Search

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.

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 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.

The activated sludge process within the pulp and paper industry is generally run to minimize the production of waste activated sludge (WAS), leading to high electricity costs from aeration and relatively large basin volumes. In this study, a pilot-scale activated sludge process was run to evaluate the concept of treating the wastewater at high rate with a low sludge age. Two 150 L containers were used, one for aeration and one for sedimentation and sludge return. The hydraulic retention time was decreased from 24 hours to 7 hours, and the sludge age was lowered from 12 days to 2–4 days. The methane potential of the WAS was evaluated using batch tests, as well as continuous anaerobic digestion (AD) in 4 L reactors in mesophilic and thermophilic conditions. Wastewater treatment capacity was increased almost four-fold at maintained degradation efficiency. The lower sludge age greatly improved the methane potential of the WAS in batch tests, reaching 170 NmL CH4/g VS at a sludge age of 2 days. In addition, the continuous AD showed a higher methane production at thermophilic conditions. Thus, the combination of high-rate wastewater treatment and AD of WAS is a promising option for the pulp and paper industry. Funding agencies: Swedish Energy Agency [32802-2]; Scan-dinavian Biogas Fuels AB; Poyry AB; BillerudKorsnas AB; SCA; Fiskeby Board AB; Purac AB

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 (R 2 = 0.959, R 2 = 0.993 and R 2 = 0.969 for COD, phenol and Ca +2 removal, respectively, for EC and R 2 = 0.936, R 2 = 0.934 and R 2 = 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/cm 2 for EC, whereas in a 30 min trial, 74.31% of COD removal was achieved at pH 2 and current density 96 mA/cm 2 and H 2 O 2 /COD molar ratio 2.0 for EF. The operating costs were calculated to be 6.44 €/m 3 for EC and 7.02 €/m 3 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.

The aim of this paper is to prove the applicability of Auxipó as an auxiliary agent of coagulation for pulp and paper industry wastewater. Thus, it is possible to clarify the effluent more efficiently before launching it in waterbodies. To test the applicability of the auxiliary agent of coagulation, two coagulation and flocculation assay diagrams were developed: the first diagram only shows coagulant dosages, and the second diagram represents the coagulant and Auxipó dosage. Both tests demonstrated efficiency in turbidity removal; however, the results showed higher removal efficiency after the dosage of Auxipó.

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.

The reuse of wastewater by the pulp and paper industry reduces environmental impacts by contributing to raw water conservation, thereby making a greater volume of fresh water available for nobler purposes, and reducing wastewater treatment. This study evaluated a proposed system of water reuse at a Kraft pulp and paper plant in Brazil, based on a survey of water quality required by its consumption points, supplied by its water treatment plant. Results after ultrafiltration included: turbidity of 0,3 NTU and pH 7,5, average values of BOD 66,4 mg/L, COD 9,6 mg/L and the colour of 280,5 ppm Pt were measured after ultrafiltration. The ultrafiltered wastewater was considered available for reuse, and its quality was compared with that of the water supplied by the water treatment plant, which provided for the classification of potential reuse points. Water colour was identified as the limiting factor for reuse; thus the reuse points were two Kraft paper machines, and the water flow to the liquid ring formations that generate the vacuums inside nineteen pumps for these two machines. The advantages of this proposal for water reuse include: ultrafiltered water quality sufficient for the vacuum pumps, the small distance between the point of reused water generation and the paper machines section, and the reused water has no contact with the final product. The calculated cost and return time for the water reuse system was US$ 607.020,00 in 15 years.

The present paper presents the main results of the biodegradation study of paper industry wastewater through physico-chemical treatment. Indeed, around 60% of chemical oxygen demand (COD) removal can be achieved by electroflocculation treatment. Furthermore, a removal efficiency of the COD of almost 91% has been obtained by biological treatment, with activated amount of sludge for 24 h of culture. Concerning the physico-chemical pre-treatment of the untreated, filtered and electroflocculated rejection effluents, it has been investigated through the degradation curve of COD studies.

Aerobic biological treatment with activated sludge is the predominant process all over the world for treatment of pulp and paper industry wastewater. 50–70% of the biodegradable organic material is oxidized to CO2 and the rest is converted to bacterial biomass, typically termed as excess sludge or waste activated sludge (WAS). Handling and disposal of WAS in general and in particular from the pulp and paper industry face different processing difficulties, regulatory stringency due to organochlorine contamination and reluctance of people for reuse. With an objective of reducing the net disposable biomass, ozonation of WAS from a pulp and paper mill and from a laboratory scale batch activated sludge process operated with the wastewater and bacterial seed of the same pulp and paper mill have been carried out. With the mill sludge having predominant filamentous organisms 18% MLSS was reduced at an ozone dosage of 55 mg O3/g dry MLSS solid (DS) resulting in 2.5 times COD increase. With the laboratory sludge which is well structured and flocculating, only 6% MLSS was reduced at an ozone dosage of 55 mg O3/g DS. Ozonation mineralizes 26% and 20% AOX compounds embedded in the secondary sludge in the mill and laboratory sludge respectively at an ozone dosage of 55 mg O3/g DS. During ozonation, absorbed/adsorbed lignin on biomass was released which resulted in increased colour concentration. Ozonation can be a potential oxidative pretreatment process for reducing the WAS and paving the way for cost effective overall treatment of WAS.

The abnormal induction of anal fin elongation (masculinization) in female Gambusia was first reported in the 1980s for Florida streams receiving pulp and paper effluents. Although these early reports indicated masculinization responses that were similar to the complete development of a gonopodium (male secondary sex structure), additional evaluations throughout the 1990s demonstrated significant reductions in this response. These historic data suggested that mill process modifications may have been responsible for the reduced masculinization responses. The objective of the current study was to utilize Georgia Pacifics Palatka Mill to monitor a series of mill process modifications and their effects on masculinization responses in Mosquitofish (Gambusia). Gambusia were collected from upstream, discharge, and downstream sites in the Palatka Mill receiving stream (Rice Creek) and masculinization was evaluated. Collections were conducted annually during 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2008, and 2009, before and after a series of modifications which included: conversion to elemental chlorine free bleaching, conversion of secondary treatment to aerobic degradation, reduction of in-mill black liquor losses, addition of condensate stripping, reduction in water usage from 136 to 83 million litres per day (36 to 22 million gallons per day), installation of new brown stock washers, and oxygen delignification. Masculinization responses were evaluated using the anal fin index (ratio or anal fin rays 4 and 6). Reductions in this masculinization response were observed gradually across 1999 through 2009, with an absence of response in female Gambusia during 2004, 2006, and 2008 to 2009. These data indicate that pulp and paper mill upgrades and process modifications have resulted in the elimination of this biological response in Gambusia.

The goal of this study was to optimize the coagulation–flocculation process in wastewater generated from the paper and pulp industry using a grey relational analysis (GRA)-based Taguchi method. Process parameters included types and doses of natural coagulants and coagulant aid, and pH. To track the efficiency of the treatment process, the following responses were chosen for optimization: chemical oxygen demand (COD), total dissolved solids (TDS) and turbidity of wastewater, alone or in combination or all together. Analysis of variance showed that the type and dose of the coagulant aid were the most significant parameters, followed by pH and the dose of the coagulant; the type of coagulant used was found to be insignificant in the coagulation–flocculation process. Optimization of process parameters to achieve lower turbidity and greater removal of COD and TDS was verified in a separate confirmatory experiment, which showed improvements in COD and TDS removal and a decrease in turbidity of 8.2, 6.35 and 26.17%, respectively, with the application of the Taguchi method and GRA.

Pulp and paper mill effluents have been reported to cause changes in reproductive indicators of fish in laboratory and field studies. These changes include reduced egg production and gonad size, and altered hormone levels and expression of secondary sex characteristics. We examined the performance of biotreatment plants for their potential in abating effects of pulp and paper mill effluents on fish reproduction under laboratory conditions. A bleached kraft mill effluent (BKME) treated in an aerated lagoon and a thermomechanical pulp mill effluent (TMPE) treated by aerobic sludge in a sequential batch reactor were selected for study. Mature fathead minnows (Pimephales promelas) were exposed to effluents before and after biotreatment under continuous renewal conditions for 21 days. Egg production was monitored daily, while morphometric parameters (length, weight, gonad size), secondary sexual characteristics, and steroid hormone and vitellogenin levels were measured at the end of the effluent exposure. The effluent from both mills before biotreatment impaired the reproductive capacity of minnows (egg production) at concentrations of 10 and 20% vol/vol, but not at 2% vol/vol. Exposure to biotreated effluents from both mills at concentrations of 2, 10, 20, and 40% vol/vol caused no significant differences in overall reproductive capacity of minnows as compared with controls. These results indicate that biotreatment can significantly improve the quality of a BKME and an effluent from a TMP mill with respect to the reproductive capacity of fish as determined in laboratory tests.

Specific power consumption and reduction of BOD, COD, TS, pH, and chemical elements were used to determine the treatment efficiency of Fe, graphite and Al electrodes with alum and wood ash as supporting electrolytes on the effluent from a Kraft pulp and paper mill in Kenya. Five sampling points were selected along mill's effluent treatment system: primary settling tank (SP1), first aerated lagoon (SP2), second aerated lagoon (SP3), stabilization pond (SP4), and at discharge point (SP5). Operating costs were also compared between treatments. Graphite electrodes combined with alum showed the lowest power consumption (0.5 to 3.9 mWh/m3), followed by Al and Fe. All the electrodes reduced color from a maximum of 3,200°H to the minimum local standard of 15°H. However Al electrode with alum was the most effective method for BOD and COD reduction by over 60% and 58.8% respectively and generated less sludge at all sampling points. The cost of treatment was lowest with graphite electrode (US$0.006 to 0.0008 per m3 of effluent), but highest with Al electrodes combined with wood ash (US$31.74 to 8.34 per m3). Further study is required for the effectiveness of increasing the concentration of wood ash leachate at higher concentration and current density.

In the pulp and paper industry, the water use minimization is a constant target. One way to reduce water use is to recycle the effluent in a closed-cycle concept. In paper mills, the main source of liquid effluent is the so-called whitewater, which is the excess water, originated from pulp stock dewatering and other fibre contaminated water. This research studied the reuse of paper mill whitewater after membrane ultrafiltration (UF) in the paper machine and in the pulp bleach plant of an integrated mill. Contaminant removal and flux behaviour of the UF system were evaluated. The treatment by ultrafiltration was technically feasible and the treated whitewater had good potential to be reused in some processes in the paper machine. The reuse of ultrafiltered whitewater in the bleaching plant was not recommended because of the high level of soluble calcium present in this stream. Therefore, a combined treatment of the whitewater using the principle of precipitation and ultrafiltration was proposed showing good results and enabling the use of the treated whitewater in the bleach plant.

As opposed to effluents from chemical pulp production, very little is known about the endocrine potential of papermaking effluents. To evaluate the endocrine potential of biologically treated effluents from the main grades produced in Germany (fine, graphic and packaging papers), 16 samples were studied by means of the Recombinant Yeast Estrogen Assay (R-YEA). 10 samples were tested positive; seven of them were effluents from recovered paper processing mills. Possible sources of endocrine disruptors in addition to wood components include papermaking chemicals, paper converting chemicals, if recovered paper is used, and/or detrimental substances introduced by impurities in these chemicals. Six of the above samples were subjected to individual substance analyses to detect endocrinologically active or potentially endocrinologically active substances. Even though phthalate compounds were detected in concentrations between 0.46 and 2.36 μg/L, only two of the six samples were tested positive in the R-YEA, because the test fails to adequately detect this compound's class. Despite this drawback, the R-YEA will be used for further studies because of the great variety of potential endocrine substances present in paper mill effluents. In particular, mechanical and recycled fibre pulps as well as the constituents of chemical additives must be investigated in more detail.

Ultra- and nanofiltration with high shear CR-filters have been utilized for cleaning of clear filtrates and effluents from the pulp and paper industry. The aim was to find out how different nanofiltration membranes operate at high shear conditions. The filtration efficiency of the membranes was evaluated by measuring flux, retention and fouling at various recovery and pH conditions. High fluxes (∼100 L/(m2h)) for nanofiltration membranes were measured when circulation waters from the paper machine were filtered at neutral conditions. In the filtration of discharge of external activated sludge treatment plants we measured fluxes around 150 L/(m2h) even at a concentration factor of 12. The best NF membranes removed over 80% of the organic carbon and of the conductivity and almost completely eliminated the color. With acidic waters fluxes and retentions were significantly lower. The NF270 membrane from Dow and the Desal-5 membranes from Osmonics had the highest flux and retention properties. However, the Desal-5 membrane lost its retention properties slowly, which restricts its use in the high shear CR-filter. CR-nanofiltration can be used in the pulp and paper industry without feed pre-treatment by ultrafiltration. This increases the attractiveness of high shear CR-nanofiltration.

Colour discharges are gaining renewed focus in the pulp and paper industry as increasingly strict regulatory limits are placed on wastewater quality and aesthetics. In-mill process improvements, such as ECF bleaching and oxygen delignification, have decreased wastewater colour loadings. However, a survey of 12 pulp and paper mill systems found that effluent treatment using aerated stabilisation basins (ASB) leads to average increases in colour of 20-40%. In some instances, this phenomenon may even double the influent colour levels. Activated sludge systems did not produce a colour increase. The measured increases that follow ASB secondary treatment may be sufficient for a mill to fail prescribed discharge standards. A detailed field survey focusing on sections of an integrated bleached kraft mill ASB treatment system was undertaken. The average increase in colour at the final point of discharge was 45%. The major changes in colour concentration occurred in the inlet to the main treatment pond, and in polishing ponds that followed the main treatment pond. Both of these areas receive little or no aeration. No significant change was observed in the highly aerated main pond. These results, along with literature reports, suggested that redox conditions play a major role in influencing colour behaviour. To test this, two series of paired continuously stirred reactors were used to treat whole mill effluent from two ECF bleached kraft mills in parallel. The first series initially treated under anaerobic conditions, followed by an aerobic reactor, while the second series reversed this order. With the initial anaerobic stage, effluent colour increased by 18% and 19% for the first and second series respectively. Subsequent treatment by aerobic bacteria further increased colour by 14% and 6%, for a total increase of 32% and 25%. Initial aerobic treatment, however, did not lead to any significant change in colour for either effluent. Further anaerobic treatment following aerobic conditions produced only small increases in colour. These results are consistent with the ASB and activated sludge system survey, suggesting that anaerobic conditions at the head of treatment systems initiate the observed increases in effluent colour in ASB treatment systems.

The effect on fish reproduction of final treated effluent from a thermomechanical pulp mill in Saint John, New Brunswick, Canada, was studied using mummichog (Fundulus heteroclitus), an endemic fish species of the Atlantic coast of North America. A 1997 artificial stream study at the same mill showed a reduction in gonad sizes in mummichog after a 28-day exposure to 3% final treated effluent. In 2005, we reevaluated final treated effluent, and conducted a toxicity source evaluation to identity waste stream sources within the mill that may cause reproductive effects. Relative to reference, no significant differences in gonad size, plasma levels of gonadal sex steroids, egg production, or stage of egg development were observed in fish exposed to 1, 3, 10, 30, and 100% final treated effluent or in-mill waste streams. Unlike the previous study in 1997, these data indicate a low potential for an effect of final effluent on fish reproduction. Since the 1997 study there were no major process changes that could explain the differences in the results. However, there was high variability in gonad size, egg production, and endocrine endpoints measured in the more recent test, which resulted in low power to detect differences. This has prompted research to refine the current reproductive test by optimizing study design.

The objective of this work was to evaluate the semi-continuous post-treatment of anaerobically-pre-treated weak black liquor (anaerobic effluent, AnE) by aerobic post-treatment using hybrid pellets of Trametes versicolor. The latter consisted of fungus immobilized onto holm oak sawdust (mixed or double pellets) or a mixture of holm oak sawdust and powdered activated carbon (triple pellets). First, a semi-continuous experiment was run to compare the effectiveness of triple and mixed pellets in agitated flasks for 15 cycles of 7 days each. A second extended batch test was implemented with 500 mL AnE and triple pellets to give 400 mg fungal biomass; some units were spiked with protease inhibitor. In the first experiment, triple pellets displayed consistently higher removal efficiencies of pollutant parameters than double pellets (10 to 15% higher), although overall averages were moderate and no statistical significance to the difference could be set because of the noise of fluctuations. Periodic fluctuations of removal were characterized by three periods of approximately six cycles each with maximum removals occurring at cycles 3–4, 7–9, 13, and 14. Evaluating pooled removals of the latter cycles showed that triple pellets were significantly more effective than double pellets, with removal efficiencies as high as 47% of COD, colour, and absorbance at 254 nm (A254). In general, protease activity seemed to increase in the third period (last six cycles), whereas activities of MnP, LiP and Lac significantly decreased. In the second experiment, pollutant removals and enzymatic activities of triple pellets with protease inhibitor were significantly higher than those of units without added protease inhibitor. These results indicate that protease could be the main cause of periodic falls of pollutant removal efficiencies found in the first experiment.

This paper reviews nutrient issues within the pulp and paper industry summarising: nitrogen and phosphorus cycles within treatment systems; sources of nutrients within pulping and papermaking processes; minimising nutrient discharge; new approaches to nutrient minimisation; and the impact of nutrients in the environment. Pulp and paper industry wastewaters generally contain insufficient nitrogen and phosphorus to satisfy bacterial growth requirements. Nutrient limitation has been linked to operational problems such as sludge bulking and poor solids separation. Nutrients have been added in conventional wastewater treatment processes to ensure optimum treatment performance. Minimising the discharge of total nitrogen and phosphorus from a nutrient limited wastewater requires both optimised nutrient supplementation and effective removal of suspended solids from the treated wastewater. In an efficiently operated wastewater treatment system, the majority of the discharged nutrients are contained within the biomass. Effective solids separation then becomes the controlling step, and optimisation of secondary clarification is crucial. Conventional practice is being challenged by the regulatory requirement to reduce nitrogen and phosphorus discharge. Two recent developments in pulp and paper wastewater treatment technologies can produce discharges low in nitrogen and phosphorus whilst operating under conventionally nutrient limited conditions: i) the nutrient limited BAS process (Biofilm-Activated Sludge) which combines biofilm and activated sludge technologies under nutrient limited conditions and ii) an activated sludge process based on the use of nitrogen-fixing bacteria. Aerated stabilisation basins often operate without nutrient addition, relying on settled biomass in the benthal zone feeding back soluble nutrients, or the fixation of atmospheric nitrogen. Thus effective nutrient minimisation strategies require a more detailed understanding of nutrient cycling and utilisation. Where it is not possible to meet discharge constraints with biological treatment alone, a tertiary treatment step may be required. In setting nutrient control guidelines, consideration should be given to the nutrient limitations of the receiving environment, including other cumulative nutrient impacts on that environment. Whether an ecosystem is N or P limited should be integrated with wastewater treatment considerations in the further design and development of treatment technology and regulatory guidelines. End-of-pipe legislation alone cannot predict environmental effects related to nutrients and must be supplemented by an effects-based approach.

Thermophilic aerobic treatment of settled pulp and paper mill effluent was studied under mill premises with two comparative pilot processes; suspended carrier biofilm process (SCBP) and activated sludge process (ASP). Full-scale mesophilic activated sludge process was a reference treatment. During the runs (61 days) hydraulic retention times (HRTs) were kept 13 ± 5 h and 16 ± 6 h for SCBP and ASP, respectively. Corresponding volumetric loadings rates (VLR) were 2.7 ± 0.9 and 2.2 ± 1.0 kg CODfilt m-3d-1. Temperatures varied between 46 to 60°C in both processes. Mesophilic ASP was operated with HRT of 36 h, corresponding VLR of 0.7 kg CODfilt m-3d-1. Both SCBP and ASP achieved CODfilt (GF/A filtered) removals up to 85%, while the mesophilic ASP removal was 89 ± 2%. NTU values were markedly higher (100-300) in thermophilic effluents than in mesophilic effluent (30). Effluent turbidity was highly dependent on temperature; in batch experiment mesophilic effluent sample had NTU values of 30 and 60 at 35°C and 55°C, respectively. As a conclusion, both thermophilic treatments gave high CODfilt removals, which were close to mesophilic process removal and were achieved with less than half of HRT.

Photocatalytic oxidation (PCO) is a promising technology for purification of biological pretreated wastewater or destruction of non-biodegradable compounds. For this reason PCO has been investigated as a last step of purification of biologically pre-treated paper-mill effluents. The influence of the parameters pH, TiO2-modification, TiO2-concentration, catalyst re-use, concentration of substances to be oxidised (wastewater quality) has been determined. The TOC of the biologically pretreated wasterwater was up to 55 mg L-1. This wastewater was treated with a previously presented aerated cascade photoreactor which was modified for batch experiments. A high specific oxidation rate of up to 0.76 g TOC m-2 h-1 as well as a complete TOC mineralization has been achieved after the optimisation of the process parameters. The complete destruction of recalcitrant compounds will offer the opportunity to reuse the wastewater in the production process. The increase of the BOD5/TOC ratio after a short irradiation period indicates the transformation of recalcitrant organic compounds to better biodegradable intermediates. The use of PCO as a pre-treatment step for the enhancement of the biodegradability of wastewater, containing recalcitrant or inhibitory compounds is an alternative to a long and energy-intensive total pollutant mineralization.

Fathead minnow (Pimephales promelas) lifecycle tests have been used to assess the effects of many North American pulp mill effluents. Fish are exposed under controlled laboratory conditions to final effluent, from the egg stage through hatching, juvenile stage and mature adult stage. Outlined here are methods for the lifecycle test (which takes from 4 to 5 months to complete) with sampling of juvenile fish at 1, 2 and 3 months of age, and sampling of mature adults after breeding. The results of most fathead minnow lifecycle studies have shown that pulp mill effluents cause metabolic and reproductive disruption (enlarged livers, reduced egg production, smaller gonads, decreased sex hormones and reduced secondary sex characteristics). Thus, the fathead minnow lifecycle assay is able to mimic the most commonly observed changes seen in wild fish exposed to pulp mill effluents. Sensitive indicators of reproductive effects in fathead minnows exposed for a lifecycle to pulp mill effluents include secondary sex characteristics, time to first reproduction and number of eggs laid. Egg production is often the most sensitive response to pulp mill effluents. Because of the length and cost of full lifecycle tests, a shortened assay using adult fish was developed as a screen for endocrine-disrupting compounds. This assay, the terminal reproduction test, has been used with success on a few pulp mill effluents. The assay exposes fathead minnow breeding pairs for three weeks to effluent, and compares egg production, sex characteristics and bioindicators of reproductive performance in pre-exposure versus post-exposure fish. For assessment of pulp mill effluents, it appears that the sensitivity of the shortened terminal reproductive fathead minnow assay may be improved by assessing bioindicators of reproductive performance (such as circulating levels of sex hormones, and circulating or hepatic vitellogenin) along with changes in secondary sex characteristics and egg production.

The aim of this research was to study the effects of chemical spills on activated sludge metabolic activity and settleability. On-site, laboratory-scale tests were carried out at three pulp and paper mill activated sludge plants. Oxygen uptake rate (OUR) and dissolved organic carbon (DOC) removal were used for monitoring of metabolic inhibition. The effects of chemicals on 30-min settled sludge volume were studied. Accidental release reports from five pulp and paper mills were analysed. Thirty-four chemicals were selected to the laboratory tests. Of the tested chemicals 2 biocides, monochloro acetic acid, soft soap and turpentine inhibited the OUR of the sludge and thus, had an acute toxic effect on the activated sludge. The biocides and disperging agent reduced DOC removal. Aluminium sulphate and optical brightener had a negative effect on sludge settleability and thus, they may cause losses of activated sludge from treatment plant. In conclusion, maximum possible spill of the five chemicals may reduce the performance of the activated sludge.

A survey of the concentrations of nonylphenol ethoxylates (NPnEO) and their metabolites in the primary and secondary treated effluent and sludge samples collected from pulp and paper mills was conducted. Through the coordination of the Pulp and Paper Research Institute of Canada (PAPRICAN), 19 Canadian and one U.S. mill of various process types and waste treatment methods supplied samples in this study. Previously developed solid-phase extraction, supercritical fluid extraction, high performance liquid chromatography and gas chro-matography/mass spectrometry methods were used for the determination of NPnEO and their metabolites, nonylphenol (NP) and the carboxylates (NPEC), in effluent and sludge samples. The levels of NPnEO ranged from

The occurrence of filamentous bacteria was investigated in 15 French pulp and paper activated sludge wastewater treatment plant (WWTP). Large filamentous populations were present in most of the plants. Identification carried out with conventional methods based on morphological features and staining techniques showed that the four main filamentous bacteria encountered in these industrial WWTP and responsible for bulking belong to the genera Thiothrix sp., Type 021N, Haliscomenobacter hydrossis and Type 0092. During two years a specific survey was performed for three of these WWTP showing recurrent bulking phenomena. Data from WWTP performance, chemical data and filaments characterization were compared to correlate the presence of specific filaments with process operating conditions.

A TAML® catalyst (0.5 μM, 0.23 mg/L of effluent) combined with hydrogen peroxide (6.5 mM, 0.19 g/L of effluent) were capable of permanently removing 46% of the colour from bleach plant effluent (Eop, pine-derived) in one hour at 5,000 L effluent per day. Increasing concentrations to 2 μM catalyst (0.9 mg/L of effluent) and 22 mM peroxide (0.75 g/L of effluent), resulted in removal of 78% of the colour. In addition, 29% of the chlorinated organic material (AOX) was also removed. A laboratory investigation indicated that the oxidative process predominantly removed phenolic structures. The low aromatic content of the effluent meant that the majority of the organic material was not substantially altered during treatment. Thus chemical oxygen demand was essentially unchanged. This technology was able to remediate colour from effluents derived from both softwood (pine) and hardwood (eucalypt). Laboratory studies on catalyst life-time during effluent treatment, demonstrated that activity was maintained for a sufficient period to eliminate all the chromophore available to the active species, but that the catalyst did not survive long enough to be discharged into the receiving environment. Microtox tests showed that catalyst degradation products were not toxic to the receiving environment.

Wet oxidation (WO) is a well established process for purification of concentrated municipal and industrial wastewaters. Many attempts have been made to modify the WO process or to create a suitable combination of processes. This work was undertaken to investigate wet oxidation integrated with coagulation, i.e. to treat the sludge remaining after coagulation with a WO process. The possibility of regeneration of the used coagulant was also considered. Two waters from paper mills were used: TMP (thermomechanical pulp) circulation water and membrane concentrate. About 50% of the COD in the original water can be removed by coagulation using Fe2(SO4)3. The results from the wet oxidation experiments show the positive effect of iron in the chemical sludge as a catalyst. The efficiency of the WO process was enhanced almost by 100%. The remaining dissolved organic matter can be easily removed biologically.

In this paper we briefly describe pinch technology as a practical tool for effective energy management in the pulp and paper industry. Results indicate good steam savings. Recently pinch technology has been extended to water management. We have developed a customized methodology for the pulp and paper industry, to eliminate or reduce fresh water intake. Although the methodology is not fully developed it is a “proof of concept” that pinch principles can be applied to water related problems. The eventual combination of both thermal and water pinch will thus provide a structured and comprehensive approach for plant wide efficiency increase.

A question raised again and again over many decades by pulp and paper mill personnel and local authorities in many countries is, "Does the finding of large numbers of coliform enteric bacteria in the mill water or biotreatment system indicate a real health hazard for the mill workers or the downstream public?" Some of the difficulties in answering this question arise from the widespread misunderstanding of what coliform indicator (enumeration) tests can tell us. Increasing scientific understanding over the last 30 years has greatly altered the coliform indicator tests, the types of bacteria enumerated, and our ability to distinguish harmless from pathogenic (disease-producing) bacteria. This brief review discusses our current understanding of where and when it is appropriate to use coliform indicator assays and the meaning of the results.

Anaerobic bioconversion of newsprint and waste office paper was performed in bench-scale reactors with three inocula sources: landfill, rumen, and anaerobic digester. Office paper bioconversion was nearly complete within 20 days but continued for about 165 days with methane yield efficiencies ranging from 71–85% of potential chemical oxygen demand (COD) conversion. Average newsprint methane conversion efficiencies ranged from 32–41% of total COD under strictly anaerobic conditions for 300 days. Mass balance calculations revealed that more than 80% of newsprint cellulose was biodegraded. The apparent limiting factor for anaerobic bioconversion of newsprint was the physical association between lignin and cellulose. After proper acclimation, the three inocula tested equally well for methane production under strictly anaerobic conditions. Testing of ground, shredded strips, and whole paper pieces showed no effects of feedstock size on bioconversion rate or extent. Alkali pretreatment with NaOH concentration up to 10% significantly improved newsprint biodegradability. Treatment for longer duration or at elevated temperatures increased the solubilization of lignin, but did not improve bioconversion of newsprint to methane. Neutralizing treated samples with carbon dioxide gave higher methane yields compared to sulfuric or hydrochloric acids, suggesting that digester neutralization could be combined with biogas scrubbing.

The feasibility of aerobic vessel composting and anaerobic digestion for the treatment of pulp and paper mill sludges were studied. The composting studies made use of primary and secondary sludge from a de-inking and paper mill. In six parallely aerated 500 1 vessels with various carbon : nitrogen (C:N) -ratios, the most optimal performance was obtained with C:N -ratios of c. 22–35, while higher and lower ratios delayed the temperature increase. With the optimal ratios, the thermophilic stage was reached within 36 h, and the stage lasted for about seven days. In the scale-up study (18 m3 compost vessel), the thermophilic stage was reached within 24 h. An effective dehydratation of the mass was obtained as the total solids (TS) content of the compost increased from 31.3– to 63.8– within 21 days. The anaerobic digestion of pulp and paper mill sludges was studied using two mesophilic 5 1 digesters, their feed sludges consisting of a mixture of municipal sewage sludge and primary and secondary sludge from a pulp and paper mill. With this feed mixture and with a loading rate of about 1.0 kg volatile solids (VS)/m3d a removal of about 27 to 40– VS and methane production of about 180 1/kgVSadded feed sludge were achieved during the 80 d study period. The study showed that pulp and paper mill sludges are amenable to both aerobic composting and anaerobic digestion.

As part of an extensive audit of the Alkaline-Peroxide Mechanical Pulping (APMPTM) plant at the Malette Quebec Inc. mill in St. Raymond, Que., effluents were sampled from various stages of the process for comprehensive chemical characterizations, aquatic toxicity testing and anaerobic biotreatability assessments. In addition, untreated and secondary treated combined effluent from the integrated paper mill were sampled to determine the effectiveness of a conventional activated sludge process at the mill site. During the one-day sampling period, the APMP plant processed a mixed wood furnish consisting of 50% spruce/balsam fir and 50% aspen, with a chemical charge of 3.5% sodium hydroxide and 3.8% hydrogen peroxide on oven-dry fibre, while the Machine Finish Coated (MFC) paper production rate was 100 odt/d (oven dry metric tonnes per day). Measured production-specific contaminant discharge loadings from the novel APMP process were 56 kg BOD5/odt and 155 kg COD/odt in a combined effluent flow of 28 m3/odt. Sources of process effluent were chip washing, three stages of wood chip pretreatment and chemical impregnation (i.e., Impressafiner stages), interstate washing and pulp cleaning. The three Impressafiner pressates were found to be the most concentrated (i.e., 12-26 g COD/L) and toxic streams. Microtox testing of the pressates revealed EC50 concentrations of 0.07-0.34% v/v. The warm and concentrated effluents generated by the non-sulphur APMP process were found to be highly amenable to anaerobic degradation as determined by batch bioassay testing. Filterable BOD5 and COD(f) of the process effluents were reduced by 87-95% and 70-77%, respectively, with corresponding theoretical methane yields being attained. Acid-soluble dissolved lignin compounds exhibited biorecalcitrance, as revealed by limited removals of 34-55%, and were the main constituents contributing to residual COD(f), while resin and fatty acids (RFA) were reduced by 80-94%. The conservatively operated full scale activated sludge treatment process achieved a similar high 74% COD(f) removal from the whole mill effluent, while BOD5 and RFA reductions were virtually complete and the treated effluent was non-toxic, as measured by Microtox.

Rainbow trout exposed to effluent from a UNOX (oxygen activated sludge) treatment plant were found to exhibit signs of distress during the first hours of exposure. While the final effluent was not acutely lethal at full strength, it was still important to determine the cause of the distress to ensure that the mill's effluents remain in regulatory compliance. The use of a series of effluent manipulations involving pH adjustment and aeration as well as observations of symptoms exhibited by the fish were successful in identifying carbon dioxide as the cause of fish distress for the UNOX-treated effluent. For rainbow trout, the symptoms of exposure to elevated levels of carbon dioxide of 100 mg/L or greater included loss of equilibrium, erratic swimming, gasping at the surface, sinking to the bottom of the test container and paralysis. The fish were found to eventually recover as the carbon dioxide was stripped from the effluent due to aeration during the test. A carbon dioxide concentration of 250 mg/L, however, was found to be lethal to trout A survey of mills using oxygen activated sludge treatment systems indicated that the carbon dioxide levels in effluents from such operations can range from 48 to 251 mg/L. Solutions for eliminating the fish distress and possible mortality associated with such effluents would be to lower the carbon dioxide level to below 100 mg/L by aeration or pH adjustment.

In this paper, elimination of color from the effluents of the secondary stage biological treatment plant of an integrated pulp and paper mill located at a tourism resort was investigated by using a marine outfall system. The investigated mill has a full-scale aerated lagoon system treating effluents from a chemical pre-treatment plant. The colored effluents from the treatment plant have been discharged to a river ending in the Mediterranean and this has resulted in deterioration of the natural appearance of the coastal waters used for recreational purposes. In this study, a marine outfall system with a diameter of 1200 mm and a multiport diffuser of 290 m were planned to eliminate the color problem from the lagoon effluents. The required initial dilution to reduce the color to unnoticeable levels in the marine environment was determined 70 by laboratory-scale dilution experiments. In addition to these investigations, long-term full scale treatment results of the related industry are presented. Oceanographic studies and water quality measurements were performed to evaluate the effects of effluents from the industry on the marine environment. Bioassay tests were also conducted to assess the toxic impacts of the secondary treatment effluents on the macro fauna using Lapistes retucularis as a test species. Considering these findings, a marine outfall system was designed. The designed marine outfall system is currently under construction.

An advanced treatment process was developed during the last five years to improve the treated effluent quality in view of stronger environmental regulations and the possibility for the reuse of treated effluent in the Pulp and Paper Industry. The combination of ozone with fixed bed biofilm reactors is one of the most efficient tertiary effluent treatment processes to give maximum elimination of COD, colour and AOX with a minimum of ozone dosage. Several laboratory and pilot tests with effluent from a full biological treatment works confirmed the expected targets. Ozone diffusion parameters, i. e. bubble size, and distribution, reaction time and hydrodynamic pattern are decisive for interface/film or bulk reaction. This is the key economic factor for the elimination of certain kinds of organic matter by transferring persistent “hard” COD into biodegradable compounds (BOD). Two-stage ozonation with intermediate biodegradation proved to be a valuable tool for obtaining high COD elimination efficiencies in the tertiary treatment of effluent with high persistent COD concentrations. A fully equipped bench scale plant using the ozonation - biofiltration process is in operation since the beginning of 1998. A separate batch ozonation system allows tests for optimisations which are difficult to perform in a continuous process. Results with papermill effluent are presented. This equipment gives results sufficient for determination of design parameters for an industrial size.

Activated sludge systems operated under alkaline conditions remove EDTA. To improve EDTA removal a better understanding of EDTA biodegradation and its intermediates as well as knowledge of kinetic parameters are a prerequisite. Activated sludge appeared to degrade EDTA via ethylenediaminetriacetate (ED3A). The sludge was able to split ED3A into readily biodegradable iminodiacetic acid and iminoacetaldehydeacetate. The maximum growth rate of EDTA-grown sludge was approximately 0.15 days−1. The Km for EDTA and maximum oxidation rate of EDTA-grown sludge were 10 mg/L and 135 mg O2 g−1 SS day−1. Specially cultivated activated sludge degraded EDTA under neutral conditions and was capable of degrading the FeEDTA complex at a low rate. Bioaugmentation of EDTA-grown sludge enabled EDTA removal in a treatment system under neutral conditions.

Lab-scale have been made with an aerobic selector followed by an aerated reactor. Sulphate mill effluent and waste paper mill effluent were used during the tests. It was verified that the treatment system could produce a sludge with an SVI below 140 ml/g and a high COD-reduction. It was also found that a high fraction of the COD was reduced as uptake and storage in the selector. The COD was thereafter oxidized in the aerated reactor. Full scale plants have been studied where aerobic selectors are used. The plants produce a sludge with a stable SVI below 150 ml/g. This enables a stable function regarding COD-reduction at varying loading conditions and at frequent product quality changes.

The effects of synthetic polymer (HE, PEI, and PAM) and natural polymer (chitosan) and chemical (alum) coagulant on the removal of lignin (black liquor color, and TOC) from pulp and paper industrial wastewater were investigated. It was observed that the formation of flocs was rapidly taking place which was an indication of fast coagulation flocculation process. PAM which is a nonionic polymer had poor effect as compared to HE and PEI which are cationic polymers. Both HE and PEI resulted in good brown colored precipitate at pH of about 6. These coagulant resulted in removal of about 80% of color and 30% of TOC from alkaline (black liquor) wastewater by gravity settling in 30 minutes. alum resulted in good precipitate with less than 30 minutes settling time by gravity. The percent color removed by alum was the same as the one removed by HE or PEI, but the TOC removed was higher by this chemical coagulant (about 40%). The natural coagulant, chitosan, resulted in the highest removal in both color and TOC as compared to both synthetic polymers and chemical coagulant. Up to 90% of color and 70% of TOC were observed to be removed by chitosan.

The results achieved on industrial effluents from four different paper mills, ranging from highly diluted effluents from units for the production of fine papers using bleached cellulose, to much more concentrated effluents from an integrated pulp and paper plant, show the potential and advantages of the Biofor process. Implemented as a complement to or replacement for activated sludge systems, the BioforR process, which dispenses with the clarification step and offers excellent resistance to sudden load and flow rate variations, is particularly well suited to the needs of this industry. This explains the rapid success already achieved in Europe and expected soon in North America.

A new moving bed biofilm reactor (MBBR) has been developed, where the biomass is attached to small plastic elements that move freely along with the water in the reactors. Pilot-tests with these new biofilm reactors, have been performed at four different pulp and paper mills. The wastewaters tested were paper mill effluent, bleachery effluent, NSSC effluent and a mixture of CTMP and ground wood effluents. Good results were obtained with all the different wastewaters. These results are presented and discussed, together with full-scale design data for the MBBR treatment plants constructed at two of the mills.

A new regulatory system known as integrated pollution control (IPC) is being introduced in the UK over the period 1991-1996. This will apply to combustion processes, some coating processes and some pulp and paper mill processes. Prescribed processes will have to use control concepts based on “best available techniques” and optimisation of waste streams released to the different receiving media. BAT standards have been set for the combustion processes, but not yet for the pulping and papermaking processes. The main types of UK mill that could be affected by this new regime are non-integrated paper mills, which use imported pulp and/or wastepaper. If prescribed under IPC, mills will have to justify their raw materials/process selection and pollution abatement technologies in terms of minimising impacts to air, water and land.

The focus of this paper is on the earlier, recent and future developments in closing the water circuits in pulp and paper production. During the 1960s the U.S. pulp and paper industry was in its environmental infancy concentrating mainly on removal of settleable solids and initiating river assimilative capacity studies. The 1970s began with environmental legislation having enforceable powers to achieve primary and secondary (biological) treatment which was fundamentally fulfilled during the 1980s. The late 1980s and early 1990s opened with toxicity becoming the major environmental issue as measured mainly by absorbable organic halogens (AOX) and dioxins. This paper identifies progress and key technological developments towards furthering stringent environmental enhancement and provides additional knowledge requirements leading into the next century.

Recent advances made in the reuse of pulp and paper industry sludges in hardboard production are explained. Data obtained from pilot and full-scale plants using primary sludge of a pulp and paper industry as an additive in the production of hardboard is presented. An economic analysis of the reuse of pulp and paper primary sludge in hardboard manufacturing is given. The quality of the hardboard produced is tested and compared with the qualities of the hardboard produced by the same plant before the addition of primary sludge. The hardboard with primary sludge additive has been used in Turkey for about a year in the manufacturing of office and home furniture. The results are very satisfactory when the primary sludge is used at 1/4 ratio.

The kraft pulp and paper industry is currently faced with the challenge of substantially reducing the discharge of conventional and toxic pollutants to the receiving environment without compromising its competitiveness. Ultrafiltration (UF) and nanofiltration (NF) are among the various unit processes that are being investigated by researchers interested in developing alternative schemes for meeting this challenge. The objectives of the work presented here were: (i) to review the potential uses for UF and NF in the kraft pulp and paper industry and (ii) to evaluate the performance of eleven UF and NF membranes using a caustic extraction stage effluent from a kraft mill pulping softwood with a O D55/C45 EO H D bleaching sequence. The experimental work was conducted with two flat-sheets bench-scale units fed in parallel: a low shear and a high shear unit. The most promising UF membrane gave an average permeate flux of 9 m3m2d for a volume reduction factor (VRF) of 30, under high-shear conditions at 0.69 MPa. The associated COD rejections ranged from 85%–90% at a VRF of 1 down to 70–75% at a VRF of 30. While the results demonstrated in this study show promise, further research is needed to demonstrate the cost effectiveness of both high-shear and low-shear equipment for this application as well as options for the reuse or treatment of the diluted and concentrated streams produced by the UF/NF systems.

This research examined the impact of ozonation on lignin-derived and aliphatic compounds ratio (L/A ratio) in secondary pulp and paper mill effluents. Afterwards, adsorption process was employed to investigate the adsorption behavior of ozonized compounds on granular activated carbon (GAC). Phenol and isopentanoic acid (IPA) were practically used as substitute of lignin-derived and aliphatic compounds, respectively. The paper presents the results obtained at laboratory scale with ozone and GAC adsorption as a mean to obtain effluents suitable as reclamation for pulp and paper industry, which requires very stringent limitation in terms of DOC and color removal. The conversion of recalcitrant nature of pulp and paper mill wastewater had been moderate in term of L/A ratio after time interval of ozonation. After ozonation pre-treatment, the adsorption experimental was performed to investigate the adsorption behaviors of phenol and IPA from aqueous solutions onto GAC compared with the decolorization behaviors in real effluents. The best isotherm models fitted to phenol and IPA adsorption on PPHO were determined in the order of Ridlich-Peterson isotherm > Langmuir isotherm > Freundlich isotherm. The IPA was adsorbed strongly on GAC as compared with phenol due to its properties. The maximum adsorption capacity of phenol and IPA on GAC were 0.32 g.g-1 and 0.65 g.g-1, respectively. As result in real effluents, the adsorption capacity of color from the ozonized effluents on GAC was 132.93 ADMI unit.L/mg which was much higher than those of non-ozonized effluents (78.78 ADMI unit.L/mg) and synthetic lignin solutions (55.97 ADMI unit.L/mg).

The agro-residue based pulp and paper industry generates high strength and high volume wastewaters, which in the absence of techno-economically viable chemical recovery systems and cost-effective pollution control systems pollute the recipient environment. The use of the “end of pipe” treatment approach results in a complex wastewater system and imposes a very high economic burden on these units. A more pertinent approach is to incorporate “at source” pollution prevention measures prior to the design of the end-of-pipe wastewater treatment facility. This cleaner production/waste minimisation approach not only results in direct financial returns in the form of material conservation and recovery/reuse of fibres but also reduces the overall investment and annual operational costs of the subsequent wastewater treatment system. Studies at four paper mills where appropriate technologies for waste reduction and handling, and energy conservation have been demonstrated and implemented, are presented. The paper highlights the various in plant measures viz. process modification and recovery/recycle/reuse of resources, which can be used to reduce the total pollution load. These measures lead to increases in profit margin of up to 20% and reduced wastewater treatment costs of up to 30%. To illustrate this approach, a case study in a 25 TPD mill has been discussed.