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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.

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.

This study examined the responses of a population of brook stickleback (Culaea inconstans) exposed to pulp mill effluent at Jackfish Bay, Lake Superior, Canada, in May 2007 and May 2011. Brook stickleback were extirpated from the effluent-receiving site, presumably due to anoxia after this period. Females at the effluent-receiving site had significantly larger gonad sizes in 2007 and 2011. In 2011, effluent-exposed female gonadal development was significantly advanced when compared with reference sites; they were the second most mature when compared among three different reference sites. Analysis of 7-ethoxyresorufin-O-deethylase activity revealed that effluent-receiving site females had greater CYP1A induction in 2007 and significantly greater CYP1A induction in 2011. Effluent-receiving site males showed significantly reduced CYP1A induction in 2007 and significantly greater induction in 2011. Chemical evaluation of sediment from the receiving environment showed elevated levels of resin acids and the polycyclic aromatic hydrocarbon, retene. Higher condition factors and more mature gonads were consistent with higher winter and spring temperatures modified by effluent or by lake vs. stream environments. Overall, effects on effluent-exposed brook stickleback were not consistent with reported effects in white sucker exposed to the same effluent in previous studies. This article has been made Open Access thanks to the kind support of CAWQ/ACQE (https://www.cawq.ca).

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 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 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.

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.

In this work, titanium dioxide (TiO2) was modified with reduced graphene oxide (rGO), and then coated on filter paper to prepare the rGT/FP photoelectrode for the photoelectrocatalytic (PEC) decolorization of methylene blue (MB). The physicochemical properties of the rGT/FP photoelectrode were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and UV-Vis diffuse reflectance spectroscopy (DRS). The decolorization results demonstrated that the photocatalytic (PC) and electrocatalytic (EC) efficiency of the photoelectrode could be significantly improved by the modification of rGO. The improvement of PC and EC efficiency might attribute to the existence of rGO, which could extend the light-harvesting efficiency, promote the photocurrent response value and suppress the charge recombination. Furthermore, the PEC decolorization of MB using the rGT/FP photoelectrode presented higher efficiency than the sum of PC and EC decolorization, indicating the synergistic effect between the photo and electrical energy.

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 essay outlines the use of an anaerobic baffled reactor (ABR) treating pulp and paper wastewater during its start-up period. For this purpose, a pilot with four chambers and overall volume of 45 liters was fed continuously through the equalization tank of Mazandaran wood and paper wastewater treatment plant, in the north of Iran. The influent was classified as low strength slowly biodegradable wastewater. The average soluble chemical oxygen demand (SCOD) and biochemical oxygen demand (BOD) of the influent were about 1,130 and 320 mg/L, respectively. Results show that the start-up was accomplished in 90 days in which the ABR reached its maximum SCOD removal of 60%. This was achieved at the controlled mesophilic temperature (37 °C) and optimum hydraulic retention time (HRT) of 24 hours. In spite of the influent characteristics, the performance of ABR has not been inhibited and mostly influenced by HRT. The gradual hydrolysis and acidogenesis were observed within the ABR. The majority of chemical oxygen demand (COD) removal takes place in the first chamber. In addition, the concentrations of readily biodegradable organics (BOD to COD ratio) have been increased and doubled through the reactor. Moreover, the total values of pH, volatile fatty acids and alkalinity remained constant. Consequently, this system can be approved for application as a pretreatment unit for paper mill industrial wastewater treatment plants.

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 porous metallic iron/carbon (Fe0/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 Fe0 was generated in situ by reducing the magnetite at 1,200 °C. Scanning electron microscopy with energy-dispersive X-ray spectroscopy indicated that Fe0 particles, with a size of

Cationic paper was prepared by reaction of paper with 2,3-epoxypropyltrimethylammonium chloride in aqueous suspension, and tested as low-cost adsorbent for wastewater treatment. The experimental results revealed that anionic dyes (Acid Orange 7, Acid Red 18, and Acid Blue 92) were adsorbed on the cationic paper nicely. The maximum amount of dye Acid Orange 7 adsorbed on cationic paper was 337.2 mg/g in experimental conditions. The effects of initial dye concentration, temperature, and initial pH of dye solution on adsorption capacity of cationic paper were studied. The pseudo-first-order and pseudo-second-order kinetic models were applied to describe the kinetic data. The Freundlich and Langmuir adsorption models were used to describe adsorption equilibrium. The thermodynamic data indicated that the adsorption process of dye on cationic paper occurred spontaneously.

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.

This paper presents the design and operational performance data of an anaerobic/aerobic hybrid side-stream Membrane Bioreactor (MBR) process for treating paper mill effluent operated over a 6 month period. The paper mill effluent stream was characterized by a chemical oxygen demand (COD) range of between 1,600 and 4,400 mg/L and an average BOD of 2,400 mg/L. Despite large fluctuations in COD feed concentration, stable process performance was achieved. The anaerobic Expanded Granular Sludge Bed (EGSB) pre-treatment step effectively lowered the organic loading by 65 to 85%, thus lowering the MBR COD feed concentration to consistently below 750 mg/L. The overall MBR COD removal was consistent at an average of 96%, regardless of the effluent COD or changes in the hydraulic retention time (HRT) and organic loading rate (OLR). Combining a high-rate anaerobic pre-treatment EGSB with a Modified Ludzack–Ettinger (MLE) MBR process configuration produced a high quality permeate. Preliminary NF and RO results indicated an overall COD removal of around 97 and 98%, respectively.

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.

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 effluent of the Tasman pulp and paper mill (Kawerau, New Zealand) has been intensively studied for its effects on the health of fishes between 1998 and present. This review summarizes peer-reviewed scientific literature on the reproductive effects of the Tasman Mill effluent on fishes. In the 1990s there was an emerging body of literature from around the world showing that exposure to pulp and paper effluent could cause subtle reproductive alterations in exposed fishes. Locally, the Tarawera River had proved to be a difficult environment to conduct field studies. To overcome some of the difficulties with studying fish populations in the Tarawera River, initial studies on the reproductive health of fishes were focused on mesocosm and laboratory bioassays. During the later part of this period of study, wild fish population sampling was conducted inriver to assess the cumulative impact of multiple discharges. The initial mesocosm studies were conducted with rainbow trout exposures over an entire reproductive development cycle. The Tasman Mill effluent was initially observed to cause reductions in gonad size in females corresponding with lower circulating sex steroid hormones and reduced egg and larval sizes. This result was not observed again in the two subsequent long-term exposures conducted after 2001. Laboratory studies initially found the effluent to have a masculinizing effect on female mosquitofish (Gambusia affinis). This mosquitofish masculinization response disappeared after 2001 and was also not seen in effluent-exposed wild populations. Upstream and downstream populations of the native common bully (Gobiomorphus cotidianus) showed different reproductive timing, and investigation revealed that genetic differences were a potential reason for these differences. Subsequent investigation compared the Tarawera River bully to genetically similar Rangitiki River bully and found no evidence of reproductive alterations. The entire body of published data was assessed with regards to changes at the mill and chemical profiles of the effluent. It was evident that continuing effort on the part of the mill has resulted in gradual improvement in effluent quality over the duration of the studies. However, the disappearance of reproductive effects as assessed by multiple bioassays corresponds to one major change: screen room closure in the pulp mill. This change would have resulted in wood extractives being shunted from the treatment system to the recovery boiler, resulting in a net reduction in compounds derived from wood.

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.

At present, there are many methods for Cr(VI) concentration determination in diluted samples, however, these methods have their own inherent drawbacks, such as long response time, complicated pretreatment, expensive equipment etc. In this paper, a paper-based test strip method specific for determination of diluted Cr(VI) samples was developed. In this method, Aliquat 336, as an anion exchanger was loaded into filter paper to form a test strip. This test strip was used to pre-concentrate Cr(VI) when contacting with the diluted Cr(VI)-containing solution. The Cr(VI)-containing test strip was then immersed into a diphenylcarbazide (DPC) solution (a color forming solution), and the color intensity was correlated to the Cr(VI) concentration. The detection range of the present method was found to be 0.02–1.50 mg/L. The results also showed that the method gave a high selectivity for Cr(VI) in the diluted samples to be tested. The method was applied to synthesized samples and the results, which were compared to those from a reference method, showed that the developed method is an effective, reliable way for Cr(VI) determination in diluted samples.

The use of constructed wetlands (CW) to treat domestic as well as industrial wastewater is rapidly emerging as a viable alternative in India. Constructed wetland systems offer several potential advantages as a wastewater treatment process. These advantages include simple operation and maintenance and lower construction and operating costs. The study evaluated the effectiveness of the subsurface flow constructed wetland for pulp and paper mill wastewater treatment and also the effectiveness of plant species. A pilot scale study was conducted to examine the feasibility of a CW system for treatment of pulp and paper mill wastewater during summers as well as winters at different hydraulic retention time (HRT) such as 1.5 days, 3.5 days and 6.5 days. Wetland beds were prepared with easily available plants such as Typha angustifolia and Canna indica. Specific performance objectives were to decrease biochemical oxygen demand (BOD), chemical oxygen demand (COD), total solids (TS) and color. Comparison of mean inlet and outlet concentrations showed that the CW system could effectively reduce the output of TS (87.6 ± 1.1%), COD (86.6 ± 2.0%), BOD5 (80.01 ± 0.1%), color (89.4 ± 0.6%) during summer and TS (72.15 ± 0.71%), COD (70.94 ± 2.3%), BOD5 (72.07 ± 2.2%) and color (74.90 ± 0.47%) during winter at 3.5 days HRT.

Pulp and paper mill effluents (PPMEs) may contain high levels of otherwise naturally occurring organic pollutants such as plant sterols, which are suspected endocrine disrupting chemicals. Exposure to such chemicals may cause various physiological and morphological abnormalities that have been reported in the fish and other aquatic life inhabiting PPME receiving waters. Plant sterols, or phytosterols, form a constituent of wood extractives that may be released into the effluents during the pulping and paper making processes. Isolation and analysis of sterols from the complex mixture of PPMEs is challenging and standard analytical protocols do not exist. The need for having a reliable method for analyzing a particular environmental contaminant such as plant sterols cannot be overemphasized. In the present study a technique was modified for reliable analysis of PPME sterols. The technique involves liquid-liquid extractions using methyl-t-butyl ether and trimethyl-silylation derivatizations of the extracted sterols. Identification and quantification of the PPME sterols were accomplished by gas chromatography and mass spectrometry. Analytical problems were resolved by conducting multiple extractions, drying the sterol extracts, and redissolving and silylating the extracts at an increased derivatization temperature of 70°C. This shortened the suggested incubation period from 12 to 4 h. The modified technique offered improved method sensitivity and reproducibility, and successfully quantified campesterol, β-sitosterol, β-sitostanol, stigmasterol, stigmastanol, cholesterol, and ergosterol in PPMEs. Primary and secondary treated PPMEs analyses suggested 800 ± 190 µg/L total sterols in primary effluents, and 211 ± 90 µg/L in biologically treated final effluents. β-Sitosterol, β-sitostanol, and campesterol alone accounted for about 80% of the total sterols. A general comparison of the sterols in primary and secondary effluents suggested about 73% removal across the secondary treatment systems sampled.