae Chlorella sp.: Effects of Microalgae Concentration, Salinity, and Light Color

Chemical industry wastewater containing metals must be treated so as not to threaten the environment or human life. One of the wastewater treatments is the biosorption process using living microalgae. Although living microalgae can provide

Preparation of Pb/biochar composite as particle electrode for three-dimensional electrochemical oxidation of chemical oxygen demand from chemical wastewater

Preparation of Pb/biochar composite as particle electrode for three-dimensional electrochemical oxidation of chemical oxygen demand from chemical wastewater

Деструкция фталевых кислот штаммом Paenarthrobacter sp. SA101, выделенным из сточных вод химического предприятия

Phthalic and terephthalic acids (PA and TPA) are widely used in the chemical industry as plasticizers, for the production of polymer materials, and therefore are common eco-pollutants. The ability of the strain Paenarthrobacter sp. SA101, isolated from a sample of a chemical plant wastewater (Perm), to growth on high concentrations of PA and TPA was studied. It was shown that strain SA101 is capable of efficient growth on these substrates at concentrations up to 20 g/l, which is shown for the representatives of the genus Paenarthrobacter for the first time. Higher strain growth parameters were recorded in media with PA, than in media with TPA: the maximum value of OD600 (1.64), the highest specific growth rate (0.073±0.003 h-1) and the shortest lag phase were observed in a medium with 10 g/l of PA. The highest specific growth rate (0.04±0.002 h‑1) and the maximum value of OD600 (1.6) were observed with 20 g/l of TPA, however, the lag phase of growth was longer than in the medium with 10 g/l of TPA. The strain SA101 was able to utilize 76% of PA in 39 hours and 74.2% of TPA in 71 hours of cultivation, when using these substrates at a concentration of 10 g/l. The cells of the strain SA101 contain a plasmid with a molecular weight of ~ 100 bp. The strain SA101 is promising for the development of biotechnological methods for cleaning phthalate-contaminated soils and industrial effluents.

Extraction selection and process optimization of phenol-containing wastewater from coal chemical industry

In order to efficiently remove phenolics from coal chemical wastewater, this study utilizes molecular simulation to determine the most effective extractant. And the extraction effect is verified through simulation results. The energy of hydrogen bonding dominates the extractant’s extraction ability. The interaction between phenols the and solvent was examined using molecular simulation calculations, and it was discovered that the strong H-bond interaction between the CYC/1-PA synergistic extractant and phenols produces outstanding extraction effects. The results of the full process simulation validation showed that the CYC/1-PA synergistic extractant could properly treat the wastewater.

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.

A highly hydrothermal stable copper-based catalyst for catalytic wet air oxidation of m-cresol in coal chemical wastewater

Catalytic wet air oxidation (CWAO) can degrade some refractory pollutants at a low cost to improve the biodegradability of wastewater. However, in the presence of high temperature and high pressure and strong oxidizing free radicals, the stability of catalysts is often insufficient, which has become a bottleneck in the application of CWAO. In this paper, a copper-based catalyst with excellent hydrothermal stability was designed and prepared. TiO2 with excellent stability was used as the carrier to ensure the long-term anchoring of copper and reduce the leaching of the catalyst. The one pot sol–gel method was used to ensure the super dispersion and uniform distribution of copper nanoparticles on the carrier, so as to ensure that more active centers could be retained in a longer period. Experiments show that the catalyst prepared by this method has good stability and catalytic activity, and the catalytic effect is not significantly reduced after 10 cycles of use. The oxidation degradation experiment of m-cresol with the strongest biological toxicity and the most difficult to degrade in coal chemical wastewater was carried out with this catalyst. The results showed that under the conditions of 140 °C, 2 MPa and 2 h, m-cresol with a concentration of up to 1000 mg·L−1 could be completely degraded, and the COD removal rate could reach 79.15%. The biological toxicity of wastewater was significantly reduced. The development of the catalyst system has greatly improved the feasibility of CWAO in the treatment of refractory wastewater such as coal chemical wastewater.

Research on advanced treatment of phenolic chemical wastewater and carbon replacement by the multi-layer biological activated carbon filter

After a series of biochemical processes, the wastewater engendered by the production of phenolic resin is ultimately left with a majority of difficult degradation organic matter. Most of these organic compounds are harmful to the water environment and require further advanced treatment before discharge. In this study, the original simple biological activated carbon (BAC) filter column device was improved. The new multi-layer BAC filter does not require backwash after improvement. The treatment efficiency of the multi-layer BAC filter was studied through long-term operation, and the variation of pollutants in the wastewater was analyzed. The results indicated that the multi-layer BAC filter could effectively remove hardly biodegradable organic matter, ammonium‑nitrogen (NH4+-N), and total nitrogen (TN), and its mechanism was mainly that hardly biodegradable organic matter and TN were removed by adsorption and biodegradation, while NH4+-N was only removed by microbial degradation. The pore-size distribution characteristics on the BAC surface were analyzed, and it was found that the adsorption and biodegradation reactions mainly occurred in the microporous region. The experiment on carbon replacement indicated that the service time of the BAC system could be prolonged by choosing the correct time of carbon replacement and adding the appropriate amount of microorganisms. Based on high-throughput sequencing, it was found that the microbial communities on BAC at the same height were significantly different before and after carbon replacement. The results of this paper are of some relevance for the upgrading of advanced treatment processes for chemical wastewater in practical engineering.

Influencing Factors and Kinetics of Modified Shell Powder/La-Fe-TiO2 Photocatalytic Degradation of Pyridine Wastewater.

Modified Shell Powder/La-Fe-TiO2 (La-Fe-TiO2@MSP) composites were fabricated using the sol-gel method and characterized by SEM, XRD, UV-vis DRS and photocurrent techniques, and their physicochemical and optical properties were analyzed. The effects of various factors on the photocatalytic degradation of pyridine and its reaction kinetics were investigated by batch experiments using pyridine, a typical nitrogen-containing heterocyclic compound in coal chemical wastewater, as the target removal species. The pyridine degradation rate of 80.23% was obtained for 800 mg/L composite solution by photocatalytic oxidation of 50 mg/L pyridine wastewater for 180 min at 35 °C, pH = 8 and light intensity of 560 W. The photocatalytic degradation performance was optimal. The quenching experiments determined that the active species of photodegradation were mainly hole and hydroxyl radicals, and the photocatalytic degradation mechanism was analyzed in this way.

Dinitrobutylphenol Removal from aqueous Environments by Synthesized magnetic particles from walnut hard-shell ash

<p>Dinitrobutylphenol is a toxic and resistant pollutant that pollutes the environment by producing toxins and chemical wastewater. Present paper aims to study the efficiency of the magnetic particles of walnut hard shell ash as a cheap and bi-compatible adsorbent for the removable of DNBP from aqueous environments. This study was conducted at laboratory scale and studied the most important parameters including contact time, pH, adsorbent dose, concentration of the pollutant and temperature on the efficiency of the process. Walnut hard shell ash was magnetized and its properties were studied using SEM, FTIR, XRD, and BET techniques. The fitness of the data was studied using Langmuir and Freundlich isotherms. Results showed that at pH=7, temperature 25°C , 700 mg of adsorbent, within 50 min, the removal efficiency of DNBP with the initial concentration of 20 mg reached 93%. The isotherm studies showed that this process with fitness coefficient of 99% conforms to Langmuir equation and it has higher conformity to maximum adsorption of 142.88 mg/g. Magnetic particles of walnut hard shell ashes as a natural bio-friendly and cheap adsorbent is able to efficiently remove DNBP as a toxic and persistent material from aqueous environments and industrial wastewaters.</p>

Study of energy scheduling and optimal cost management of a new structure CCHP system: A case study supplying energy for a chemical enterprise in Jiangsu Province

A new structure combined cooling, heating and power (CCHP) system integrating green power applying a control strategy based on a improved whale optimization algorithm is proposed in this paper. This paper fully considers the high energy demand and a large amount of waste heat in chemical enterprises. By absorbing chemical waste heating (mainly from chemical wastewater), coupling wind and photovoltaic equipment, adding cooling, heating, and electricity storage equipment, combined with an energy scheduling strategy, and an efficient CCHP energy system for the target enterprise is realized. The improved whale optimization algorithm is used to optimize cost management. The results show that after the optimization scheduling with the improved whale optimization algorithm, the CCHP system meets the energy demand with higher efficiency at a lower cost. In winter and summer, heat pump recycling chemical wastewater provides 15.4%–57.9% and 11.5%–62.9% of the heating load of the heating network. Meanwhile, the lithium bromide refrigerator in the cooling-net equipment provides an average cooling load of 6.25–58.4% and 7.01–16.64%.​ Finally, the improved whale optimization algorithm reduces the total cost by 2.4 % and 2.17 %.

Recovery of Acid and Alkaline from Industrial Saline Wastewater by Bipolar Membrane Electrodialysis under High-Chemical Oxygen Demand Concentration

Actual high saline wastewater containing concentrated organics and sodium chloride is a bioenergy and renewable resource. This study compared two different bipolar membrane electrodialysis membranes from two companies' stacks to recover HCl and NaOH from sodium chloride solution and actual chemical wastewater. The results demonstrated that the electrolysis rates were around 1.5 kg/m2h, the HCl and NaOH production rates were about 0.9 kg/m2h, energy consumption was in the range of 1.05-1.27 kWh/kg, and the economic benefits were above 1 yuan/h in BMED systems. From analyzing the performance of seven different BMED membrane stacks, the B2 stack was chosen for electrolyzing actual high salt wastewater to observe the effect of chemical oxygen demand on BMED systems, where electrolytic salt performance, HCl-NaOH alkali production rates, and energy consumption show linear dependence on time for 5000 mg/L chemical oxygen demand wastewater. It illustrated chemical oxygen demand can enhance energy consumption and reduce electrolytic salt performance and the acid and alkali production rates, due to improving the membrane area resistance. In this study, the effect of high COD saline wastewater on the performance of a BMED membrane stack was clarified and the mechanism was analyzed for its practical application in treating chemical high salt wastewater.

A novel membrane photo-electro oxidizer for advanced treatment of coal processing wastewater: Fouling control and permeate quality

This study proposed and evaluated, for the first time, a novel membrane-photo-electrochemical oxidation (MPEO) process combining electrochemical oxidation, UV irradiation, and ceramic microfiltration for the advanced treatment of coal processing wastewater. The MPEO process could achieve 600 h of sustainable and continuous operation with excellent color (∼90%) and turbidity (>90%) removal. Without electrochemical oxidation and UV irradiation, severe membrane fouling was observed during direct microfiltration due to the accumulation of high content of polysaccharides, proteins and humic-like substances contained in the feedwater on the membrane. On the other hand, in the MPEO system, these macro-organic molecules were effectively degraded into small molecules by the highly reactive hydroxyl free radical (∙OH) produced from electrochemical oxidation and UV irradiation. FT-ICR-MS analysis confirmed these results and showed a significant increase in the number of small organic molecules after MPEO treatment. The MPEO system in this study could potentially be an efficient and sustainable treatment process for treating chemical industrial wastewater containing refractory organics.

Characterisation of aluminium industrial wastewater and investigation of recovery alternatives

Aluminium industry is one of the largest sectors and wastewater generated from this industry could cause crucial environmental problems due to its high heavy metal concentration and conductivity. Therefore, this study aims to determine the characterisation of the wastewater discharged from the two aluminium facilities by considering water recovery potential. While Facility-A produces stainless steel kitchenware, such as pots and pans, In Facility-B, anodised coating takes place from secondary aluminium and wastewater is generated from the units where anodised coating baths and control processes are carried out. For the analyses, the wastewater composite samples from different sections, such as washing, sand-blasting and dyeing in Facility-A were taken in 2 and 24 hours. In Facility-B, three 2-hour composite influent water samples and an effluent sample from chemical wastewater treatment were taken to determine conductivity, pH, chemical oxygen demand (COD), total suspended solids (TSS), etc. As a result of the analyses made, a high value of TSS was detected at all sampling points in Facility-A. It was also seen that the conductivity after demineralisation process in Facility-A was below 30. In Facility-B, it was determined that while the pH obtained from two influent samples was below the discharge limits and showed acidic characteristics, one sample was very basic with a pH value of 12.19 and exceeds the upper limit of discharge. All influent samples in Facility-B show high TSS content in comparison with discharge limits specified in the regulation.

Scaling trend of coal chemical saline wastewater in falling film evaporator: experimental solid–liquid equilibrium and numerical simulation

Abstract It was important to establish the scaling mechanism to slow down scaling, which is one of the important problems faced by saline wastewater treatment with falling film evaporators. In this paper, the phase equilibrium data of ternary system NaCl-CaCl2-H2O at 303.15–373.15 K were measured, and the prediction of the flow characteristics and scaling tendency of salt-containing wastewater in the evaporation tube was investigated by numerical simulation based on the phase equilibrium results. The results showed that the mesostable phase diagram of the ternary system was of simple type, and w(NaCl) and w(CaCl2) showed regular variation with temperature when w(NaCl) in the system was 15–28%. Moreover, the components of the four saline wastewaters (10% NaCl + 9, 10, 11, 12% CaCl2) with less salt content had a faster heating and a faster rate of evaporation of the liquid film in the evaporation tube. Based on the solubility in the experiments and simulations, it was concluded that NaCl crystals were precipitated at tube lengths of 718 mm, 942 mm, 966 mm, and 1,000 mm for four salt concentrations in the evaporation process by comparison, and the reliability of the predicted loci was also demonstrated by a falling film evaporation experimental setup.

Competing contributions to the catalytic activity of barium titanate nanoparticles in the decomposition of organic pollutants

There is an increasing demand for innovative solutions to protect the environment from different kinds of industrial pollutants and to complement the existing physical, chemical and biological wastewater treatment techniques. Recently, the use of piezoelectric nanomaterials as catalysts for water purification has been suggested. We show that the observed catalytic activity may not be entirely attributed to the piezoelectric effect of nanomaterials. While piezoelectric-based catalysis has already been studied using several piezoelectric materials, its discrimination against the omnipresent tribocatalysis or sonocatalysis remains in its infancy thus questioning the relevance of the additional piezoelectric contribution. In this study, we investigate the catalytic activities of both piezoelectric barium titanate (BaTiO3) and non-piezoelectric titanium dioxide (TiO2) to distinguish between sono- tribo- and piezocatalytic contributions. Comparing the catalytic performance of BaTiO3 and TiO2 for different concentrations and temperatures gives an approach to better understand the contribution of different physical effects to the catalytic activity of BaTiO3. It is shown that for otherwise identical properties such as size, crystallinity and similar properties of surface terminations, the comparison of TiO2 and BaTiO3 yields a contribution of around 90 % to the piezoelectric effect in the BaTiO3 catalytic response.

An efficient electrodialysis metathesis route to recover concentrated NaOH-NH4Cl products from simulated ammonia and saline wastewater in coal chemical industry

Coal chemical industry typically generated a series of wastewater such as ammonia wastewater and saline wastewater. The inappropriate treatment of these systems not only induced serious water pollution but caused waste of resources. To solve this situation, an efficient electrodialysis metathesis (EDM) route was proposed to transform simulated ammonia wastewater and saline wastewater into concentrated NaOH and NH4Cl products with higher added values. During the EDM processes, the influence of operating voltage, simulated ammonia wastewater circulating flow rate and feeding rate was explored and the optimal condition was determined. Under this condition, the NaOH and NH4Cl products were concentrated to 1.63 mol/L and 1.85 mol/L with purity at 80.71 wt% and 90.40 wt%, respectively. To further reveal the process mechanism, the ions especially OH− migration were systematically analyzed. It was found that the rejection rate of cation exchange membrane (CEM) towards OH−, dissociation of ammonia and intrinsic water migration were the three main factors dominating the concentration and purity of the final products. This work could provide potential directions for both high-value resources recycling and treatment of coal chemical industrial wastewater.

Advanced technique of catalytic ozonation-enhanced coagulation for the efficient removal of low coagulability refractory organics from secondary effluent.

The novel cascaded catalytic ozonation-enhanced coagulation process (FeCeAC/O3-PAC) was developed with much success towards second effluent organic matter (EfOM) in chemical industrial wastewater. Compared with the conventional techniques, FeCeAC/O3-PAC exhibited remarkable performances in the advanced removal of EfOM. The characteristics of EfOM and interactivities of reaction process played the crucial roles. Especially, the removal rate constant of soluble microbial products (SMPs) with FeCeAC/O3-PAC exceeded 55.38% versus FeCeAC/O3. The outstanding synergistic effect was contributed to the enhanced generation of active oxygen species by FeCeAC and PAC, which increased the content of oxygen-containing functional groups of EfOM and thus facilitated the interaction between PAC and EfOM. As the result, the larger-sized flocs could be formed and separated easily. Herein, this work found a far more effective way to remove EfOM especially low-coagulability refractory organics (LCRO) in chemical sewage plant.

Roles of Fe-C amendment on sulfate-containing pharmaceutical wastewater anaerobic treatment: Microbial community and sulfur metabolism.

The effects of multiple two-phase anaerobic treatment involving acidification coupling Fe-C on sulfate-containing chemical synthesis-based pharmaceutical wastewater treatment were investigated. Fe-C was added as a filler with 25% vol. to acidogenic reactors for semi-continuous operation. The results suggested that Fe-C amendment promoted sulfate removal efficiency by 47.5% and shortened the reaction time by 50% in the acidogenic phase. With mitigation of sulfate inhibition, SCOD removal efficiency and methane production were further increased by 24.6% and 398% compared to direct raw wastewater anaerobic digestion, respectively, in methanogenic phase. The results of sulfate removal kinetics confirmed a 150% increase of removal rate in acidogenic phase. However, the apparent kinetic microbial sulfate removal constant without Fe-C amendment was maintained at approximately 0.06 h-1. The Fe-C amendment not only increased the relative abundance of Methanothrix and Desulfovibrio for sulfate reduction but also enriched unclassified_p__Chloroflexi and unclassified_c__Deltaproteobacteria for acidification. Metagenomic results indicated that Fe-C enhanced dissimilatory sulfate reduction and PAPS synthesis of assimilatory step. The hydrogen sulfide production through the 3-mercaptopyruvate to pyruvate pathways was also enhanced. Butyrate-oxidizing genes were increased synchronously to convert butyrate to acetate.

Preparation of Mn/Zn@PG Catalyst for Catalytic Oxidation Treatment of Coal Chemical Wastewater.

In this study, Mn/Zn@palygorskite (PG) catalysts with developed pores and good salt tolerance were prepared and applied to the treatment of coal chemical wastewater. A doping ratio of metal elements, calcination temperature, and calcination time was used to optimize the preparation conditions and determine the optimal preparation conditions of the Mn/Zn@PG catalysts. The catalysts, obtained under various preparation conditions, were characterized and analyzed by XRD, SEM, EDS, BET, XRF, XPS, and other techniques. Results showed that the Zn and Mn elements in the Mn/Zn@PG catalyst existed as ZnO and MnO2, respectively. The optimal working conditions of the Mn/Zn@PG catalyst for catalytic oxidation treatment of coal chemical wastewater, obtained through the optimization of working conditions, are the following: reaction time 60 min, wastewater pH = 9.28, ozone ventilation rate 0.2 L/min, catalyst filling ratio 20%. The height-to-diameter ratio of the tower was 6:1. The abrasion resistance and catalytic performance of the Mn/Zn@PG catalyst after repeated use were investigated, and the mechanism of the loss of active components of the Mn/Zn@PG catalyst was explored. The coal chemical wastewater, before and after treatment, was analyzed by UV–vis spectroscopy and 3D fluorescence spectroscopy. The hierarchical–principal component comprehensive evaluation system (AHP–PCA) was established to evaluate the catalytic ozonation process of coal chemical wastewater, so that the overall evaluation of the process performance can be achieved.

Prospective life cycle assessment of a bioprocess design for cultured meat production in hollow fiber bioreactors

The aim of cellular agriculture is to use cell-culturing technologies to produce alternatives to agricultural products. Cultured meat is an example of a cellular agriculture product, made by using tissue engineering methods. This study aims to improve the understanding of the potential environmental impacts of cultured meat production by comparing between different bioprocess design scenarios. This was done by carrying out a life cycle assessment (LCA) for a bioprocess system using hollow fiber bioreactors, and utilizing bench-scale experimental data for C2C12 cell proliferation, differentiation and media metabolism. Scenario and sensitivity analyses were used to test the impact of changes in the system design, data sources, and LCA methods on the results to support process design decision making. We compared alternative scenarios to a baseline of C2C12 cells cultured in hollow fiber bioreactors using media consisting of DMEM with serum, for a 16-day proliferation stage and 7-day differentiation stage. The baseline LCA used the average UK electricity mix as the energy source, and heat treatment for wastewater sterilization. The greatest reduction in environmental impacts were achieved with the scenarios using CHO cell metabolism instead of C2C12 cell metabolisim (64–67 % reduction); achieving 128 % cell biomass increase during differentiation instead of no increase (42–56 % reduction); using wind electricity instead of average UK electricity (6–39 % reduction); and adjusting the amino acid use based on experimental data (16–27 % reduction). The use of chemical wastewater treatment instead of heat treatment increased all environmental impacts, except energy demand, by 1–16 %. This study provides valuable insights for the cultured meat field to understand the effects of different process design scenarios on environmental impacts, and therefore provides a framework for deciding where to focus development efforts for improving the environmental performance of the production system.