Treatment Of Paper Mill Effluent Research Articles

Advancing cobalt ferrite-supported activated carbon from orange peels for real pulp and paper mill wastewater treatment

The utilization of agriculture waste-based adsorbents in the treatment of real industrial wastewater represents an unexplored frontier with significant potential. In this study, the cobalt ferrite-supported activated carbon derived from orange peels (CF40-AC) was used as a magnetic adsorbent for the treatment of real pulp and paper mill effluent (PPME). Detailed insights into the properties and functionalities of the CoFe2O4-AC adsorbent were obtained through an accurate characterization analysis that included X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDX), BET and pore size histogram techniques. Both pure activated carbon (AC) and CF40-AC displayed excellent textural properties with surface area (SBET) equal 2014 and 1345 m2.g−1, respectively. TEM and SEM images display that the magnetic ferrites were well dispersed on the surface of AC. Following the characterization process, the CoFe2O4-AC adsorbent was evaluated for its ability to remove several key pollutants from PPME, including chemical oxygen demand (COD), total dissolved solids (TDS) and turbidity. Moreover, various operational parameters, such as pH, adsorbent dosage, contact time, and stirring rate, were investigated to achieve optimal contaminants removal rates. Remarkably, the CoFe2O4-AC adsorbent demonstrated highly efficient removal rates, with 86.9%, 59,9% and 93.1% for COD, TDS and turbidity, respectively, under optimal conditions (pH 7, adsorbent dose 0.4 gm, contact time 60 min, and stirring rate 150 rpm). The CoFe2O4-AC composite material exhibits promising potential for multiple applications reached 5 cycles without a significant loss in its adsorption or functional properties over successive uses. These results favor the promising potential of CoFe2O4-AC as a sustainable and efficient solution for addressing wastewater treatment challenges in the pulp and paper industry, contributing to both environmental protection and resource conservation.

Exploring the potential of bacterial consortium for the treatment of paper mill effluent treatment through various treatment strategies and evaluation of their toxicity

Paper mill effluent containing kraft lignin (KL) and other toxic compounds poses serious environmental health concerns due to its potential for bioaccumulation. A prospective bacterial consortium is still needed for the remediation of paper mill effluent. Therefore, the current work aims to explore the potential of consortium, i.e. Bacillus cereus, B. paramycoides, and B. aryabhattai via different treatment strategies: batch, continuous, multipulse, and dissolved oxygen (DO) stat fed-batch for maximum detoxification of effluent under optimised conditions. A minimal salt medium containing 1.0 % glucose, 0.5 % ammonium nitrate, and pH 8.0 was the optimum condition for the consortium to degrade 1000 mg/L of kraft lignin in the effluent. Laboratory adaptation evolution (LAE) studies showed that the maximum number of bacterial generations was observed within 178 h at 5th cycle for 3000 mg/L kraft lignin. The maximum removal of KL, color, chemical oxygen demand (COD), biological oxygen demand (BOD), and total phenol by the dissolved oxygen stat fed-batch treatment strategy was 94 %, 86 %, 91 %, 90 %, and 97 %, respectively. Phytotoxicity testing of the consortium-treated effluent on Vigna radiata L., and Trigonella foenum-graecum L. revealed a reduction in phytotoxicity by ∼66 % and ∼68 %, respectively. The genotoxicity study on Allium cepa L. showed that the percent of aberrant cells with different chromosomal aberrations was decreased in consortium-treated effluent as compared to untreated effluent. This work provides a new insight and strategy for the paper mill effluent treatment at an industrial scale. Statement of environmental implicationThe paper mill effluent contains various hazardous compounds; chlorinated phenols, dioxins, kraft lignin, and endocrine disrupting compounds, when discharge from industries without proper treatment. This effluent causes mutagenic, clastogenic, carcinogenic, and endocrine-disrupting mechanisms in flora and fauna. This study provides a comparative performance evaluation of different treatment strategies: batch, continuous fed-batch, multipulse fed-batch, and dissolved oxygen stat fed-batch, for paper mill effluent treatment using a bacterial consortium for maximum removal of kraft lignin, color, chemical oxygen demand, total phenol concentration, and quantified ligninolytic enzyme production. Treated effluent showed a lesser phytotoxic and genotoxic effect. Therefore, the results of this study are suitable for environmental restoration. Significance of studyContrastingly, throughout this study, found that bacterial consortium have superior detoxifying qualities of paper mill effluent compared to pure cultures, via different treatment strategies: batch, continuous, multipulse, and dissolved oxygen stat fed-batch strategies under optimised conditions at lab scale. According to these results, such dissolved oxygen stat fed-batch strategy mediated treated effluent that promotes seed germination and showed a higher mitotic index of root cells of the plant in contrast to untreated effluent. Therefore, these treatment strategies are adequate, effective, and sustainable to reduce the significant pollution load in effluent.

Exploring the application of the hybrid nano-bioreactor technology based on the developed polyethersulfone mixed-matrix membrane for industrial effluent treatment

Due to the high concentration of various contaminants in the paper mill effluent, it must undergo an efficient treatment process before being discharged to the environment or being reused in the production cycle. In the present study, the submerged membrane adsorption bioreactor (SMABR) system was used for the treatment of the paper mill effluent. The modified polyethersulfone PES/MoS2 membrane was fabricated by incorporating exfoliated MoS2 nanosheets prepared in the laboratory, into the PES matrix. This membrane along with the powdered activated carbon (PAC) were utilized in the SMABR system for the paper mill effluent treatment. After the acclimation of the sludge with the target effluent, the optimum values of food to microorganism (F/M), hydraulic retention time (HRT), and adsorbent dosage were determined separately to be 0.451, 18 h, and 3 g/L by considering the maximum values of chemical oxygen demand (COD) removal and mixed liquor suspended solid MLSS concentration in each stage. In the final stage, the MBR and SMABR systems (using the pristine and modified membranes, separately) were prepared to separately investigate the effect of the presence of the PAC adsorbent and modified membrane, on the output parameters. In all systems, the values of pH and dissolved oxygen (DO) were maintained in the normal range (pH: 6.2–6.7, DO>2) to provide favorable conditions for the growth of microorganisms. Most importantly, best performance in this study was related to the SMABR system consisting the PES/MoS2 membrane and PAC adsorbent, with the highest values of COD removal (96%), MLSS concentration (15620 mg/L), and membrane permeation flux (110 L/m2.h). It is worth mentioning that the functionalized membrane exhibited better hydrophilicity compared with the pristine membrane, resulting in high water permeation flux, which is in accordance with the performance results.

Anaerobic Biodegradability Potential of RCF-Based Kraft Paper Mill Effluent

The present study collected anaerobic sludge from a paper mill operating a UASB reactor on agro-based raw material (wheat straw) washings for biogas production. After determining the sludge profile and methanogenic activity of anaerobic sludge, it was further used to determine the anaerobic biodegradability of RCF-based kraft paper mill effluent. The sludge profile of collected anaerobic sludge was found w.r.t. Suspended Solids (SS) 60 g.L-1, Volatile Suspended Solids (VSS) 23 g.L-1, Inorganic content 62% & Organic content 38%. The presence of effective microbes in anaerobic sludge was confirmed by SEM (Scanning Electron Microscope). Degradation of organic matter present in effluent by anaerobic digestion leads to the production of biogas (methane & CO2), a renewable energy source. The sludge profile and methanogenic activity findings supported the anaerobic treatment of kraft paper mill effluent and were positive. The methanogenic activity of anaerobic sludge was determined as 0.832 gCOD.gVSS-1×Day, and the average anaerobic biodegradability of RCF-based kraft paper mill effluent was found to be 71.5%.

Pulp and Papermill Effluent Treatment by Continuous Electrocoagulation

The continuous electrocoagulation (CEC) technique, which uses aluminium (Al) as an electrode material, is examined in this work for the treatment of highly toxic pulp and papermill effluents. The process optimization was done with respect to the flow rates (L h−1) and residence time (τ) of wastewater which resulted in the excellent removal of Total solids (TS), colour and Chemical Oxygen Demand (COD). The removal rate of COD was 94.4 and 93.1% at the optimal flow rates of 0.5 and 1.0 dm3 h−1, correspondingly, whereas the colour removal rate was 91.6 and 83.6%. There was gradual decrease in the pH of the effluent during the process due to the production of aluminium hydroxides in variable oxidation states. Variation in the cell voltage during the electrolysis has also been studied. TDS of effluent was also decreased by a factor of 93% after 4 h residence time at a flow rate of 0.5 dm3 h−1. With a variation in flow rates, electrode degradation and consumption were also examined.

Oxidative Treatment of Paper Mill Effluent by TiO2 Photocatalysis and Photo-Fenton Reagent

The pulp and paper industry have historically been one of the world’s largest consumers of freshwater resources and producers of wastewater discharges. More than 250 chemicals have been identified in effluents including chlorine-based organic and other toxic compounds. Some of these are resistant to biological degradation such as color-related compounds. The goal of this study was to analyze the real wastewater from the paper mill and to suggest a photocatalytic treatment method in order to reduce the organic pollutants load. The efficiency of the commonly used treatment photocatalytic processes (photo-TiO2 and photo-Fenton reagent) on the treatment of real paper mill effluent was investigated. Additionally, the performance of TiO2 photocatalytic reactions with and without the addition of hydrogen peroxide was also examined. For the experiment, a 500 mL pyrex UV reactor and a 125-W high-pressure mercury lamp, surrounded by pyrex filter blocking wavelengths below 290 nm were used. The approach has been applied for the treatment of effluents produced from a papermaking industry.

Evaluation of application potential of dye-decolorizing peroxidase from Bacillus amyloliquefaciens in bioremediation of paper and pulp mill effluent.

Pulp and paper mill effluent is rich in recalcitrant and toxic pollutants compounds and causes pollution. To find an efficient biocatalyst for the treatment of effluent, a dye-decolorizing peroxidase from Bacillus amyloliquefaciens MN-13, which is capable of degrading lignin, was used for the bioremediation of paper and pulp mill effluent. The dye-decolorizing peroxidase from Bacillus amyloliquefaciens (BaDyP) exhibited high-redox potential to 2, 2'-azinobis (3-ethylbenzothiazoline- 6-sulfonic acid) ammonium salt (ABTS), veratryl alcohol, Mn2+, reactive blue 19, reactive black 5 and lignin dimer guaiacylglycerol-beta-guaiacyl ether (GGE). When GGE was used as substrate, BaDyP broke β-O-4 bond of GGE and then oxidize Cα to generate vanillin. The Km values for ABTS and veratryl alcohol were 2.19 mm and 0.07 mm, respectively. The Vmax for ABTS and veratryl alcohol were 1.8 mm/min and 14.12 mm/min, respectively. The BaDyP-mediated treatment of pulp and paper mill effluent led to significant reduction of chemical oxygen demand (COD) and color. When 5% (v/v) of effluent was treated with BaDyP for 12 h at 30°C and pH 2, the removal of COD, color, and lignin was achieved at 82.7, 80.2, and 78.20%, respectively. In detoxification assay, the seeds of Vigna unguiculata grown in treated effluent showed a significant increase in germination rate from 66.7% (untreated effluent) to 90%, and in radicle length from 0.68 cm (untreated effluent) to 1.26 cm, respectively. In the meanwhile, the inhibition of Escherichia coli and Bacillus subtilis by the treated effluent reduced significantly as compared to untreated effluent, indicating high detoxification performance of BaDyP for the treatment of pulp and paper mill effluent. The findings suggest that BaDyP is a potential catalyst for bioremediation of pulp and paper mill effluent, as it is effective in substantial lowering of pollutants load as well as reduces COD, color, and toxicity of effluent.

Characteristics and treatment of Brazilian pulp and paper mill effluents: a review.

Pulp and paper industries are very important for developing the Brazilian economy. During production processes, many effluents are generated with high polluting potential. The objective of this study is to conduct an extensive literature review on the characteristics of effluents and treatment forms adopted by Brazilian mills in this industrial sector. Most consulted studies address raw (without treatment) and secondary (after biological treatment) effluents, considering their main characteristics like pH, chemical and biochemical oxygen demands (COD and BOD, respectively), color, solids, organochlorines, toxicity, estrogenic activity, and phenols. Raw effluents differ considerably in composition, depending on the type of paper produced, the pulping process employed, and other steps, like pulp bleaching. Raw effluent characteristics indicate that this effluent cannot be directly disposed of into water bodies, because it does not comply with federal and state disposal standards. Secondary effluents normally comply with Brazilian legislations, although some studies have reported COD and total phenol concentrations higher than disposal standards, suggesting that additional treatments are necessary. Treated effluent reuse was verified in some Brazilian mills, while its disposal in eucalyptus plantations has been considered a promising alternative for irrigation purposes.

Optimization of COD Removal from Pulp and Paper Mill Effluent using Electrooxidation

Available treatment methods for pulp and paper industries waste effluent include biological treatment, adsorption, chemical precipitation, which are of high cost of the treatment and suitable for small and medium scale industries. Among the available methods, the chemical precipitation method is commonly used, which requires addition of chemical coagulants and generates more sludge compared to electrooxidation. The electrochemical method of organic matter destruction is a suitable alternative for the treatment of pulp and paper mill effluent, which combines the benefit of electrooxidation and electrocoagulation, capable of removing fine particles as a result of coagulation and electric field. The objective of the study is to evaluate the potential of electrooxidation for organic matter destruction from the pulp and paper mill effluent under various operating conditions such as pH, voltage, reaction time, and to optimize the operating conditions to maximize COD removal using response surface modelling. The wastewater for this study was collected from a pulp and paper mill located in Odisha, with wastewater collected from the outlet of the wastewater discharge before entering the treatment plant, and stored under 20 C to prevent its degradation. The results obtained from this study concluded 73.48% COD removal under optimum conditions (pH=9, V=11.2 V, RT=60 min) however, under experimental conditions, COD removal of 72.90% was observed. This batch monopolar electrooxidation system is efficient to remove COD from pulp and paper mill wastewater, and further studies are required on a continuous reactor to scale up the COD removal by electrooxidation. Keywords: Biological Treatment, Electrooxidation, Electrocoagulation, Chemical Precipitation, Sludge

Comparative Study and Possible Phycoremediation of Effluent of JK Pulp and Paper Mill and Select Heavy Metals on Cyanobacteria

Pulp and Paper Mill effluent contains toxic heavy metals like Hg, Cd and Pb. These effluent are deadly toxic to the aquatic organisms as these effluents are discharged into River Nagavalli without biological treatment. The main objective of the present study was to assess the Paper mill effluent: its impact on blue green algae (BGA) and whether BGA can be used for detoxification of the effluent waste water. The contaminated river water contained significant amount of heavy metals. An attempt was made to study the impact of heavy metals like Hg, Cd and Pb present in effluent on BGA/cyanobacterium under laboratory controlled conditions and a strategy was planned to study these heavy metals in combination as mixture. All the heavy metals tested showed stimulation and better growth at sub-lethal concentrations (MAC value) but at higher concentrations heavy metals were deadly toxic. The heavy metals when combined produced higher toxicity. No stimulation in the exposed alga was observed in heavy metal combinations. The algae could remove heavy metals from the effluent of the paper mill. The paper mill effluent though highly toxic but showed better behavior at sub-lethal concentrations towards the cyanobacterium. From the observed data it is evident that Westiellopsis was more tolerant than other BGA tested. This alga has potency to grow under stressful conditions and can be safely used for phycoremediation of paper mill effluent after dilution of the effluent. Along with the tested BGA other aquatic macrophytes in combination can be tried for total biological treatment of paper mill effluent before being discharged into the environment.

Biosynthesis of Zinc Oxide Nanoparticles Using Leaf Extract of Prosopis juliflora as Potential Photocatalyst for the Treatment of Paper Mill Effluent

This paper reports on the manufacture of ZnO nanoparticles (ZnO NPs) from Prosopis juliflora leaf extracts. Various methods of characterization were used, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), and transmission electron microscope TEM. ZnO NPs has a hexagonal wurtzite structure with a preferred orientation of 101 planes, according to XRD. The functional groups found in ZnO NPs isolated from leaves are responsible for the FT-IR peaks that correspond to them. The morphology of the produced nanoparticles is a sphere-like form, as shown in the SEM pictures. TEM examination revealed ZnO NPs with a size of 50–55 nm. These ZnO NPs were used to remediate pollutants in paper mill effluents, and they were able to remove 86% of the organic pollutants from the sample at 0.05 mg/L dose and reduce 89% of the organic pollutants during a 5-h reflex time. Meanwhile, for the photocatalysis of paper mill effluents, it has been noted that COD was removed by 74.30%, 63.23%, and 57.96% for the first, second, and third cycles, respectively.

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.

Valorization of pulp and paper industry wastewater using sludge enriched with nitrogen-fixing bacteria.

Nitrogen-fixing bacteria (NFB) can reduce nitrogen at ambient pressure and temperature. In this study, we treated effluent from a paper mill in sequencing batch reactors (SBRs) and monitored the abundance and activity of NFB with a view to producing a sludge that could work as a biofertilizer. Four reactors were inoculated with activated sludge enriched with NFB and fed with a high C/N waste (100:0.5) from a paper mill. Though the reactors were able to reduce the organic load of the wastewater by up to 89%, they did not have any nitrogen-fixing activity and showed a decrease in the putative number of NFB (quantified with qPCR). The most abundant species in the reactors treating high C/N paper mill wastewater was identified by Illumina MiSeq 16S rRNA gene amplicon sequencing as Methyloversatilis sp. (relative abundance of 4.4%). Nitrogen fixation was observed when the C/N ratio was increased by adding sucrose. We suspect that real-world biological nitrogen fixation (BNF) will only occur where there is a C/N ratio ≤100:0.07. Consequently, operators should actively avoid adding or allowing nitrogen in the waste streams if they wish to valorize their sludge and reduce running costs. PRACTITIONER POINTS: Efficient biological wastewater treatment of low nitrogen paper mill effluent was achieved without nutrient supplementation. The sludge was still capable of fixing nitrogen although this process was not observed in the wastewater treatment system. This high C/N wastewater treatment technology could be used with effluents from cassava flour, olive oil, wine and dairy industries.

Treatment of paper mill effluent via electrochemical reaction and assessment of antibacterial activity of ZnO nanoparticles in in-vitro conditions

A simple electrochemical approach has been strategically developed for in situ generations of ZnO nanoparticles using Zn rods as electrodes and hydrogen peroxide as the oxidant without the formation of any by-product. These ZnO nanoparticles were extended for remediation of pollutants present in paper mill effluents, and separation efficiency was found to be above 90% for hydrocarbons, 92% for lignin, 99% for phenol, and 93% of chemical oxygen demand (COD), as confirmed by gas chromatography-mass spectrometry and COD analysis. It was also observed that the experimental setup could successfully remove 99% of the color from the sample. These ZnO nanoparticles have been proven in the past to be antibacterial and were explored for its ability to inhibit the growth of both Gram-positive and Gram-negative bacteria in the effluent samples after the removal of toxic pollutants. Therefore, we proposed an electrochemical reaction for the in situ synthesis of ZnO nanoparticles for remediation of paper mill effluent as well as inhibit the bacterial growth in the treated effluent sample.

A case study on pulp and paper industry effluent treatment

Industrial effluent Management is one of the major environmental concerns, especially in developing countries under rapid industrialization. The grossly polluting industries recognized by Central Pollution Control Board (CPCB), such as Pulp and Paper Industries, poses even bigger environmental threats, owing to quantity and quality of effluent generated. This paper aimed at analyzing effluent management practices in pulp and paper industries in India, and asses the performance variability of a paper mill effluent treatment plant (ETP), as a Case Study. Majority of pulp and paper industries found to still employ conventional methods of effluent treatment. Although, most of the parameters of treated effluent are commonly reported within CPCB’s permissible discharge limits, the treatment is usually cost and energy intensive, and produce high amount of solid residuals as sludge. For the case study paper mill ETP, the treatment efficiencies of the ETP units were analyzed under variable inlet pH, TSS, TDS, BOD and COD loads. The pH variations in the range of 6.5 to 9 had little effect of COD or TSS removal, however removal efficiencies were higher for larger inlet COD or TSS loads. The results of the study could be helpful in optimizing operation of the existing ETPs, as well as, guiding on upgrading ETPs with more cost-effective and efficient units.

An experimental investigation on phytoremediation performance of water lettuce (Pistia stratiotes L.) for pollutants removal from paper mill effluent.

The present study describes the phytoremediation performance of water lettuce (Pistia stratiotes L.) for physicochemical pollutants elimination from paper mill effluent (PME). For this, pot (glass aquarium) experiments were conducted using 0% (BWW: borewell water), 25%, 50%, 75%, and 100% treatments of PME under natural day/light regime. Results of the experiments showed that the highest removal of pH (10.75%), electrical conductivity (EC: 63.82%), total dissolved solids (TDS: 71.20%) biological oxygen demand (BOD: 85.03%), chemical oxygen demand (COD: 80.46%), total Kjeldahl's nitrogen (TKN: 93.03%), phosphorus (P: 85.56%), sodium (Na: 91.89%), potassium (K: 84.04%), calcium (Ca: 84.75%), and magnesium (Mg: 83.62%), most probable number (MPN: 77.63%), and standard plate count (SPC: 74.43%) was noted in 75% treatment of PME after treatment by P.stratiotes. PCA showed the best vector length for TKN, Na, and Ca. The maximum plant growth parameters including, total fresh biomass (81.30±0.28g), chlorophyll content (3.67±0.05mgg-1 f.wt), and relative growth rate (0.0051gg-1 d-1 ) was also measured in 75% PME treatment after phytoremediation experiments. The findings of this study make useful insight into the biological management of PME through plant-based pollutant eradication while leftover biomass may be used as a feedstock for low-cost bioenergy production. PRACTITIONER POINTS: Biological treatment of paper mill effluent using water lettuce is presented. Best reduction of physicochemical and microbiological pollutants was attained in 75% treatment. Maximum production of chlorophyll, plant biomass, and highest growth rate was also observed in 75% treatment.

Adsorptive decontamination of paper mill effluent by nano fly ash: response surface methodology, adsorption isotherm and reusability studies.

In the present study, adsorption of colour and other pollutants from agro-based paper mill effluent onto fabricated coal fly ash nanoparticles (CFA-N) have been investigated. Response surface methodology was applied to evaluate the operational conditions for maximum ouster of colour from effluent by nano structured CFA-N. Maximum reduction in colour (92.45%) and other pollutants were obtained at optimum conditions: 60 min interaction time, 60 g/L adsorbent dosage and 80 rpm agitation rate. The regression coefficient values (adjusted R2 = 0.7169; predicted R2 = 0.7539) established harmony between predicted and the experimental data. The adsorption equilibrium results matched perfectly with both Langmuir and Freundlich isotherms with maximum adsorption capacity of 250 platinum-cobalt/g. Additionally, the efficacy of CFA-N was also assessed in a continuous column mode. Furthermore, the feasibility of treated effluent for irrigation purpose was checked by growing the plant Solanum lycopersicum. Overall, the findings demonstrated the outstanding role of inexpensive and abundantly available CFA-N in treatment of paper mill effluent to the required compliance levels.

Continuous treatment of paper mill effluent by electrocoagulation for holding time analysis

This paper presents the potential of continuous electrocoagulation operation for the treatment of paper mill effluent. The electrocoagulation experiments were carried out based on the batch study for holding time analysis. Process performance was assessed in terms of chemical oxygen demand, color, total dissolved solids, and total organic carbon. Continuous electrocoagulation experiments were performed at constant pH 7.45, conductivity 7.72 mS/cm2, electrode distance 1.5 cm and current density 10.35 mA/cm2 with flow rate varied between 0.1 to 0.6 L/min. Flow rate 0.2 L/min with 120 min of holding time was an optimum condition in which removal efficiencies were 82.5%, 90%, 92.5%, and 84 % for COD, Color, TDS, and TOC, respectively.

Integration of coagulation-flocculation and heterogeneous photocatalysis for the treatment of pulp and paper mill effluent

ABSTRACT A two-step process involving coagulation-flocculation followed by solar photocatalysis – based Advanced Oxidation Process (AOP) using TiO2-Reduced Graphene Oxide (TRGO) nanocomposite as catalyst has been employed for the treatment of pulp and paper mill effluent. As the effluent is loaded with a high amount of organics with initial chemical oxygen demand (COD) as high as 3516, a pre-treatment is required before applying photocatalytic treatment. Coagulation-flocculation was identified as an effective pre-treatment strategy. Among the various coagulants tested, CuSO4.5H2O showed the best % COD reduction of 84 at pH 6, at a loading of 5 g/L. The primary treatment of coagulation improved the biodegradability index from 0.23 to 0.37. TRGO photocatalyst, employed in the second stage of photocatalytic treatment was synthesised by an ultrasound assisted solvothermal method and well characterised by various spectroscopic/analytical tools. The composite was found to be an efficient solar photocatalyst and achieved 1.76 and 2.1 times more COD reduction than synthesised TiO2 and commercial P25 respectively. The final effluent after the combined treatment was neutral and the biochemical oxygen demand (BOD) and COD were 11.7 and 120 mg/L respectively which were below the given limit of National Environmental Quality Standards.

Modeling of modified anaerobic baffled reactor for recycled paper mill effluent treatment using response surface methodology and artificial neural network

ABSTRACT An improved lab-scale anaerobic baffled reactor was developed to treat recycled paper mill effluent (RPME). In this study, analysis of modified anaerobic baffled reactor (MABR) performance in RPME treatment was investigated in terms of COD removal, lignin removal and CH4 production with respect to feeding COD and hydraulic retention time. The modeling analysis was carried out using response surface methodology (RSM) and artificial neural network (ANN). By optimizing the RSM model, the optimal condition was determined at 3 days and 3.40 × 103 mg/L with predicted values for COD removal, lignin removal, and CH4 production were found to be 97.6%, 65.8%, and 4.32 L CH4/gCOD removed, respectively. This result was further validated with ANN model, which presented satisfactory MABR performance.