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The objective of this study was to assess, through simulation, conductivity variations in pulp and paper circuits when recycling waste water treatment plant (WWTP) effluent with a view to reducing fresh water use in a tissue mill. WWTP effluent was recycled in the process for different uses. A PS2000 digital model coupled with the PHREEQC chemical simulation engine was used to identify and quantify the main sources of conductivity: caustic soda, sodium bisulphite and acetate production through anaerobic microbial activity. Recycling WWTP effluent enables fresh water uptake to be reduced by 50% when used for pulp dilution or white water, by 81% when used in paper machine showers, and up to 96% for all uses combined. As fresh water use decreases, circuit closure increases along with, consequently, COD and conductivity. COD build-up can be controlled by best available techniques application. Recycling WWTP effluent has a strong impact on conductivity. However, the impact of high conductivity levels on additives performance is limited in the case of the mill studied. Acetate concentration could be controlled by better agitation of tanks or the introduction of air by pumps. Furthermore, limiting acetate production can reduce the need for caustic soda to control the pH., Competing Interests: The authors declare there is no conflict., (© 2024 The Authors This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits copying, adaptation and redistribution, provided the original work is properly cited (http://creativecommons.org/licenses/by/4.0/).)

The objective of this study was to assess, through simulation, conductivity variations in pulp and paper circuits when recycling waste water treatment plant (WWTP) effluent with a view to reducing fresh water use in a tissue mill. WWTP effluent was recycled in the process for different uses. A PS2000 digital model coupled with the PHREEQC chemical simulation engine was used to identify and quantify the main sources of conductivity: caustic soda, sodium bisulphite and acetate production through anaerobic microbial activity. Recycling WWTP effluent enables fresh water uptake to be reduced by 50% when used for pulp dilution or white water, by 81% when used in paper machine showers, and up to 96% for all uses combined. As fresh water use decreases, circuit closure increases along with, consequently, COD and conductivity. COD build-up can be controlled by best available techniques application. Recycling WWTP effluent has a strong impact on conductivity. However, the impact of high conductivity levels on additives performance is limited in the case of the mill studied. Acetate concentration could be controlled by better agitation of tanks or the introduction of air by pumps. Furthermore, limiting acetate production can reduce the need for caustic soda to control the pH. HIGHLIGHTS Modelling conductivity in pulp and paper mills.; Reuse in pulp and paper mills.; Reduction of fresh water consumption.; Anticipating discharge quality.; Reduction of chemicals uses.;

The iron concentration in natural water of acid sulfate soils is usually determined by complicated methods of SMEWW 3111B:2017 or ISO 6332: 1988 E in the laboratory for acidified water samples at pH ∼2–3. Therefore, the rapid field determination of iron content in natural water is a very useful method because it limits the error and reduces the experimental time for analysis. In this study, we proposed, developed, and tested a rapid colorimetric analysis method based on the chemical reaction of ferric and anion thiocyanate (SCN−) ions for an iron concentration range of 0–100 mg/L with a linear equation of ΔE = 0.5955x + 2.0909 and high correlation coefficient (R2) of 0.9864. The results from 10 water samples by this method were very close to those by flame absorption spectroscopy with a difference of less than 5%. Besides the biggest advantage of rapid site testing, this method also gives quite high accuracy compared to the molecular absorption method of ISO 6332:1988 E. In addition, this new method can quantify Fe3+, Fe2+, and total iron in water, suggesting a very useful and potential method for determining the iron content of natural water from acid sulfate soils. HIGHLIGHTS A color chart was developed to determine iron in water using indicator paper.; A linearity of the iron content was obtained with a concentration below 100 mg/L.; The method gives relatively fast and accurate results of Fe2+, Fe3+, and total iron.; The tested results show high accuracy and sensitivity in natural iron alum water.;

Pulp and paper wastewater (PPWW) contains numerous refractory and harmful contaminants that require advanced treatment to meet the discharge criteria. This study compared the efficacy of two PPWW treatments: ultraviolet/peroxymonosulfate (UV/PMS) and ultraviolet/H2O2 (UV/H2O2) working under similar circumstances. The initial pH value, oxidant dosage, UV radiation intensity, and pseudo-first-order constant kobs were systematically studied in both systems. Optimally, the UV/PMS process produced an effluent of higher quality than the UV/H2O2, as measured by the removal efficiencies of chemical oxygen demand (COD) in 60 min, which were 48.2 and 64.3% for the respective UV/H2O2 and UV/PMS processes and corresponding kobs values of 0.0102 and 0.0159 min−1, respectively. Radical scavenging experiments demonstrated that •OH was the primary reactive oxygen species in UV/H2O2 process, and •OH and SO4−• in the UV/PMS process. Moreover, ultraviolet-visible spectroscopy and gas chromatography coupled mass spectroscopy analyses showed that deep treatment of petroleum hydrocarbons with carbon chain lengths greater than 18 and macromolecular semi-volatile organic compounds in paper wastewater is difficult, whereas the UV/PMS process can significantly improve the removal of amides, esters, phenols, and other aromatic compounds. HIGHLIGHTS UV/PMS is a worthwhile in-depth study to achieve more effective treatment of actual wastewater.; It was difficult to completely degrade the organics in actual PPWW due to some long-chain alkanes and macromolecules containing benzene ring organic substances.;

Although in a critical position in the economy, the paper industry releases a lot of wastewater that requires adequate treatment for sustainable development. This study presents an application of Life cycle assessment (LCA) with the ReCiPe tool on the wastewater treatment plant (WWTP) of a paper factory in Vietnam to evaluate the environmental effect of the individual techniques in WWTP, especially the internal circulation (IC) reactor, a pioneer and practical anaerobic technology. Both Midpoint and Endpoint categories results demonstrated that chemical use and electricity consumption mainly contributed to the environmental impact in the WWTP. The Dissolved air flotation (DAF) and Moving bed biofilm reactor (MBBR) are classified as effective techniques to reduce the impacts on the environment. Moreover, the comparison of LCA between IC and up-flow anaerobic sludge bed (UASB) shows that IC is the better practically green technique for the environment. HIGHLIGHTS Life cycle assessment was applied in a paper mill wastewater treatment plant.; Midpoint and Endpoint indicators were employed to evaluate environmental impact.; Two scenarios of electricity generating from biogas between Internal circulation and up-flow anaerobic sludge bed were investigated.; Chemicals use and energy consumption were determined to be the most factors to damage indicators.;

This study carried out the anaerobic digestion of recycled paper mill wastewater (RPMW) in a high-rate novel anaerobic baffled reactor. The parametric interaction between influent chemical oxygen demand (CODin) and hydraulic retention time (HRT) was modeled, and process responses were optimized by the response surface methodology (RSM) using a three-level factorial design. The results showed that the optimal condition was determined at CODin of 4,000 mg/L and HRT of 2 days and predicted values for COD removal, biochemical oxygen demand (BOD) removal, lignin removal, CH4 content, and CH4 production were found to be 94%, 98%, 68%, 85%, and 20.8 L CH4/d, respectively. According to the statistical analysis of the RSM, all models were significant with very low probability values (from 0.0045 to

Hydrothermal liquefaction derived hydrochar produced from industrial paper sludge was used as an adsorbent to remove phenol derivatives from an industrial wastewater stream. Removal efficiency for phenol was determined using synthetic solutions (10–150 ppm) using batch adsorption experiments at a constant solution pH (8), temperature (25 ± 2 °C) and rotary speed (150 rpm). The adsorption of phenol onto hydrochar followed a Freundlich isotherm and could be described with pseudo-second-order kinetic models. Analysis of the adsorption mechanisms showed that particle film mass transport was the rate-determining step in the adsorption process. A COD removal efficiency of 31 ± 1% was achieved for the industrial wastewater stream. All phenol components in the wastewater stream could be removed, but not all organic acids and cyclic ketones. The performance of the paper sludge-based hydrochar compared well with that of activated carbon (44% COD removal). The final phenol concentration in the wastewater stream was below the acceptable phenol concentration for industrial effluents (1 mg/L). The results show that paper sludge can be converted to a valuable marketable commodity that could reduce waste management costs for a paper mill, while also reducing the cost of expensive adsorbents. Highlights Industrial paper sludge waste was successfully converted to effective bio-adsorbent.; HTL-based biochar was used as adsorbent without any pretreatment.; 77.83% COD removal from industrial wastewater could be obtained.; Final total phenol concentration was below 1 ppm.; Bulk fluid mass transfer was the rate determining step in the adsorption process.;

Anaerobic digestion (AD) is an essential technology for wastewater management, resource recovery and biogas production, and it is considered as an efficient and reliable treatment method for many wastewaters. Operating parameters have been shown to directly affect the stability and treatment performance of AD, especially temperature. For 180 days, the AD of recycled paper mill wastewater (RPMW) was carried out in a modified anaerobic inclining-baffled (MAIB) reactor under various temperature conditions, i.e. 29 °C (low mesophilic), 37 °C (mesophilic) and 55 °C (thermophilic). It was found that total COD removal of 94, 96 and 76%, and methane yields of 0.125, 0.196 and 0.256 L CH4/g CODremoved were attained at temperatures of 29, 37 and 55 °C, respectively. Throughout the three transition periods, the pH level in the MAIB reactor fluctuated slightly within the range of 5.8–6.5 without affecting the system stability. The results concluded that thermophilic condition strongly influenced the MAIB reactor performance, leading to lower COD removal, higher methane yield and gradually recovered pH level. Highlights Novel modified anaerobic inclining-baffled (MAIB) reactor, which combines the development of attached and settled microorganisms, was operated for the treatment of recycled paper mill wastewater (RPMW).; The operational temperature intensive analysis of MAIB was investigated at thermophilic and mesophilic conditions.; The system compartmental characteristics were also analyzed and discussed.;

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. HIGHLIGHTS Nano fly ash was successfully utilized for removal of colour and other pollutants from agro-based paper mill effluent.; RSM using BBD was used to optimize the operational conditions.; Quadratic models have been established for the response variables.; Fixed-bed column adsorption studies illustrated the feasibility of nano fly ash for pilot-scale applications.; The reusability of treated effluent for irrigation was examined.;

In recent years, the use of microalgae as feedstock for many marketable products, such as animal/aqua feeds, bioplastics and fertilizers, has gained renewed interest due to their fast growth potential coupled with relatively high lipid, carbohydrate and nutrient content. An algal biorefinery at an industrial site has the potential to sustainably and profitably convert carbon dioxide emissions into microalgal biomass and concomitantly reduce nitrogen and phosphorus from wastewaters. Industrial wastewaters are a potential alternative to traditional media used for large-scale microalgal cultivation. Pulp and paper mills are major consumers of water resources and discharge a huge amount of water to nearby lakes or rivers. This study investigated whether pulp and paper mill waste water is suitable for microalgal cultivation with the aim of achieving significant biomass production. Six different process waters from one Canadian pulp and paper mill were tested with two freshwater green microalgae. All of these waters were unable to support growth of microalgae due to inadequate nutrient concentrations, colour, turbidity and possible toxicity issues. HIGHLIGHTS Two freshwater microalgae strains were screened for potential growth on pulp and paper effluents.; Pulp and paper wastewater effluents were unable to support growth of the microalgae.; Chemical residues from the pulping process, such as peroxide and tannin, may inhibit algal growth.;

Lignin is a major by-product of pulp and paper industries, and is resistant to depolymerization due to its heterogeneous structure. Degradation of lignin can be achieved by the use of potential lignin-degrading bacteria. The current study was designed to evaluate the degradation efficiency of newly isolated Bacillus altitudinis SL7 from pulp and paper mill effluent. The degradation efficiency of B. altitudinis SL7 was determined by color reduction, lignin content, and ligninolytic activity from degradation medium supplemented with alkali lignin (3 g/L). B. altitudinis SL7 reduced color and lignin content by 26 and 44%, respectively, on the 5th day of incubation, as evident from the maximum laccase activity. Optimum degradation was observed at 40 °C and pH 8.0. FT-IR spectroscopy and GC-MS analysis confirmed lignin degradation by emergence of the new peaks and identification of low-molecular-weight compounds in treated samples. The identified compounds such as vanillin, 2-methyoxyhenol, 3-methyl phenol, oxalic acid and ferulic acid suggested the degradation of coniferyl and sinapyl groups of lignin. Degradation efficiency of B. altitudinis SL7 towards high lignin concentration under alkaline pH indicated the potential application of this isolate in biological treatment of the lignin-containing effluents. HIGHLIGHTS Bacillus altitudinis SL7 isolated from effluent could efficiently degrade lignin under alkaline conditions.; Degradation efficiency was determined by analyzing lignin content, color reduction, and ligninolytic enzyme activity.; Extracellular laccase from B. altitudinis SL7 can play a significant role in the depolymerization of lignin.; Various low-molecular-weight lignin degradation products were determined through GC-MS.;

Lignin is a major by-product of pulp and paper industries, and is resistant to depolymerization due to its heterogeneous structure. Degradation of lignin can be achieved by the use of potential lignin-degrading bacteria. The current study was designed to evaluate the degradation efficiency of newly isolated Bacillus altitudinis SL7 from pulp and paper mill effluent. The degradation efficiency of B. altitudinis SL7 was determined by color reduction, lignin content, and ligninolytic activity from degradation medium supplemented with alkali lignin (3 g/L). B. altitudinis SL7 reduced color and lignin content by 26 and 44%, respectively, on the 5th day of incubation, as evident from the maximum laccase activity. Optimum degradation was observed at 40 °C and pH 8.0. FT-IR spectroscopy and GC-MS analysis confirmed lignin degradation by emergence of the new peaks and identification of low-molecular-weight compounds in treated samples. The identified compounds such as vanillin, 2-methyoxyhenol, 3-methyl phenol, oxalic acid and ferulic acid suggested the degradation of coniferyl and sinapyl groups of lignin. Degradation efficiency of B. altitudinis SL7 towards high lignin concentration under alkaline pH indicated the potential application of this isolate in biological treatment of the lignin-containing effluents.

This review paper on groundwater protection measures in South Africa focuses on the actual implementation of groundwater protection measures, in particular, the resource-directed measures (RDM) as described in Chapter 3 of the National Water Act (NWA). Significant catchment-wide implementation of RDM has taken place in a phased manner throughout various catchments since 2012. By 2015, approximately R380 million had been expended on the catchment-wide implementation of the water resource protection measures over a period of 15 years. Considerable effort went into refining the RDM methodology, taking into account the groundwater component of the overall resource. In this paper, we contend that RDM, in its present form, will not make a significant contribution to groundwater resource protection and security in the country. This is a major concern because the Groundwater Strategy of the Department of Human Settlements, Water and Sanitation (DHSWS) had declared the protection of groundwater as a national priority. This paper also examines institutional and governance arrangements (or lack thereof) as well as providing recommendations to support the effective implementation of groundwater protection provisions as prescribed by South Africa's water legislation. HIGHLIGHTS Groundwater protection measures and its significant catchment-wide implementation to date.; Resource-directed measures methodology.; Groundwater Reserve determination.; Water resource classification and resource quality objectives.; Implementation of water resource legislative and scientific measures.;

The paper mill industry produces high amounts of wastewater and, for this reason, stringent discharge limits are applied for sustainable reclamation and reuse of paper mill industry wastewater in many countries. Submerged membrane bioreactor (sMBR) systems can create new opportunities to eliminate dissolved substances present in paper mill wastewater including. In this study, a sMBR was operated for the treatment of paper mill industry wastewater at 35 h of hydraulic retention time (HRT) and 40 d of sludge retention time (SRT). The chemical oxygen demand (COD), NH 3 -N and total phosphorus (TP) removal efficiencies were found to be 98%, 92.99% and 96.36%. The results demonstrated that sMBR was a suitable treatment for the removal of organic matter and nutrients for treating paper mill wastewater except for the problem of calcium accumulation. During the experimental studies, it was noted that the inorganic fraction of the sludge increased as a result of calcium accumulation in the reactor and increased membrane fouling was observed on the membrane surface due to the calcification problem encountered. The properties of the sludge, such as extracellular polymeric substances (EPS) and soluble microbial products (SMP), relative hydrophobicity, zeta potential and floc size distribution were also monitored. According to the obtained results, the total EPS was found to be 43.93 mg/gMLSS and the average total SMP rejection by the membrane was determined as 66.2%.

The objective of this study was to evaluate the closing of the water circuit and reusing the treated effluent in the production of TMP, using simulations performed with the Aspen Plus ® . The treated effluent was reused to replace 50, 75 and 100% of the well water. An adaptation of the Aspen Plus ® program simulating the TMP production process and a dynamic simulation test to verify the accumulation of non-process elements (NPEs) in industrial processes at different proportions of reuse were evaluated. The quality of the final product was assessed in laboratory bleaching tests for pulp brightness and brightness reversion. The concentrations of the NPE were 0.00097, 0.00122 and 0.00145 kmol/h for Mn 2+ , 0.012929, 0.018368 and 0.023595 kmol/h for Fe 2+ and 0.000542, 0.000722 and 0.000948 kmol/h for Cu 2+ , with the recycling of the treated effluent of 50, 75 and 100%, respectively. The brightness and brightness reversion of the pulp were similar with the different proportions of effluent reuse and with the use of fresh industrial water, with values ranging from 83.37 to 83.97% ISO and 5.43 to 6.38 ISO units, respectively. The use of treated effluent did not affect the pulp quality, which could diminish the water use a pulp mil.

Industrial wastewaters and their treatment are now placed at the heart of the environmental concerns that industries face. Some research work has been carried out in order to limit the impact of these wastes on the environment as well as their costs. In this study, wastewater dehydrated sludge (55% wt. water content) from the paper industry was used to recover cellulose by using tetrakis(hydroxymethyl)phosphonium chloride, [P(CH2OH)4]Cl, ionic liquid as a solvent. The ionic liquid has shown remarkable results in terms of cellulose extraction in addition to its non-volatility and lower toxicity compared to organic volatile solvents. All cellulose, based on dry sludge, was recovered from the industrial dehydrated sludge with better operation conditions. The influence of temperature and the quantity of ionic liquid was preliminary studied in order to optimise the extraction conditions. [ABSTRACT FROM AUTHOR]

A filter paper was functionalized with β-cyclodextrin and citric acid via esterification reaction for the removal of dyes and Cu ions from aqueous solutions. The adsorption capacity and removal performance of the modified filter paper (MFP) was investigated using static and dynamic adsorption experiments. The static adsorption data fit well the Langmuir and pseudo-second-order models, and the adsorption capacity of Methylene Blue (MB), Brilliant Green (BG), Rhodamine-B (RB) and Cu(II) over the MFP were 124.6 mg/g, 130.4 mg/g, 99.7 mg/g and 39.1 mg/g, respectively, which are much higher than the unmodified filter paper (below 2 mg/g). Even better, the decolorization performance and Cu(II) removal of MFP are remarkable in dynamic adsorption. The effluent can reach the National Standard for dyeing and finishing of textile industry of China after three cycles in a continuous filtration-adsorption system. This method provides a new pathway to achieve high efficiency removal of dyes and metal ions from wastewater. [ABSTRACT FROM AUTHOR]

The potential growth of buffalo grass (Stenotaphrum secundatum) and couch grass (Cynodon dactylon) on artificial floating islands (AFIs) and their ability to remove total nitrogen (TN) and total phosphorus (TP) from a simulated paper mill wastewater was studied. This was done to assess the potential of AFIs for removal of nutrients from aerated stabilization basins (ASBs) that had occasional growth of blue-green algae (BGA) to bloom levels. Small scale AFIs were prepared using polyethylene foam and planted with the grasses in 30 L of tested water. Trials were conducted in a plastic covered greenhouse over a three-month period where temperatures ranged from 15 to 44 °C. The results showed that both buffalo and couch grasses can adapt to planting in AFIs showing increases of 125% and 148% in wet weight, respectively. Nutrient uptake by buffalo grass and couch grass were found to be similar. Percentage uptakes of TP and TN from the synthetic water by the buffalo grass were 82% and 47%, whereas by couch grass, uptakes were 83% and 45%, respectively. [ABSTRACT FROM AUTHOR]

The activated sludge process is an old technology, but still the most commonly used one for treatment of wastewater. Despite the wide spread usage the technology still suffers from instability (Tandoi et al. 2006) and high operating cost. Activated sludge processes often carry a large solids inventory. Managing the total inventory without interference is the key component of the optimization process described in this paper. Use of nutrients is common in pulp and paper effluent treatment. Feeding enough nutrients to support the biomass growth is a delicate balance. Overfeeding or underfeeding of nutrients can result in higher costs. Detrimental substances and toxic components in effluents entering a biological treatment system can cause severe, long lasting disturbances (Hynninen & Ingman 1998; Bergeron & Pelletier 2004). A LumiKem test kit is used to measure biological activity with adenosine triphosphate (ATP) in a pulp and paper mill. ATP data are integrated with other standardized mill parameters. Measurements of active volatile suspended solids based on ATP can be used to quantify the living biomass in the activated sludge process and to ensure that sufficient biomass is present in order to degrade the wastewater constituents entering the process. Information about active biomass will assist in optimizing sludge inventories and feeding of nutrients allowing the living biomass to re-populate to create optimal efficiency. ATP measurements can also be used to alert operators if any components toxic to bacteria are present in wastewater. The bio stress index represents the stress level experienced by the microbiological population. This parameter is very useful in monitoring toxicity in and around bioreactors. Results from the wastewater process optimization and ATP measurements showed that treatment cost could be reduced by approximately 20-30% with fewer disturbances and sustained biological activity compared to the reference period. This was mainly achieved by the removal of detrimental substances and optimized nutrient dosage.

This study deals with chemical oxygen demand (COD), phenol and Ca+2 removal from paper mill industry wastewater by electrocoagulation (EC) and electro-Fenton (EF) processes. A response surface methodology (RSM) approach was employed to evaluate the effects and interactions of the process variables and to optimize the performance of both processes. Significant quadratic polynomial models were obtained (R² = 0.959, R² = 0.993 and R² = 0.969 for COD, phenol and Ca+2 removal, respectively, for EC and R² = 0.936, R² = 0.934 and R² = 0.890 for COD, phenol and Ca+2 removal, respectively). Numerical optimization based on desirability function was employed; in a 27.55 min trial, 34.7% of COD removal was achieved at pH 9 and current density 96 mA/cm² for EC, whereas in a 30 min trial, 74.31% of COD removal was achieved at pH 2 and current density 96 mA/cm² and H2O2/COD molar ratio 2.0 for EF. The operating costs were calculated to be 6.44 €/m³ for EC and 7.02 €/m³ for EF depending on energy and electrode consumption at optimum conditions. The results indicate that the RSM is suitable for the design and optimization of both of the processes. However, EF process was a more effective technology for paper mill industry wastewater treatment as compared with EC. [ABSTRACT FROM AUTHOR]

Pulp and paper wastewater (PPWW) contains numerous refractory and harmful contaminants that require advanced treatment to meet the discharge criteria. This study compared the efficacy of two PPWW treatments: ultraviolet/peroxymonosulfate (UV/PMS) and ultraviolet/H 2 O 2 (UV/H 2 O 2 ) working under similar circumstances. The initial pH value, oxidant dosage, UV radiation intensity, and pseudo-first-order constant k obs were systematically studied in both systems. Optimally, the UV/PMS process produced an effluent of higher quality than the UV/H 2 O 2 , as measured by the removal efficiencies of chemical oxygen demand (COD) in 60 min, which were 48.2 and 64.3% for the respective UV/H 2 O 2 and UV/PMS processes and corresponding k obs values of 0.0102 and 0.0159 min -1 , respectively. Radical scavenging experiments demonstrated that •OH was the primary reactive oxygen species in UV/H 2 O 2 process, and •OH and SO 4 • in the UV/PMS process. Moreover, ultraviolet-visible spectroscopy and gas chromatography coupled mass spectroscopy analyses showed that deep treatment of petroleum hydrocarbons with carbon chain lengths greater than 18 and macromolecular semi-volatile organic compounds in paper wastewater is difficult, whereas the UV/PMS process can significantly improve the removal of amides, esters, phenols, and other aromatic compounds.- • in the UV/PMS process. Moreover, ultraviolet-visible spectroscopy and gas chromatography coupled mass spectroscopy analyses showed that deep treatment of petroleum hydrocarbons with carbon chain lengths greater than 18 and macromolecular semi-volatile organic compounds in paper wastewater is difficult, whereas the UV/PMS process can significantly improve the removal of amides, esters, phenols, and other aromatic compounds.

The porous metallic iron/carbon (Fe 0 /C) ceramsites, with virtues of low cost and 'green' fabrication, were prepared by direct reduction roasting of magnetite, coal, and paper mill sludge. The X-ray diffraction data revealed that Fe 0 was generated in situ by reducing the magnetite at 1,200 °C. Scanning electron microscopy with energy-dispersive X-ray spectroscopy indicated that Fe 0 particles, with a size of <10 μm, were highly dispersed on carbon particles to form an integrated anode (Fe 0 ) and cathode (C) structure of microelectrolysis filters. The effects of initial solution pH and Fe/C mass ratio on Cu 2+ removal were investigated. The extent of Cu 2+ removal increased from 93.53% to 99.81% as initial pH rose from 2.5 to 7.0. The residual Cu 2+ concentration was as low as <0.2 mg/L. The highest extent of Cu 2+ removal was achieved at Fe/C mass ratio of 6.8:1. The pseudo-second-order kinetic model fitted well for Cu 2+ removal by the ceramsite, revealing the chemisorption as a limiting step. The Cu 2+ adsorption equilibrium data were well described by the Langmuir isotherm, with a maximum adsorption capacity of 546.45 mg/g at initial pH 3.0.

Meeting the regulatory discharge standards for pulp and paper mill wastewater has become ever more difficult because of its recalcitrant and colored dissolved organic matter (DOM). In this study, the variation of DOM from the secondary effluent of pulp and paper mill wastewater before and after coagulation was investigated based on hydrophobicity/hydrophilicity, apparent molecular weight (MW) and fluorescence. DOM fractions of the secondary effluent were all with the apparent MW <20 kDa. Particularly, the hydrophobic acids (HOA) fraction, mainly composed of humic-like materials, was the major component, and it also had the highest color and SUVA254 (UV254 to dissolved organic carbon ratio). Hydrophilic bases (HIB) and hydrophilic neutrals (HIN) fractions were the other important parts besides HOA. Coagulation can remove all DOM fractions to different extent, and it was more effective for organic compounds with MW > 5 kDa. The removal efficiencies of humic-like, fulvic-like and soluble microbial by-product-like constituents in HOA and HIB fractions were much higher than in other fractions. Even so, the coagulation effluent still contained large amounts of contaminants with complicated fluorophores and apparent MW <5 kDa, and HOA and HIN fractions were also the major parts in the coagulation effluent. [ABSTRACT FROM AUTHOR]

Although in a critical position in the economy, the paper industry releases a lot of wastewater that requires adequate treatment for sustainable development. This study presents an application of Life cycle assessment (LCA) with the ReCiPe tool on the wastewater treatment plant (WWTP) of a paper factory in Vietnam to evaluate the environmental effect of the individual techniques in WWTP, especially the internal circulation (IC) reactor, a pioneer and practical anaerobic technology. Both Midpoint and Endpoint categories results demonstrated that chemical use and electricity consumption mainly contributed to the environmental impact in the WWTP. The Dissolved air flotation (DAF) and Moving bed biofilm reactor (MBBR) are classified as effective techniques to reduce the impacts on the environment. Moreover, the comparison of LCA between IC and up-flow anaerobic sludge bed (UASB) shows that IC is the better practically green technique for the environment.

Meeting the regulatory discharge standards for pulp and paper mill wastewater has become ever more difficult because of its recalcitrant and colored dissolved organic matter (DOM). In this study, the variation of DOM from the secondary effluent of pulp and paper mill wastewater before and after coagulation was investigated based on hydrophobicity/hydrophilicity, apparent molecular weight (MW) and fluorescence. DOM fractions of the secondary effluent were all with the apparent MW <20 kDa. Particularly, the hydrophobic acids (HOA) fraction, mainly composed of humic-like materials, was the major component, and it also had the highest color and SUVA 254 (UV 254 to dissolved organic carbon ratio). Hydrophilic bases (HIB) and hydrophilic neutrals (HIN) fractions were the other important parts besides HOA. Coagulation can remove all DOM fractions to different extent, and it was more effective for organic compounds with MW > 5 kDa. The removal efficiencies of humic-like, fulvic-like and soluble microbial by-product-like constituents in HOA and HIB fractions were much higher than in other fractions. Even so, the coagulation effluent still contained large amounts of contaminants with complicated fluorophores and apparent MW <5 kDa, and HOA and HIN fractions were also the major parts in the coagulation effluent.

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 R 2 = 0.7169; predicted R 2 = 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.

In recent years, the use of microalgae as feedstock for many marketable products, such as animal/aqua feeds, bioplastics and fertilizers, has gained renewed interest due to their fast growth potential coupled with relatively high lipid, carbohydrate and nutrient content. An algal biorefinery at an industrial site has the potential to sustainably and profitably convert carbon dioxide emissions into microalgal biomass and concomitantly reduce nitrogen and phosphorus from wastewaters. Industrial wastewaters are a potential alternative to traditional media used for large-scale microalgal cultivation. Pulp and paper mills are major consumers of water resources and discharge a huge amount of water to nearby lakes or rivers. This study investigated whether pulp and paper mill waste water is suitable for microalgal cultivation with the aim of achieving significant biomass production. Six different process waters from one Canadian pulp and paper mill were tested with two freshwater green microalgae. All of these waters were unable to support growth of microalgae due to inadequate nutrient concentrations, colour, turbidity and possible toxicity issues.

The effect of fly ash on biodegradability and methane production from secondary paper and pulp sludge, including its modeling, was evaluated. Three tests with fly ash concentrations of 0, 10 and 20 mg/L were evaluated at 32 °C. Methane production was modeled using the modified Gompertz equation. The results show that the doses used produce a statistically significant increase of accumulated methane, giving values greater than 225 mL of CH4 per gram of volatile solids (VS) added, and 135% greater than that obtained in the control assay. Biodegradability of VS increased 143% with respect to the control assays, giving values around 43%. The modified Gompertz model can describe well methane generation from residual sludge of the paper industry water treatment, with parameter values between those reported in the literature. Thus, the addition of fly ash to the process causes a significant increase of accumulated methane and VS removal, improving the biodegradability of paper and pulp sludge.

The porous metallic iron/carbon (Fe∘/C) ceramsites, with virtues of low cost and 'green' fabrication, were prepared by direct reduction roasting of magnetite, coal, and paper mill sludge. The X-ray diffraction data revealed that Fe∘ was generated in situ by reducing the magnetite at 1,200 °C. Scanning electron microscopy with energy-dispersive X-ray spectroscopy indicated that Fe∘ particles, with a size of <10 μm, were highly dispersed on carbon particles to form an integrated anode (Fe∘) and cathode (C) structure of microelectrolysis filters. The effects of initial solution pH and Fe/C mass ratio on Cu2þ removal were investigated. The extent of Cu2þ removal increased from 93.53% to 99.81% as initial pH rose from 2.5 to 7.0. The residual Cu2þ concentration was as low as <0.2 mg/L. The highest extent of Cu2þ removal was achieved at Fe/C mass ratio of 6.8:1. The pseudo-second-order kinetic model fitted well for Cu2þ removal by the ceramsite, revealing the chemisorption as a limiting step. The Cu2þ adsorption equilibrium datawerewell described by the Langmuir isotherm, with a maximum adsorption capacity of 546.45 mg/g at initial pH 3.0. [ABSTRACT FROM AUTHOR]