Chemical Oxygen Demand Removal Rate Research Articles

High-performance loose nanofiltration membrane prepared with assembly of covalently cross-linked polyethyleneimine-based polyelectrolytes for textile wastewater treatment

• High-flux loose NF membrane prepared by assembly of branched PEI and PEI-PO 3 Na. • Cross-linkable PEI and PEI-PO 3 Na enable the good stability of the membrane. • Chelatable phosphonate groups in PEI-PO 3 Na lower the membrane scaling tendency. • Membrane properties are optimizable by varying Mw of PEI-PO 3 Na. • Great potential for actual textile wastewater treatment is expected. Conventional nanofiltration membrane with high rejections to both dyes and inorganic salts are not suitable for the treatment of the textile wastewater. Herein, novel loose nanofiltration membranes were fabricated by the assembly of polyethyleneimine (PEI) and phosphorylated PEI (PEI-PO 3 Na) coupled with glutaraldehyde crosslinking. The PEI-based polyelectrolytes with branched structures and plentiful amine crosslinking sites enabled the formation of a highly permeable and robust selective layer. Meanwhile, the introduced phosphonate groups endowed the membrane with anti-fouling and anti-scaling properties owing to their surface hydrophilicity and chelation ability. By varying the molecular weight of PEI-PO 3 Na, the surface properties, pore size, and selective layer thickness and corresponding performances of the resultant PEI-PO 3 Na/PEI membranes can be successfully manipulated. The PEI-PO 3 Na 10 k/PEI membrane showed a high permeability (24.2 LMH/bar), high Victoria blue BO (99.5%) but low NaCl rejection (10.1%), demonstrating the best dye/salt fractionation performance. While PEI-PO 3 Na 70 k/PEI membrane exhibited the highest chroma and chemical oxygen demand (COD) removal rates, and the best anti-fouling ability for the textile wastewater treatment. The PEI-PO 3 Na/PEI membrane also exhibited good stability in various pH, and relatively low scaling propensity. This work provides a facile and convenient method for fabricating high-performance loose NF membranes for the practical textile wastewater treatment.

Removal of Bentazone Pesticide from Aqueous Solutions by Electro-oxidation Method

The kinetics of the electro-oxidation degradation of prepared aqueous solutions containing bentazone as a model compound of the thiadiazine group of pesticides was studied in the lab. The oxidation process was conducted under galvanostatic polarization in natural model media using boron-doped diamond (BDD) cathode and anode. Chemical oxygen demand (COD) estimation along the electro-oxidation treatment processing allowed the assessment of kinetic of organic compounds decay as well as the instantaneous current efficiency. The obtained data reflected that the degradation of bentazone pesticide is significantly dependent on initial amount of bentazone pesticide, current density and electrolytes concentration. COD removal follows a pseudo first-order kinetic and the electro-oxidation process was under the control of mass transport within the range studied, regardless the conditions of experimental. The COD removal rate increases with applied current density until 20 mA/cm2 and decreases for higher values. Two different concentrations supporting electrolyte (5mM, 10mM) were used. The rate of degradation increased significantly with increasing electrolyte concentration. The best obtained conditions for COD removal efficiency on the BDD electrode to degrade bentazone solutions (COD= 91.18 %) include operating at 20 mA/cm2 and 10 mM Na2SO4 as supporting electrolyte. This arrangement and condition allow to approximately complete degradation of bentazone in just 80 min. A decrease in the relative toxicity index value along the electro-oxidation indicate toxic compounds disappearance. The initial toxicity EC50 (5 min) and (15min) were decrease by 81% and 94% The kinetics of the electrooxidation degradation of prepared aqueous solutions containing bentazone as a model compound of the thiadiazine group of pesticides were studied in the lab. The oxidation process was conducted under galvanostatic polarization in natural model media using boron-doped diamond (BDD) cathodes and anode. Chemical oxygen demand (COD) estimation along the electro-oxidation treatment processing allowed the assessment of kinetic of organic compounds decay as well as the instantaneous current efficiency. The obtained data reflected that the degradation of bentazone pesticide is significantly dependent on initial amount of bentazone pesticide, current density and electrolytes concentration. COD removal follows a pseudo first-order kinetic and the electrooxidation process was under the control of mass transport within the range studied, regardless the conditions of experimental. The COD removal rate increases with applied current density until 20 mA/cm2 and decreases for higher values. Two different concentration (5mM, 10mM) were used. The rate of degradation increased significantly with increasing electrolyte concentration. The best obtained conditions for COD removal efficiency on the BDD electrode to degrade bentazone solutions (COD= 91.18 %) include operating at 20 mA/cm2 and 10 mM. This arrangement and condition allow to approximately complete degradation of bentazone in just 80 min. A decrease in the value of  relative toxicity index along the electrolysis indicate the disappearance of toxic compounds. The initial toxicity EC50 (5min) and (15min) were reduced by 81% and94% respectively after 80 minutes.

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.

Feasibility assessment of oil sands process water treatment in a flow‐through microbial electrolysis cell

This study examines the feasibility of oil sands process water (OSPW) treatment in a gravitational flow-through membraneless microbial electrolysis cell (MEC) using crushed metallurgical coke as an electrode material. Synthetic OSPW was composed of the water soluble fraction (WSF) of diesel, naphthenic acids (NAs), and metals with a total chemical oxygen demand (COD) concentration of 200 mg L − 1 and total NA concentration of 9.4 mg L − 1. OSPW treatment under bioelectrochemical conditions (1.4 V applied voltage) was compared with a control system operated at 0 V. Furthermore, in an additional set of experiments, microaerobic conditions were applied to both MEC and control setups to facilitate NA biodegradation. Highest NA and COD removal rates were observed in the MEC with microaeration in electrode compartments, where total NA concentration decreased to 4.2 mg L − 1 at a hydraulic retention time of 4 days. Furthermore, microtox and microalgae toxicological assays showed substantial toxicity decrease in this MEC.

Effect of Chemical Oxygen Demand Concentration on Nutrient Removal in Simultaneous Nitrification, Denitrification and Phosphorus Removal System in High-Altitude Areas

The application of biological nitrogen and phosphorus removal processes in high-altitude areas faces severe challenges due to low temperature, low atmosphere pressure and low oxygen concentration. In this study, a simultaneous nitrification, denitrification and phosphorus removal (SNDPR) system was operated under low atmosphere pressure. The chemical oxygen demand (COD) concentrations in influent were decreased from 300 mg/L (stage I) to 200 mg/L (stage II), corresponding to the low COD concentration of sewage in high-altitude areas. The removal of COD and total phosphate was efficient at the H1 reactor (72 kPa). The removal rates of COD and total phosphate were 94.08% (stage I), 90.66% (stage II) and 98.43% (stage I), 99.34% (stage II), respectively, which were similar to L1 (100 kPa). The removal rates of total inorganic nitrogen and simulation nitrification and denitrification were from 81.21% (stage I) and 59.48% (stage I) to 72.86% (stage II) and 31.95% (stage II), respectively, which were also improved compared to L1. Cycle experiment results indicated that the activity of phosphorus accumulating organisms was enhanced, while the ammonia oxidation process was inhibited under low atmosphere pressure.

The degradation and simultaneous influence of bisphenol A on methane production in a bio-anode single-chamber microbial electrolysis cell

The objective of this research was to estimate the effect of operational parameters on the performance of a bio-anode single-chamber microbial electrolysis cell (BSMEC) in degradation of bisphenol A (BPA) and simultaneous production of methane. To achieve this purpose, the influence of various parameters such as hydraulic retention time (HRT), applied voltage, C/N ratio and concentration of the BPA was examined on the performance of BSMEC during a 150-day period. According to the results, the BSMEC attained a BPA removal of 95.4%, a chemical oxygen demand (COD) removal rate of 94.9%, a methane production rate of 121.4 ± 2.2 mL/L.day and a methane content of 91.9% which were higher than these of the control system with 54.2%, 61.3% and 83.1 ± 2.2 mL/L.day and 71.1% respectively, at optimum condition (HRT=24 h, applied voltage=0.8 V, C/N ratio = 50 and BPA concentration = 10 mg/L). Our finding indicated that degradation of BPA, COD removal rate, methane production rate and methane content were improved as C/N ratio increased from 20 to 50. In the BSMEC, maximum energy efficiency was in the range of 93.1–96.8% with an average of 95.7%. As a result, the BSMEC is a promising alternative not only to degrade the endocrine disrupting compounds (EDCs) but also to generate the methane.

Application of sequencing batch biofilm reactor (SBBR) to recycled paper mill effluent treatment

Abstract Paper mill effluent has been characterized as recalcitrant because of containing lignin and its derivatives. Since biofilm system exhibits a notable potential for the removal of recalcitrant contaminants, a sequencing batch biofilm reactor (SBBR) was employed to treat coagulated recycled paper mill effluent in this study. The results indicated that the SBBR removed 91.3 % of chemical oxygen demand (COD), whilst total suspended solid (TSS) and color removal reached 83.1 % and 71.0 %, respectively. The microbial analysis suggested that three typical heterotrophic phyla, Proteobacteria, Bacteroidetes and Acidobacteria are dominant bacteria and reflected the removal of recalcitrant contaminants. The COD removal rate of SBBR is evidently superior to conventional activated sludge process due to high sludge concentration as well as long sludge retention time (SRT). Whilst the problem of sludge bulking can be successfully avoided, the blockage of reactor caused by TSS accumulation and microbial growth deserve further investigation.

Fabricating novel PVDF-g-IBMA copolymer hydrophilic ultrafiltration membrane for treating papermaking wastewater with good antifouling property.

Ultrafiltration membranes are widely used for the treatment of papermaking wastewater. The antifouling performance of polyvinylidene fluoride (PVDF) ultrafiltration membranes can be improved by changing the hydrophilicity. Here, a novel amphiphilic copolymer material, PVDF grafted with N-isobutoxy methacrylamide (PVDF-g-IBMA), was prepared using ultraviolet-induced Cu(II)-mediated reversible deactivation radical polymerization. The amphipathic copolymer was used to prepare ultrafiltration membrane via NIPS. The prepared PVDF-g-IBMA ultrafiltration membrane was estimated using 1H NMR, FT-IR, and DSC. The contact angle, casting viscosity, and the permeation performance of the PVDF-g-IBMA ultrafiltration membrane were also determined. The pure water flux, bovine serum albumin removal rate, and pure water flux recovery rate of the PVDF-g-IBMA ultrafiltration membrane were 432.8 L·m-2·h-1, 88.4%, and 90.8%, respectively. Furthermore, for the treatment of actual papermaking wastewater, the chemical oxygen demand and turbidity removal rates of the membrane were 61.5% and 92.8%, respectively. The PVDF-g-IBMA amphiphilic copolymer ultrafiltration membrane exhibited good hydrophilicity and antifouling properties, indicating its potential for treating papermaking wastewater.

Enhanced bioelectrochemical nitrogen removal in flow through electrodes

In the past decade, bioelectrochemical systems (BESs) have been studied extensively for the generation of power and maximizing power densities. In recent years, it was noticed that BESs applications can critically improve wastewater treatment. Most of the previous BESs work has used varied reactor geometry and configuration, wastewater composition, electrolyte solution, and constant electrode size to maximize power generation. However, there is limited research investigating the influence of increased electrode size on the wastewater treatment process. We investigated the effect of increased electrode surface area on wastewater treatment efficiency and studied the mechanism of nitrogen removal. In this study, we developed a flow-through electrode in a 3-electrode bioelectrochemical reactor. The anodic biofilms were enriched on electrodes for one week. Following the anodic enrichment period, the reactor was operated in a semi-continuous mode with raw domestic wastewater. To investigate the wastewater treatment efficiency, the chemical oxygen demand (COD), total nitrogen (TN), ammonia (NH3-N), nitrite (NO2–-N), and nitrate (NO3–-N) concentrations were measured. We found that increased surface area of anode did not significantly contribute to COD removal rate, most likely indicating the limits of BES. On the other hand, the TN removal rate increased proportionally to the surface area of the anode in the BES. We also found that outlet NO3–-N and NO2–-N concentrations were 1.2 ± 0.2 and 3.2 ± 0.9 mg/L, respectively. Our results indicated that it is possible to remove COD and TN simultaneously. Analysis of the microbial community structure showed that nitrogen removal was dominated by sulfidogenesis, anodic ammonia oxidation, autotrophic and heterotrophic denitrification as well as reducing NO3–-N to NO2–-N usingGeobacterspecies in our system.

Use of combined UASB + eMBR treatment for removal of emerging micropollutants and reduction of fouling

Abstract This study employs a novel combined pilot plant consisting of an anaerobic reactor followed by a membrane electrochemical bioreactor (eMBR) to treat domestic water containing selected contaminants of emerging concern (CECs) [ibuprofen (IB), carbamazepine (CBZ), diclofenac (DCF) and 17α-ethinylestradiol (EE2)]. The first phase operated as a conventional membrane bioreactor to achieve the removal of organic matter [chemical oxygen demand (COD)], the CECs and phosphorus. A removal rate of 96.3% for COD, 94.5% for IB, 37.1% for CBZ, 87.1% for DCF and 96% for EE2 was obtained. In the three subsequent phases, current density (CD) of 5, 10 and 15 A/m2 was applied successively in the eMBR with the aim of investigating the effects on the removal of the former components and the fouling of the membrane. After the application of 5 and 10 A/m2 CD, the removal rate of COD decreased. Regarding phosphorus, a CD of 5 A/m2 was enough to achieve the rate of 97% and the membrane fouling suffered a substantial reduction too. Finally, the experimental results were subject to statistical analysis using the Kruskal–Wallis and Wilcoxon tests to validate the influence of each CD.

Facile synthesis of nitrogen and sulfur co-doped hollow microsphere polymers from benzothiazole containing wastewater for water treatment

Advanced oxidation is a very efficient method in wastewater treatment, but it is a waste of resources to directly oxide the high concentration of valuable organics into carbon dioxide and water. In this paper, the combination of persulfate and wet air oxidation was developed to recover organics from high concentration of wastewater, along with high mineralization of the residual organics. Nitrogen and sulfur co-doped hollow spherical polymers with narrow size distribution was recovered from the simulated benzothialzole (BTH) wastewater in this facile way, along with chemical oxygen demand (COD) removal rate higher than 90%. The formation route of the polymers was intensively studied based on detailed analysis of different kinds of reaction intermediates. The polymers can be further carbonized into co-doped hollow carbon microsphere, which showed better performance in organic contaminants removal than a commercial activated carbon both in adsorption or catalytic persulfate oxidation. This proposed a new strategy to simultaneously combine oxidation and polymerization for resource recovery from wastewater with high concentration of heterocyclic compounds.

Sulfate removal performance and co-occurrence patterns of microbial community in constructed wetlands treating saline wastewater

The migration and transformation of sulfur is closely related to carbon sources. However, knowledge on the co-occurrence patterns of sulfur-related bacteria and other carbon-consuming microorganisms in constructed wetlands (CWs) is limited. In this study, CWs with intertidal wetland sediments (IWS), as microbial inoculant, was constructed to investigate the sulfate and chemical oxygen demand (COD) removal rates, microbial community composition, and co-occurrence network. IWS-enhanced CWs planted with Phragmites australis (PA+) and unplanted ones (CT+) were set up with controls (PA and CT). Results showed that the sulfate removal rate was higher in PA+ (60.60% ± 0.80%) than PA (44.64% ± 2.72%). The sulfate removal rate decreased and that of COD increased in PA+ and PA when the influent sulfate concentrations were raised. Microbial analysis indicated that the numbers of sulfate-reducing bacteria (SRB), sulfur oxidizing bacteria (SOB), and carbon-degrading bacteria improved the removal efficiency of sulfate in PA+ and CT+. The microbial topological pattern revealed that the exchange of matter, energy, and information by microorganisms in PA+ and CT+ was faster than that in PA and CT. The co-occurrence network analysis indicated that SRB (e.g., unclassified Desulfuromonadaceae) harbored negative correlations with denitrifying bacteria (e.g., Thauera, Flavobacterium, and unclassified Burkholderiaceae) because of electron donor competition. However, Flavobacterium and Thauera could cooperate to denitrify through different electron donors to avoid competition. Moreover, Pseudomonas and Amaricoccus had cross-feeding and cooperation in the network when carbon was restricted.

Performance of anode materials in electrochemical treatment system for indigo dyeing wastewater

PurposeThis study aims to explore suitable anode materials used in the electrochemical system for indigo dyeing wastewater, to achieve optimal treatment performances.Design/methodology/approachThe single factor experiment was used to explore the optimum process parameters for electrochemical decolorization of indigo dyeing wastewater by changing the applied voltage, electrolysis time and electrolyte concentration. At the voltage of 9 V, the morphology of flocs with different electrolytic times was observed and the effect of electrolyte concentration on decolorization rate in two electrolyte systems was also investigated. Further analysis of chemical oxygen demand (COD) removal rate, anode weight loss and sediment quantity after electrochemical treatment of indigo dyeing wastewater were carried out.FindingsComprehensive considering the decolorization degree and COD removal rate of the wastewater, the aluminum electrode showed the best treatment effect among several common anode materials. With aluminum electrode as an anode, under conditions of applied voltage of 9 V, electrolysis time of 40 min and sodium sulfate concentration of 6 g/L, the decolorization percentage obtained was of 94.59% and the COD removal rate reached at 84.53%.Research limitations/implicationsIn the electrochemical treatment of indigo dyeing wastewater, the aluminum electrode was found as an ideal anode material, which provided a reference for the choice of anodes. The electrodes used in this study were homogenous material and the composite material anode needed to be further researched.Practical implicationsIt provided an effective and practical anode material choice for electrochemical degradation of indigo dyeing wastewater.Originality/valueCombined with the influence of applied voltage, electrolysis time and electrolyte concentration and anode materials on decolorization degree and COD removal rate of indigo dyeing wastewater, providing a better electrochemical treatment system for dyehouse effluent.

Competence of Lepironia articulata in eradicating chemical oxygen demand and ammoniacal nitrogen in coffee processing mill effluent and its potential as green straw

Phytoremediation is an environmentally friendly technique in wastewater treatment because of its sustainability, cost-effectiveness, and simplicity. This study was conducted to examine the feasibility of use of Lepironia articulata, a potential phytoremediation plant that is native to Malaysia, in remediating coffee processing mill effluent (CPME). The aim was to determine effluent concentration or contaminant load that the plant can resist, while simultaneously results in the good removal of pollutants during phytoremediation. Four brushes of L. articulata were planted individually in a pail/reactor (mentioned as reactor afterward) containing 3 kg of sand and exposed to five different concentrations of CPME (0%, 30%, 50%, 75%, and 100%). The initial chemical oxygen demand (COD) values were 510, 3100, 4200, 7290, and 8470 mg/L, respectively, and ammoniacal nitrogen (AN) concentrations were 26, 128, 225, 376, and 509 mg/L, respectively. The height, appearance, and efficiency in removing COD and AN of each plant was observed throughout the 35-day exposure period. Results showed that plants exposed to 75% CPME demonstrated better growth than those exposed to other concentrations and exhibited the highest COD and AN removal rates (85.0% and 84.0%, respectively), providing evidence that L. articulata can be used as a phytoremediation agent of CPME with an initial COD concentration of 7290 mg/L and AN concentration of 376 mg/L. This study highlights its support to the Sustainable Development Goals adopted by the United Nations, particularly the reclamation of plant biomass used as a treatment agent and conversion into biodegradable straws. Moreover, this study adds an attractive additional point of transforming waste into resource with the proposed wastewater treatment technology.

Bifunctional Fe for Induced Graphitization and Catalytic Ozonation Based on a Fe/N-Doped Carbon-Al2O3 Framework: Theoretical Calculations Guided Catalyst Design and Optimization.

Heterogeneous catalytic ozonation is regarded as a feasible technology in advanced wastewater treatment. Catalytic performance, mass transfer, and mechanical strength are the key elements for large-scale applications of catalysts. To optimize those elements, Fe was selected for its dual role in graphitization and catalytic ozonation. A Fe/N-doped micron-scale carbon-Al2O3 framework (CAF) was designed and applied to a fluidized catalytic process for the treatment of secondary effluent from coal gasification. The chemical oxygen demand removal rate constant and the hydroxyl radical generation efficiency (Rct) of the Fe/N-doped CAF were 190% and 429% higher than those of pure ozone, respectively. Theoretical calculations revealed that higher Fe valence promoted ozone decomposition, which implied increasing FeIII content for further catalyst optimization. The rate constant and Rct with a higher FeIII-proportion catalyst were increased by 13% and 16%, respectively, compared to those with the lower one. Molecular dynamics and density functional theory calculations were performed to analyze the reaction kinetics qualitatively and quantitatively. The energy barrier corresponding to FeIII configuration was 1.32 kcal mol-1, 27% lower than that for FeII configuration. These theoretical calculations guided the catalyst optimization and provided a novel solution for designing ozonation catalysts. The Fe/N-doped CAF demonstrated a great potential for practical applications.

Coconut-shell-derived bio-based carbon enhanced microbial electrolysis cells for upgrading anaerobic co-digestion of cow manure and aloe peel waste

Microbial electrolysis cells (MECs) and exogenous accelerants can augment anaerobic digestion performance. Herein, MECs and coconut-shell-derived bio-based carbon (CBC) accelerant are adopted to strengthen anaerobic co-digestion of cow manure and aloe peel waste. The MEC with the voltage of 0.6 V and CBC accelerant of 0.15 wt.% gained the highest cumulative biogas yield (444.20 NmL/g VS) and chemical oxygen demand removal rate (75.46%), which are 80.25% and 58.33% higher than those (246.44 NmL/g VS, 47.66%) of the blank group, respectively. The digestates embodied a utilization potential with thermogravimetric loss of 37.12%–50.67% and total nutrient content of 35.36–51.58 g/kg. These results benefited from excellent electrocatalytic activity of MECs and physicochemical properties of CBC accelerant. A general strategy for understanding improved methanogenesis was proposed based on integrated effects of MECs and CBC accelerant. This work will shed light on development of anaerobic co-digestion by combining MECs and bio-based carbon accelerants.

Hydrothermal liquefaction aqueous phase treatment and hydrogen production using electro-oxidation

Post-hydrothermal liquefaction (HTL) aqueous phase treatment is an emerging issue and must be addressed for the commercial application of the HTL process. This study investigates the simultaneous production of hydrogen and reduction of chemical oxygen demand by applying electro-oxidation using boron doped diamond electrodes. Two types of hydrothermal liquefaction aqueous phases produced from wheat straw and sewage sludge are investigated and the largest chemical oxygen demand removal (82 and 99%) and hydrogen production rates (2.0 and 1.8 NL/h) were attained at the highest current density. However, a positive energy return on investment of an integrated HTL-electro oxidation process can only be achieved at the lowest current density where the removal of organics and hydrogen production is lower. Analysis via GC–MS and GC-FID shows that complex aromatic compounds are degraded first through the formation of organic acids that are oxidized only with longer residence times and more severe current densities.

Bioaugmentation Technology for Treatment of Toxic and Refractory Organic Waste Water Based on Artificial Intelligence.

With the development of modern chemical synthesis technology, toxic and harmful compounds increase sharply. In order to improve the removal efficiency of refractory organic matter in waste water, the method of adding powdered activated carbon (PAC) to the system for adsorption was adopted. Through the analysis of organic matter removal rule before and after waste water treatment, it can be found that PAC is easy to adsorb hydrophobic organic matter, while activated sludge is easy to remove hydrophilic and weakly hydrophobic neutral organic matter. Powdered activated carbon-activated sludge SBR system (PAC-AS) system is obviously superior to AS and PAC system in removing organic matter of hydrophilic and hydrophobic components, that is, biodegradation and PAC adsorption are additive. Compared with the control system, the Chemical Oxygen Demand (COD) removal rate of refractory substances increased by 8.36%, and PAC had a good adsorption effect on small molecular weight organic compounds, but with the increase of molecular weight of organic compounds, the adsorption effect of PAC gradually weakened, and it had no adsorption effect on macromolecular organic compounds. Based on the research of fuzzy control theory, an Agent control system for ozone oxidation process of industrial waste water based on Mobile Agent Server (MAS) theory was established, which was realized by fuzzy control method. The simulation results showed strong stability and verified the feasibility and adaptability of the distributed intelligent waste water treatment system based on MAS theory in the actual control process.

Catalytic wet peroxide oxidation degradation of magenta wastewater and preparation of FeOCl/montmorillonite.

The iron oxychloride/pillared montmorillonite (FeOCl/MMT) catalyst was prepared by wet impregnation method and solid melting method. Various characterization techniques were used to analyze the microscopic morphology and structure of a series of catalysts. Moreover, the catalysts were used to treat magenta-simulated dye wastewater through catalytic wet peroxide oxidation (CWPO) degradation. The magenta removal rate and chemical oxygen demand (COD) removal rate of the magenta-simulated dye wastewater were used to evaluate the catalytic performance of the catalyst, and the optimal catalyst preparation conditions were selected. The results showed that the solid melting method was more favorable to the preparation of the catalyst, and the COD removal rate of wastewater can reach 70.8% when the FeOCl load was 3%. Moreover, 96.2% of the magenta in the solution was removed. The COD removal rate of the magenta wastewater decreased by only 12.4% after the catalyst was repeatedly used six times, indicating that the catalyst has good activity and stability. The Fermi equation can simulate the reaction process of the catalyst treating magenta wastewater at high temperature.

Modification of polyurethane sponge filler using medical stones and application in a moving bed biofilm reactor for ex situ remediation of polluted rivers

The application of moving bed biofilm reactors is a prospective water remediation technology, but its treatment efficiency needs to be further improved. In this study, moving bed biofilm reactors were applied for ex situ remediation of polluted rivers, and medical stones were newly used for modification of polyurethane sponge filler. The porosity, water-holding capacity and apparent density of the modified filler were 8.24%, 32.74% and 5.2 times higher than non-modified filler, respectively, which is more favourable to microbial attachment and growth. The developed moving bed biofilm reactors had a good removal effect on the chemical oxygen demand, ammonia, and total nitrogen of polluted urban-river water with hydraulic retention times of 12 h, 6 h, and even 3 h. The chemical oxygen demand, ammonia, and total nitrogen removal rates of moving bed biofilm reactors containing modified filler were 88.06%, 93.67% and 67.10%, respectively, which are 4.86%, 8.89% and 9.01% higher than moving bed biofilm reactors with non-modified filler, respectively, at the shortest hydraulic retention time, 3 h. In summary, this study provides a new kind of filler for moving bed biofilm reactors in ex situ remediation of polluted urban rivers, targeting rapid removal of chemical oxygen demand, ammonia, and total nitrogen.