Treatment Of Pulp Mill Wastewater Research Articles

Development and application of a quasi-static Langmuir isotherm for modelling selected resin acid fate in pulp mill wastewater treatment

Resin acids are pulp mill effluent contaminants that exhibit significant solubility, diffusivity, and surfactancy changes with pH within the range typically used for biological treatment. Such physical–chemical property changes which can influence removal during biological wastewater treatment, can be characterized by dynamic surface tension measurements. Dynamic surface tension measurements were made by the maximum bubble pressure method during batch treatment of selected resin acids in pulp mill effluent. Interpretation of dynamic surface tension data was made through the framework of a quasi-static Langmuir isotherm model that was derived as part of this investigation. The results suggested that under acidic conditions, resin acids form associations with other dissolved organic matter contained in pulp mill effluent, while under alkaline conditions, they behave as relatively soluble surfactants. A resin acid residuum, or threshold concentration, has been found to increase under acidic growth conditions. This residuum increase corresponded to an inferred reduction in resin acid bioavailability that was suggested from the isotherm modelling. The development of quasi-static isotherm adsorption models has application in computer simulation for design of adsorption based unit processes, and could potentially be utilized as an informative treatment process monitor.

Treatment of pulp mill and oil sands industrial wastewaters by the partial spray freezing process

The spray freezing process, a natural freezing technology, was used to treat pulp mill effluent and oil sands tailings pond water. The wastewaters froze partially or completely (i.e. with or without runoff generation) during the spraying operation. Greater than 60% impurity reduction in the spray ice was obtained when 30% of the total volume of the sprayed water was released as runoff. Organic and inorganic contaminants were rejected with different efficiencies. The impurities were uniformly distributed within the ice columns when the spray ice was produced without generating any runoff. While a significant increase in impurity concentration was observed at the bottom of the ice formed with runoff production. The spray freezing process is an effective and economically feasible technique for wastewater treatment in cold regions. To achieve higher impurity removal efficiency, the wastewater should be only partially frozen during spray ice production.

An Assessment of Variability of Pulp Mill Wastewater Treatment System Bacterial Communities using Molecular Methods

Abstract The DNA fingerprinting techniques, 16S-restriction fragment length polymorphism (16S-RFLP), ribosomal intergenic spacer analysis (RISA) and repetitive extragenic palindrome PCR (Rep-PCR), were used for analyzing the bacterial communities of seven pulp and paper wastewater treatment systems. All three methods generate DNA fingerprints that can be compared using the computer-assisted program, Gelcompar©. Community similarity coefficients were based on quantitative determinations of both the positions of the DNA bands and the band intensities in order to compare the relative differences in the populations. Unique 16S-RFLP DNA fingerprints were observed for each mill suggesting that individual mills contained phylogenetically different communities. However this method was not sensitive enough to detect differences within a mill treatment system from different locations or from different sampling times. The RISA method, which generated more complex fingerprints than 16S-RFLP, could, for some mills, discern differences between samples. The Rep-PCR technique, however, showed the highest degree of resolution and produced not only distinct patterns for each mill but also distinct fingerprints for the temporal and spatial samples from some of the treatment systems. The sensitivity of this method might potentially be used to monitor the stability of the bacterial community within a secondary treatment system.

An Ecological Risk Assessment of Nonylphenol and Its Ethoxylates in the Aquatic Environment

Nonylphenol ethoxylates (NPEs) are a group of surfactants that are widely used for industrial, commercial, institutional and household purposes in Canada. Ethoxylation of nonylphenol (NP) occurs upon reaction with ethylene oxide, producing NPEs, although NP is also used in the production of the antioxidant tris(nonylphenol)phosphite. NP and NPEs are not produced naturally, and the primary route of environmental exposure to NP and NPEs is via textile mill, pulp and paper mill and municipal wastewater treatment plant effluents. NPEs occur as complex mixtures and are described by the average ethoxylate chain length, which ranges from 1 to 100. The environmental fate of NPEs is strongly dependent on the effluent and, the degree and type of treatment to which the effluent is subjected. An ecological risk assessment was performed to determine if exposure to NP and NPEs results in effects on the Canadian environment, based on current use patterns. The Canadian ecological risk assessment found that adverse effects on aquatic organisms are likely, although assumptions were made with respect to appropriate dilution factors.

Characterization of two novel yeast strains used in mediated biosensors for wastewater.

After isolation from a pulp mill wastewater treatment facility, two yeast strains, designated SPT1 and SPT2, were characterized and used in the development of mediated biochemical oxygen demand (BOD) biosensors for wastewater. 18S rRNA gene sequence analysis revealed a one nucleotide difference between the sequence of SPT1 and those of Candida sojae and Candida viswanthii. While SPT2 had the highest overall homology to Pichia norvegensis, at only 73.5%, it is clearly an ascomycete, based on BLAST comparisons and phylogenetic analyses. Neighbor-joining dendrograms indicated that SPT1 clustered with several Candida spp., and that SPT2 clustered with Starmera spp., albeit as a very deep branch. Physiological tests, microscopic observations, and fatty acid analysis confirmed that SPT1 and SPT2 are novel yeast strains. Physiological tests also indicated that both strains had potential for use in mediated biosensors for estimation of BOD in wastewater. The lower detection limits of SPT1- and SPT2-based K3Fe(CN)6-mediated biosensors for a pulp-mill effluent were 2 and 1 mg BOD/L, respectively. Biosensor-response times for effluents from eight different pulp mills were in the range of 5 min. Reliability and sensitivity of the SPT1- and SPT2-based biosensors were good, but varied with the wastewater.

Batch and continuous studies on treatment of pulp mill wastewater by Aeromonas formicans

Batch and continuous studies have been conducted on the treatment of black liquor from a kraft pulp and paper mill by a bacterial strain, Aeromonas formicans. The results of batch studies revealed that the strain was able to remove 71% and 78% of COD and lignin respectively, while the colour removal efficiency was around 86% in 10 days of retention time. The analysis of lignin degradation products by gas chromatography after 20 days of incubation revealed the formation of some phenolic acids, which were responsible for the decrease in pH during batch studies. The removal efficiencies of COD, colour and lignin obtained in continuous reactor studies were 73, 88 and 77% respectively for an 8 day detention period and these efficiencies were almost the same as obtained in batch studies. © 2001 Society of Chemical Industry

Batch and continuous studies on treatment of pulp mill wastewater by Aeromonas formicans

AbstractBatch and continuous studies have been conducted on the treatment of black liquor from a kraft pulp and paper mill by a bacterial strain, Aeromonas formicans. The results of batch studies revealed that the strain was able to remove 71% and 78% of COD and lignin respectively, while the colour removal efficiency was around 86% in 10 days of retention time. The analysis of lignin degradation products by gas chromatography after 20 days of incubation revealed the formation of some phenolic acids, which were responsible for the decrease in pH during batch studies. The removal efficiencies of COD, colour and lignin obtained in continuous reactor studies were 73, 88 and 77% respectively for an 8 day detention period and these efficiencies were almost the same as obtained in batch studies.© 2001 Society of Chemical Industry

Biodegradation of Dibenzofuran and Dioxins by Pseudomonas Aeruginosa and Xanthomonas Maltophilia

This study was aimed at finding microorganisms capable of biodegrading dioxins efficiently to develop a biotechnological treatment for decomposition of dioxins. Dibenzofuran (DBF) was used as a test substance to cultivate and to screen microbes active in degrading dioxins. Two microbial species (Pseudomonas aeruginosa and Xanthomonas maltophilia) which could degrade DBF were isolated from the sludge of a Kraft pulp mill wastewater treatment plant. The optimal conditions for biodegrading DBF were 30 and pH 7. Ps. aeruginosa, which had a high growth rate with DBF as carbon source showed high growth rates in the presence of such dioxins as dibenzo-p-dioxin, medium growth with 1-chlorodibenzo-p-dioxin, 2-chlorodibenzo-p-dioxin and 2,8-dichlorodibenzofuran, low growth with 2,6-dichlorodibenzo-p-dioxin and 1,2,3,4-tetrachlorodibenzo-p-dioxin and no growth with octachlorodibenzofuran. These results suggested that the growth rate of Ps. aeruginosa using dioxins as carbon source decreased with the increase in the degree of chlorine substitution. Activity of Ps. aeruginosa biodegrading dioxins was high for DBF, dibenzo-p-dioxin and 1-chlorodibenzo-p-dioxin and low for 2,8-dichlorodibenzofuran, 3,6-dichlorodibenzofuran, 2-chlorodibenzo-p-dioxin and 2,6-dichlorodibenzo-p-dioxin. These results suggested that there is a correlation between growth and the ability to biodegrade dioxins. On the other hand, the efficiency in the biodegradation of 1,2,3,4-tetrachlorodibenzo-p-dioxin was comparatively high although the growth rate on this dioxin was low. Hydroxydibenzofuran, 2-hydroxy-3-allyl-benzofuran and 2-carboxyvinyloxy phenyl acetic acid were identified by gas chromatograph-mass spectrometry (GC/MS) as products of DBF biodegradation by Ps. aeruginosa, suggesting a possible biodegradation pathway for dioxins.

On-line enzyme activity determination using the stopped-flow technique: application to laccase activity in pulp mill waste-water treatment

An automated system for on-line measurement of enzyme activity is proposed. The system uses a flow injection manifold in the stopped-flow mode to measure initial reaction rates. The time during which the flow is halted is selected in such a way as to optimise the enzyme/substrate ratio for the correct determination of activity values. The proposed system was used to determine the activity of laccase produced by the fungus Trametes versicolor immobilised on nylon in a fixed-bed reactor used for treating pulp mill waste water.

Evaluation of dioxin mobility and spoils leaching in a surface coal mine reclaimed with bleached kraft pulp and paper mill biosolids

A surface coal mine in southeastern Ohio has been reclaimed with approximately 15 to 25 cm thickness of biosolids from a bleached kraft pulp and paper mill wastewater treatment plant. Soil, vegetation, rodents, earthworms, insects, fish, frogs, sediment, and algae samples were collected and analyzed for 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran. Water samples from lakes receiving drainage from unreclaimed and biosolids reclaimed areas were collected and analyzed for various parameters, including pH and metals. The trace levels of dioxin and furan in the pulp and paper mill biosolids did not bioaccumulate in rodents, insects, or earthworms or translocate into plants living in the reclaimed area. The trace levels of dioxin and furan in biosolids did not sufficiently migrate to a drainage lake to result in significant concentrations in fish, frogs, algae, or vegetation. The biosolids reclamation resulted in dramatic decreases in spoils leaching of acid, aluminum, calcium, iron, magnesium, manganese, nickel, and zinc. This work supports the thesis that surface mine reclamation with pulp and paper mill biosolids is safe and effective.

Wetland Treatment of Pulp Mill Wastewater

Ten wetland ponds, each 1430 m2 (1/3 acre) in area are being utilized to evaluate the treatment of wastewater from a pulp mill. The ponds are being operated at a depth of 46 cm (18″) and detention times are 2 and 10 days. Six of the ponds have been planted to cattails (Typha latifolia) and three to bulrush (Scirpus acutus). One of the ponds is filled with large (150 mm) stone to compare a subsurface non-plant system. In 24 stock tanks, 8 aquatic plant species (Cattail, Hardstem Bulrush, Bolander's Rush, Common Spike Rush, Water Mannagrass, Beaked Sedge, Water Parsley and Yellow Pond Lily) are being grown to evaluate the effect of plants in the wetland treatment of wastewater. These same species are being evaluated in a larger area for competitiveness and hardiness in the wastewater. The ponds were planted in the winter of 1990/91. Results of this work on treatment of biochemical oxygen demand, solids and colour removal will be reported. Removals are in the range of 55%, 70% and less than 5% for the three parameters, respectively.

VOC Fate Model Verification at Multiple Pulp Mill Wastewater Treatment Sites

A model of organic compound removal by biological wastewater treatment processes receiving pulp and paper industry wastewaters has been developed and initial model verification performed at a single mill site. This paper presents the results of further model verification conducted at multiple mill sites, including replication of the original site. In addition, VOC losses at other unit processes are quantified. Activated sludge basin chloroform volatilization rates are predicted to within twelve percent of the measured rates. Predicted overall methanol removals are consistent with observed removals although difficulties encountered during off-gas sampling preclude determination of the extent of removal due to volatilization.

Nitrogen and Phosphorus Limits for Nutrient Deficient Industrial Wastewaters

For biological treatment of nutrient deficient industrial wastewaters, such as those of the pulp and paper industry, the addition of nitrogen and phosphorus is essential. As a certain surplus is necessary, both elements will be found in the effluent in varying concentrations. For the often used activated sludge treatment 5 parts of N and 1 part of P are said to be required for elimination of 100 parts of BOD. In-plant optimization generally leads to about 3.5 parts of N and 0.6 parts of P for 100 parts of BOD. In most plants N is added as urea and P as phosphoric acid. Optimized nutrient dosage aimed at stable operating conditions in the treatment plant generally gives average concentrations of 1 mg/l of both ammonia N and phosphate P in the treated effluent. However, due to fluctuations in loading and efficiency, variation coefficients of more than 100 % result in maximum concentrations in 24 hours mixed samples of more than 10 mg/l for N and P. Three examples of operational results are evaluated and discussed in detail. Water quality requirements will impose general limitations on N and P concentrations in treated effluents. Depending on the concentration limits and on the type of limited substance - i.e. ammonia N, total inorganic N or total N, phosphate P or total P - different strategies have to be developed. Nutrient dosage depending on the wastewater amount will become state of the art in the near future. The next step would be a loading dependent dosage. No results of technical operation are known which show the effluent concentrations obtainable with this technique. For cases in which limits cannot be met with this strategy the possibilities of nitrification, denitrification and biological P removal are discussed for nutrient deficient wastewaters. Results show that nitrification will work at low ammonia concentrations, however no steady nitrification will be obtained. Denitrification, on the other hand, seems to be difficult with low nitrate concentrations. At the present stage, no technical process meeting stringent total N or total inorganic N limits is known to exist for this type of effluent. Low P concentrations in the effluent can only be achieved by tertiary treatment, preferably final flocculation filtration processes. However, these will give rise to special problems in the treatment of pulp mill wastewaters, which are discussed in the paper.

Anaerobic treatment of pulp and paper mill wastewaters

AbstractSecondary treatment of pulp and paper mill wastewaters for biochemical oxygen demand (BOD) removal worldwide has traditionally been accomplished, and particularly in North America, by aerobic treatment processes, including aerated stabilization basin and activated sludge. In recent years, however, interest in applying anaerobic processes to treat pulp and paper mill effluents has increased, with at least 25 full‐scale installations currently operating or under construction.

Sulfur Reduction and Inhibition in Anaerobic Treatment of Simulated Pulp Mill Wastewater

Summary Bioassay studies were conducted on the anaerobic degradation of a simulated pulping wastewater (evaporator condensate) containing sulfur compouds (sulfate, sulfite, or dithionite). Sulfite and dithionite (1000 mg S/l) totally inhibited methane production while sulfate (1000 mg S/l) had a minor effect. High concentrations of sulfite (1000 mg S/l) appeared to inhibit sulfite reduction. Biochemical reduction of dithionite (100–1000 mg S/l) could not be demonstrated. Methane bacteria outcompeted sulfate-reducing bacteria when methanol was the only substrate available. Methanol was utilized by sulfate reducers in the presence of a specific methanogen inhibitor, BES. Increase of the methanol concentration in an acetate -methanol medium stimulated sulfate reduction.

Examination of potential risks from exposure to dioxin in paper mill sludge used to reclaim abandoned Appalachian coal mines

The potential human health risks associated with trace concentrations of TCDD equivalents in a pulp and paper mill wastewater treatment plant sludge used in the reclamation of abandoned Appalachian coal mines were assessed. Maximum hypothetical exposures to sludge containing trace concentrations of TCDD equivalents were estimated to result in insignificant health risks.

Control of the Phosphorus Level of Effluent in the Treatment of Forest Industry Waste Waters

Pulp and paper mill wastewaters are nutrient deficient, BOD5:N:P may be as low as 100:1:0.2. Now that purification requirements have been tightened, the activated sludge process seems to be most commonly used treatment method. The conventional activated sludge process requires BOD:P ratios of 100 to 0.6 resulting in a need for P addition and hence in a possible increase in the P-level of the effluent. In Finland and also in some other areas phosphorus removal is of great importance in the prevention of eutrophication of watercourses. There are several methods to control phosphorus level, such as biological phosphorus removal, running of the process under starvation of phosphorus, tertiary (chemical) treatment and simultaneous precipitation of phosphorus. This paper lists possible treatment methods and presents more closely chemical treatment using simultaneous precipitation by ferrous sulphate. The results are based on both pilot and full-scale experiments in two kraft pulp mills. The study showed that phosphorus concentration can be reduced to a level of 1.2 mg/l (tot.P) by adding ferrous sulphate to the aeration basin in activated sludge treatment of kraft pulp mill wastewaters. Ferrous sulphate has, also, a slight positive effect on the sludge properties e.g. sludge settleability.

Activated carbon by pyrolysis of sludge from pulp-mill waste-water treatment.

Feasibility of production of activated carbon from sludge of CGP (chemi-ground pulp) wastewater was studied by means of laboratory-scale experiments. In this work, alum (Al2(SO4)3⋅18H2O) was used as coagulating agent. The main carbonizing and activating agent used was ZnCl2, and K2S was also used for comparison. The quality of carbons obtained was examined with reference to yield, specific surface area, pore volume and pore size distribution. The influence of activation conditions, such as weight ratio of sludge to ZnCl2, activation temperature and drying time, to the development of pore structure is discussed.

A Study of Renovation of Pulp Mill Waste Water

Some adsorption characteristics of kraft pulp lignin on activated carbon from aqueous solution were investigated for the evaluation of the method of pulp mill waste water treatment with activated carbon. The adsorption rate of lignin was very slow. The adsorption capacity was about 2 to 7% by weight in the range of lignin concentration from 1 to 40 ppm, and it increased regularly with increasing of hydrogen ion concentration in the range of pH from 7 to 11. The adsorbed lignin was not desorbed in distilled water. The results of this work show that the further investigations of the adsorption method should be valuable for the clarification and the reuse of pulp mill waste water.