An investigation into the occurrence of sewage fungus in rivers containing papermill effluents—I. Review of previous research

Wastewaters from the manufacture of pulp and paper have given rise to problems of excessive microbial growth in rivers over a number of years. This paper is the first in a series of four articles describing research undertaken by PIRA at four U.K. paper/board mills (one integrated with pulp production) over the period 1978–1980. This first paper briefly reviews the published literature on sewage fungus growth from pulp and paper mill discharges up to 1978, but mainly describes previously unpublished work undertaken by PIRA over the period 1965–1975. This introductory paper thus provides a state-of-the-art review of methods to control sewage fungus growth from pulp and paper mill effluents prior to commencement of the research described in the following three articles.     

An investigation into the occurrence of sewage fungus in rivers containing papermill effluents—II. Chemical analysis of mill effluents

This is the second in a series of four articles describing research undertaken at PIRA during 1978–1980 on the causes and prevention of sewage fungus growth in rivers receiving paper and board mill effluents. This paper describes the sampling and analytical programme at three U.K. paper and board mills, the objective of which was to characterise the dissolved organic matter in final effluents and component wastewater streams. The analyses conducted were dissolved organic carbon (DOC), carbohydrate, glucose, gelatin, melamine, hydrolysed sugars and molecular weight distribution. The results are related to the raw materials and manufacturing processes used at each mill site.     

An investigation into the occurrence of sewage fungus in rivers containing papermill effluents—III. Removal of sewage fungus nutrients

This is the third in a series of four articles describing research undertaken at PIRA during 1978–1980 on the causes and prevention of sewage fungus growth in rivers receiving paper and board mill effluents. This paper describes pilot scale trials carried out at two papermills to assess various treatment systems for removal of BOD and effluents were biological filtration through plastic media, activated sludge, multi-media mechanical filtration and hydrogen peroxide addition. Both biological systems proved effective, but mechanical filtration showed no clear benefit. Hydrogen peroxide addition was able to remove a substantial proportion of the free glucose concentration, but verification of the direct effect on sewage fungus growth was impeded by the poor sewage fungus growth generated by the untreated clarified effluent at this time.     

An evaluation of the potential toxicity of treated bleached kraft mill effluent to striped bass (Morone saxatilis walbaum) larvae exposed through metamorphosis to the juvenile stage

Twenty-day-old striped bass (Morone saxatilis) larvae were exposed to a range of treated bleached kraft mill effluent (BKME) concentrations from 0 to 20% effluent by volume (v/v) under continuous flow test conditins. The experimental test concentrations in the 2–20% BKME test aquaria had a BOD₅ which ranged from < 1 to 5 mg l⁻¹, TSS 12–17 mg l⁻¹, and true color 35–416 mg l⁻¹. Bleached kraft mill effluent did not kill larvae exposed to it for 20 days through metamorphosis to the juvenile stage. The BKME did not alter growth in length, weight or condition factor in larvae over the 20-day exposure period as determined by multiple regression analysis. A linear regression analysis on the dry weight data at Day 20 only, however, indicated a trend of decreasing weight with increasing BKME concentration. Effluent-exposed larvae also developed normally during the 20-day study. All individuals examined completed the transformation from postlarvae to juveniles by the age of 40 days.     

Removal of indigenous rotaviruses during primary settling and activated-sludge treatment of raw sewage

An eight month study of indigenous rotavirus removal during primary settling and activated sludge treatment of raw sewage was made in a plant in Houston, Texas treating 1.5 million gal day⁻¹. An average reduction of 44–55% was obtained by primary settling and a 93–99% reduction was achieved in final chlorinated effluents. Composite sampling at 1 h intervals over a 24 h period indicated average removals of 85% compared to a misleading 6% indicated by one set of grab samples of raw sewage and effluent collected simultaneously. Quantification of rotaviruses was made by immunofluorescent foci counts 24 h after addition of sample concentrates to coverslip cultures of fetal rhesus kidney cells. Rotaviruses varied from 40–5101⁻¹ of raw sewage and from 0 to 25 in the final chlorinated effluent.     

Sewage fungus growth in rivers receiving paper mill effluent

A study has been made of the chemical composition of a paper mill effluent which is known to cause severe growths of sewage fungus in the river into which it is discharged. Carbohydrate proved to be the major soluble organic component and was investigated in detail, so that the raw materials and mill processes which were responsible for its presence could be determined. An investigation into the amount and type of carbohydrate which was extracted during the aqueous disintegration of waste paper and chemically produced wood pulp (the two major raw materials) revealed that the former made the greater contribution to the dissolved carbohydrate which was present in the effluent.In an attempt to determine the availability of this carbohydrate as a nutrient for ‘sewage fungus’, a pure culture of Sphaerotilus (the dominant bacterium), which had been isolated from the river below the effluent discharge, was maintained and used for batch culture experiments. Measurements were made of the rate and extent of assimilation of various substrates which had been shown to be or were likely to be present in the effluent. Glucose, maltose, soluble oxidized starch and effluent carbohydrate have all been shown to be suitable nutrients.     

Effects of lignin and chlorolignin in pulp mill effluents on the binding and bioavailability of hydrophobic organic pollutants

The partition coefficients (K_p) of benzo(a)pyrene (BaP), 3,3′,4,4′-tetrachlorobiphenyl (TCB) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) to dissolved kraft lignin (Indulin AT), chlorolignin isolated from a bleached kraft mill effluent (BKME) and dissolved organic matter (DOM) in a lake receiving BKME were measured by equilibrium dialysis. The K_p values of kraft lignin were 28.2 × 10⁵, 6.5 × 10⁵ and 15.9 × 10⁵ and those of chlorolignin were 8.3 × 10⁵, 2.9 × 10⁵ and 2.2 × 10⁵ for BaP, TCB and TCDD, respectively. In addition, DOM in a series of lake water samples collected from the southern part of Lake Saimaa, SE Finland, receiving BKME revealed higher binding capacities to all of the three model compounds than natural DOM in water upstream from the pulp mill. An important phenomenon related to the environmental transport and fate of xenobiotics was almost the full reversibility of the binding between chlorolignin and model compounds. The obtained K_p values of chlorolignin after a 4 day dissociation period were 12.6 × 10⁵ and 4.6 × 10⁵ for BaP and TCDD, respectively.In short-term (24 h) accumulation experiments with Daphnia magna the effects of kraft lignin and chlorolignin on the bioavailability of three model compounds was very clear. The bioconcentration factors of the xenobiotics in the chlorolignin containing water (DOC = 10 mg C/l) were 20–30 and 25–35% of those organic-free control and upstream reference waters (DOC = 7.2 mg C/l), respectively. The effect of chlorolignin of BKME on the bioavailability of model compounds was also seen in the lake water series of Lake Saimaa.     

Effect of pH on toxicity of kraft pulp and paper mill effluent to salmonid fish in fresh and seawater

In freshwater bioassays with juvenile rainbow trout (Salmo gairdneri), at initial pH values from 4 to 11, kraft mill effluents were considerably less toxic at pH 9–10 than at neutrality. When pH of test solutions was controlled throughout the bioassay period, the least toxic range was 8.5–9.5. Toxicity at typical receiving-water pH values was 50–67% greater.The acute toxicity of effluent samples to yearling coho salmon (Oncorhynchus kisutch) was identical for these effluents in seawater and freshwater respectively, provided that the pH was adjusted and held at the same value, and that test fish were previously acclimated to the dilution water for several months. Thus seawater constituents other than pH did not affect the acute toxicity of pulp and paper mill effluents appreciably.     

The growth of cladophora glomerata in a river receiving sewage effluent

A considerable improvement in the natural flora of the River Great Stour has occurred since the mid-1960s when dense growths of Cladophora glomerata dominated sections of the river with the disappearance of some rooted macrophytes. Cladophora growths in the river in response to changing river conditions and sewage treatment operations during a thirty year period are reviewed. A vegetation mapping programme undertaken from 1978 to 1982 to assess the influence of a sewage treatment works discharge on the growth of the filamentous alga has shown that previous recommendations to reduce dissolved phosphorus concentrations in the final effluent need not be implemented.     

Fate of wood extractives in wastewater treatment plants at kraft pulp mills and mechanical pulp mills

Extensive environmental effects of the forest industry led to implementation of activated sludge treatment of effluents in the 1980s. Although the existence of chlorinated compounds in the effluents has decreased, a discussion about the possible environmental effects of elemental-chlorine-free (ECF) and total-chlorine-free (TCF) bleached pulp mill effluents has arisen, and chronic effects on aquatic organisms have still been found. Recently, studies have mainly focussed on wood extractives and their role in the effects of effluents. Resin acids and unsaturated fatty acids are found to be toxic, and plant sterols are reported to have adverse endocrine effects on water organisms already at low concentrations. In this study, Finnish wastewater treatment plants of an ECF kraft pulp mill, a paper mill, and an integrated TCF kraft pulp and paper mill were sampled in order to ascertain how wastewater treatment plants, and especially activated sludge treatments, remove wood extractives. Concentrations of extractives in discharged wastewaters varied between 0.4 and 11 g/t kraft or mechanical pulp, and the concentrations decreased over 95% during the treatment processes. Of the wood extractives, 1.1-64% were adsorbed to biosludge and 35-99% were degraded or transformed to other forms during the activated sludge treatment. A major part of these compounds were discharged in particles (74-99%). The removal of extractives was efficient even in the effluent treatment plant, which was highly loaded during the sampling period.     

Biological treatment of the effluent from a bleached kraft pulp mill using basidiomycete and zygomycete fungi

Three white-rot fungi (Pleurotus sajor caju, Trametes versicolor and Phanerochaete chrysosporium) and one soft-rot fungi (Rhizopus oryzae) species confirmed their potential for future applications in the biological treatment of effluents derived from the secondary treatment of a bleached kraft pulp mill processing Eucalyptus globulus. Among the four species P. sajor caju and R. oryzae were the most effective in the biodegradation of organic compounds present in the effluent, being responsible for the reduction of relative absorbance (25-46% at 250 nm and 72-74% at 465 nm) and of chemical oxygen demand levels (74 to 81%) after 10 days of incubation. Laccase (Lac), lignin (Lip) and manganese peroxidases (MnP) expression varied among fungal species, where Lac and LiP activities were correlated with the degradation of organic compounds in the effluent treated with P. sajor caju. The first two axes of a principal component analysis explained 88.9% of the total variation among sub-samples treated with the four fungus species, after different incubation periods. All the variables measured contributed positively to the first component except for the MnP enzyme activity which was the only variable contributing negatively to the first component. Absorbances at 465 nm, LiP and Lac enzyme activities were the variables with more weight on the second component. P. sajor caju revealed to be the only species able to perform the biological treatment without promoting an increment in the toxicity of the effluent to the Vibrio fischeri, as it was assessed by the Microtox® assay. The opposite was recorded for the treatments with the other three species of fungus. EC_50-5 min values ranging between 28 and 57% (effluent concentrations) were recorded even after 10 to 13 days of treatment with P. chrysosporium, R. oryzae or with T. versicolor.     

Use of rat brain Na, K-ATPase assay to determine effectiveness of biological treatment to reduce toxicity of paper mill effluents

This work evaluates the toxicity of kraft mill wastewaters and the extent of detoxification attained after biological treatment of these effluents with the fungus Phanerochaete chrysosporium. The degree of inhibition of the enzyme Na⁺, K⁺-ATPase was used as an indicator of toxicity. The untreated alkali extraction stage effluent significantly inhibited the enzyme activity. When this effluent was treated biologically the degree of enzyme inhibition was practically reduced to zero. The inhibition of the enzyme Na⁺, K⁺-ATPase was found to be a suitable indicator of toxicity for bleached pulp and paper mill waste waters.     

Some effects of pulp and paper wastewater on microbiological water quality of a river

A study was conducted to detect the source of fecal indicator bacteria and measure the resulting impairment of water quality of the Sturgeon River at Sturgeon Falls, Ontario, Canada. The bacteriological water quality of the river above the dam at Sturgeon Falls was fairly good, while below the dam the water quality was degraded. The principal input of fecal indicator bacteria was traced to the paper mill at Sturgeon Falls. The impairment of water quality was detected all the way to recreational areas near the mouth of the river. The impaired stretch of the river had diminished aesthetic appeal. Other sources of indicator bacteria could be masked by the large numbers of similar bacteria discharged from the paper mill. The principal fecal coliform was Klebsiella pneumoniae. In pulp mill wastes the fecal origin of this bacterium can be disputed, and so its presence in large numbers interfered with the interpretation of fecal coliform results. K. pneumoniae is also an opportunistic pathogen which causes infections in humans. Thermotolerant oxidase positive bacteria which were isolated from the paper mill wastes, register as false positives in the fecal coliform test causing problems in interpretation. Pseudomonas aeruginosa was detected in the pulp mill wastewater, and at a level of 82 PA 100 ml⁻¹ in recreational areas of the river. This was considered to be of some hazard to users of the water. In addition, Escherichia coli was detected in the mill wastewater, at about 200 EC 100 ml⁻¹, and this probably indicated some measure of fecal pollution though likely of animal origin. Finally the nutrient rich wastewater led to an approx. 50-fold increase in density of aerobic heterotrophic bacteria in the river water, as well as the production of a slimy filamentous growth on surfaces, stones and wooden pilings, in the river. The principal organism in this slime was the fungus Leptomitus.     

The ecology of "fecal indicator" bacteria commonly found in pulp and paper mill water systems

Coliform bacteria have long been used to indicate fecal contamination of water and thus a health hazard. In this study, the in-mill water and external effluent treatment systems of seven typical Canadian pulp and paper mills were all shown to support the growth of numerous coliforms, especially Klebsiella Spp., Escherichia coli. Enterobacter spp., and Citrobacter spp. In all mills and most sampled locations, klebsiellas were the predominant coliforms. Although all but one of the mills had no sewage input and most disinfected their feed (input) water, all contained the most typical fecal indicator bacterium, E. coli. Many of the mill coliforms were classified as fecal coliforms by standard "MPN" and metabolic tests, but this was shown to be due to their thermotolerance, not their origin. Mill coliforms were shown not to be just simple transients from feedwater or furnish (wood), but to be continuously growing, especially in some of the primary clarifiers. Isolated mill coliforms grew very well on a sterilized raw combined mill effluent. The fecal streptococci (enterococci), alternative indicators of fecal health hazards, were common in all mills in the absence of sewage. Ten strains of E. coli isolated from four mills were all shown to be non-toxigenic strains of harmless serotypes. No salmonellas were found. Therefore, the use of total coliform, fecal coliform, enterococci, or E. coli counts as indicators of fecal contamination, and thus of health hazard in pulp and paper mill effluents or biosolids (sludges) known to be free of fecal input is invalid.     

Responses of phytoplankton to renewed solar radiation in a stratified inlet

The hypothesis that humic stain discharge by a pulp mill sited at the head of Alberni Inlet was responsible for an oxygen deficiency by blocking sub-halocline photosynthesis was tested by two experimental methods. In the short term (4–5 h) no production could be demonstrated using the ¹⁴C method and exposing sub-halocline water to light. In the longer term an intense phytoplankton bloom occurred after a 3-day lag period. It was concluded that removal of humic stain from the pulpmill effluent will result in renewed oxygen production below the halocline.     

Sedimentary coprostanol and hydrocarbon distribution adjacent to a sewage outfall

The concentrations of coprostanol and hydrocarbons were measured in the effluent from the Chesapeake-Elizabeth sewage treatment plant (STP) and surface sediments from the area surrounding the effluent discharge site. Most of the coprostanol (> 84%) and hydrocarbons (> 91%) were associated with particulates in the effluent. The area was found to be dynamic where changes in the percentage and distribution of fine grained sediments occur over periods of months and the movement of these sediments is an important determinant of the distribution of sewage derived contaminants. The Chesapeake-Elizabeth STP was found to be responsible for only 7% of the hydrocarbon contamination of the sediments in the study area. The sediment hydrocarbon distribution also indicates that the Bay Bridge tunnel may be a unique source of hydrocarbons to the lower Chesapeake Bay. This study shows the usefulness of coprostanol in providing a better understanding of the fate and importance of sewage derived contaminants in areas around sewage outfalls.     

The effectiveness of a biological treatment with Rhizopus oryzae and of a photo-Fenton oxidation in the mitigation of toxicity of a bleached kraft pulp mill effluent

Huge efforts have been made both in adopting more environmental-friendly bleaching processes, and in developing advanced oxidation processes and more effective biological treatments for the reduction of deleterious impacts of paper mill effluents. Even so, the success of such treatments is frequently reported in terms of chemical parameters without a proper evaluation of the effluent's toxicity mitigation. This is the first study reporting an exhaustive evaluation of the toxicity of a secondary bleached kraft pulp mill effluent, after either tertiary treatment with the soft-rot fungi Rhizopus oryzae or with a photo-Fenton oxidation, using a battery of freshwater species. As it has been reported the photo-Fenton/UV treatment has proved to be the most effective in reducing the colour and the COD (chemical oxygen demand) of the effluent. Nevertheless, extremely low EC₅₀ values were reported for almost all species, after this tertiary treatment. The treatment with R. oryzae was less effective in terms of colour removal and COD reduction, but proved to be the most promising in reducing toxicity.     

The decomposition of sewage sludge in seawater

Laboratory experiments were conducted over a 12 week period to follow the decomposition of sewage sludge in seawater and in sediment-seawater mixtures under aerobic and anaerobic conditions at 4° and 21°C. Results showed that the sewage sludge decomposed more rapidly in the presence of oxygen. Dissolved organic carbon, a major carbon source in sewage sludge, abruptly decreased to very low concentrations in 3–4 weeks in aerobic systems; concentrations of particulate carbon decreased only gradually during the 12 week period. Aerobic conditions at the sewage sludge dump site in the New York Bight apex can promote rapid decomposition of sewage sludge if it is distributed evenly over an area of at least 5.2 km² (2 miles).     

Bioleaching of metals from sewage sludge: Microorganisms and growth kinetics

Microbial leaching is one of the advantageous methods of removing heavy metals from sewage sludge, however, the microbiological aspects of this technology have not been studied. This study presents the characterization of the naturally occurring microorganisms, responsible for the metal leaching activity, in 21 different sewage sludges. The results obtained indicate that the bioleaching of metals is carried out by successive growth of less-acidophilic and acidophilic thiobacilli. Several species of less-acidophilic thiobacilli participate in the sludge acidification, but Thiobacillus thioparus is the most important species. In contrast, Thiobacillus thiooxidans seems to be the only species involved in the acidophilic group of thiobacilli. The growth kinetics of the two groups of thiobaciili was followed in five different sewage sludges. After 5 days of incubation in shake flasks, the pH of the sludge was decreased to about 2.0 and this pH decrease solubilized the toxic metals (Cd: 83–90%; Cr: 19–41%; Cu: 69–92%; Mn: 88–99%; Ni: 77–88%; Pb: 10–54%; Zn: 88–97%). The maximum specific growth rate (μ_max) for the less-acidophilic thiobacilli varied between 0.079 and 0.104 h⁻¹ and that for the acidophilic thiobacilli varied between 0.067 and 0.079 h⁻¹.     

Studies on the effects of sewage effluent on gastropod populations in experimental streams

Population density, biomass, growth and reproduction rate of the gastropods Lymnaea peregra (Müller) and Potamopyrgus jenkinsi (Smith) were monitored over a 21 month period in three experimental earth channels, one carrying clean river water and the others 25 and 50% treated sewage effluent mixed with river water. Each channel was divided into riffle and pool stretches; the abundance and biomass of both species were higher in the riffles. The abundance and biomass of L. peregra were significantly greater (P < 0.01) in the riffle in the presence of effluent. Concentration of effluent did not have a significant effect on abundance or biomass. The abundance and biomass of P. jenkinsi were significantly greater (P < 0.001) in riffle and pool in the absence of effluent. In addition, the abundance and biomass of P. jenkinsi were significantly greater (P < 0.05) in the 25% effluent channel than in 50% effluent. No significant differences in the growth of L. peregra between channels were observed. The average number of eggs and of egg masses laid by L. peregra was significantly greater (P < 0.01) in riffle and pool in the presence of effluent. In the riffle, significantly more masses (P < 0.05) and more eggs per adult (P < 0.01) were laid in the 25% effluent channel than in 50% effluent. No differences were observed in the reproduction rate per adult of P. jenkinsi between the 0 and 25% effluent channels. It is concluded that population differences between channels are probably largely the result of differing mortality rates.