Paper Mill Wastewater Treatment Plant Research Articles

BIOCONVERSION OF CELLULOSE INTO HYDROGEN, BIOGAS AND ORGANIC ACIDS USING MICROBIAL CONSORTIUM FROM A PULP AND PAPER MILL WASTEWATER TREATMENT PLANT

This study evaluated the potential of a microbial consortium collected from a pulp and paper mill wastewater treatment plant (WWTP) for converting cellulose to hydrogen, biogas and organic acids. Fermentation tests were conducted in batch reactors fed with different concentrations of cellulose as substrate: (C1) 2.0 g L -1; (C2) 5.0 g L -1 and (C3) 10.0 g L -1. The parameters investigated were hydrogen, biogas, organic acids, carbohydrates and pH. The maximum hydrogen production was 14.77, 39.25 and 22.53 mmol L -1, and the maximum methane was 4.40, 3.72 and 9.56 mmol L -1, for C1, C2 and C3, respectively. Butyric acid was the main metabolite generated, with maximum concentrations of 2.2, 1.8 and 2.2 g L -1 for C1, C2 and C3, respectively. The decrease in hydrogen production was accompanied by the production of methane, acetic acid and hydrogen sulfide in the three tests, probably related to hydrogenotrophic methanogenesis, homoacetogenesis and sulfidogenesis, respectively. The phylogenetic characterization of the bacterial community was performed by cloning and sequencing analysis. The microorganisms identified in the consortium were similar (> 95%) to Clostridium sp., Klebsiella sp., Routella sp. and Desulfovibrio sp. These genera were associated with hydrogen production, degradation of cellulosic substrates, and/or hydrogen-consuming microorganisms.

Dynamic Modeling of an Activated Sludge Process: Case Study on Paper Mill Effluents

AbstractThe aim of this paper is to propose a step by step method to establish and validate a relevant, dynamical model of the activated sludge process for the paper mill industry. The model is established by considering the specificities of the effluent to be treated. It uses the biochemical oxygen demand (BOD) measurement, which allows a direct correlation between the state variables of the model and the measurements. This model is validated on a pilot plant of semi-industrial size fed with industrial paper mill effluents. The parameter estimation is based on an analysis of the sensitivities. The results are compared with a model based on chemical oxygen demand (COD) partitioning which is issued from the simplification of the activated sludge model number 1 (ASM1) model. Finally, the model dealing with BOD measurements not only shows the best performances, but is also the easiest to implement, overcoming one main obstacle to efficient monitoring and control in paper mill wastewater treatment plants.

Biodegradation of Kraft Lignin by a Bacterial Strain <i>Sphingobacterium</i> sp. HY-H

A lignin-degrading bacterium was isolated on mineral salt medium amended by lignosulfonate (L-MSM) agar from the activated sludge of a pulp and paper mill wastewater treatment plant and identified as Sphingobacterium sp. HY-H by biochemical tests and 16S rRNA gene sequencing. The maximum kraft lignin (KL) degradation capability of strain HY-H was determined to be 28.2% on a COD basis under the optimal conditions of pH 7.0, temperature 30°C, and KL to nitrogen (as NH4Cl) ratio of 2 by mass. Moreover, growth kinetic studies showed the KL tolerance of strain HY-H was relatively high and the analysis of KL degradation products by GC-MS revealed the formation of low-molecular-weight aromatic compounds (LMWACs), such as guaiacol, vanillin and vanillyl alcohol, indicating that the strain HY-H can oxidize guaiacyl (G) units and syringyl (S) units in lignin structure. In addition, some low molecular ketone compounds such as 4-hydroxy-2-butanone and methyl vinyl ketone were detected in the inoculated sample after 48h, further validating the partial but possible degradation of KL by strain HY-H.

Reduced Sulfur Compound Emissions from Kraft Pulp and Paper Mill Wastewater Treatment Plants

Reduced Sulfur Compound Emissions from Kraft Pulp and Paper Mill Wastewater Treatment Plants

Reduced Sulfur Compound and Methane Emissions from Kraft Pulp and Paper Mill Wastewater Treatment Plants

Reduced Sulfur Compound and Methane Emissions from Kraft Pulp and Paper Mill Wastewater Treatment Plants

Effects of initial cultivation pH on fermentative hydrogen production from xylose using natural mixed cultures

Batch tests were conducted to select a good natural mixed microflora seed source and determine its optimal initial cultivation pH to elevate hydrogen production from xylose (20 g-COD/L). Hydrogen production efficiency was evaluated using the hydrogen yield (HY) and maximum hydrogen production rate (HPR m). Sewage sludge was shown to have higher HY and HPR m than other biological sludges collected from distillery, food and paper mill wastewater treatment plants. The experiments of pH effect were conducted at pH 5–8 and 35 °C. The experimental results indicate that the initial cultivation pH markedly affected HY, HPR m, liquid fermentation product concentration and distribution, butyrate/acetate concentration (HBu/HAc) ratio and metabolic pathway. For sewage sludge, its optimal initial cultivation pH for hydrogen production was 6.5 with peak values of HY 1.3 mol-H 2/mol-xylose, HPR m 0.25 mol-H 2/L-day, butyrate concentration 5780 mg-COD/L and HBu/HAc ratio 4. However, a pH change of 0.5 units from pH 6.5 decreased hydrogen production efficiency by 23%. Strategies based on the experimental results for optimal hydrogen production from xylose are proposed.

Monitoring of a paper mill wastewater treatment plant using UV/VIS spectroscopy

A submersible UV/VIS spectrometer was used to monitor a paper mill wastewater treatment plant. It utilises the UV/VIS range (200-750 nm) for simultaneous measurement of COD, filtered COD, TSS and nitrate with just a single instrument. The instrument measures in-situ, directly in the process. Paper mill wastewater shows typical and reproducible spectra at various process measuring points. There is a relative maximum at 280 mm due to the absorbance by dissolved organic substances, mainly ligninic acids. Comparison of absorbance spectra distinctly shows the decrease of this peak, indicating biological degradation throughout the treatment process. Summarising, one can say that paper mill wastewater cannot be monitored by a simple UV probe measuring only the absorbance at a single wavelength. The required information can only be gained from the whole spectra. Regarding plant control it is suggested that only the overall spectral information is used. Calibrations to conventional parameters are now merely carried out for purposes of reference-checking.

Improved Biodegradability of Ligninsulfonic Acid and Wastewater after Ozonation

A considerable amount of the constituents in wastewater of the pulp and paper mill industry is not biodegradable. As an alternative to the usual coagulation, flocculation, and sedimentation of the substances, the combination of ozonation and a subsequent biological treatment step has been proposed. Ozonation in combination with microbiological treatment was employed to remove ligninsulfonic acid and refractory organic substances from the effluent of a paper mill wastewater treatment plant. Laboratory experiments showed that ligninsulfonic acid was converted into low‐molecular‐weight acids which were biodegradable.

Biodegradation of poly(vinyl alcohol) with different molecular weights and degree of hydrolysis

The biodegradability of poly(vinyl alcohol) (PVA) was investigated under different conditions by respirometric determinations, iodometric analysis, and molecular weight evaluation. Microbial inocula derived from the sewage sludge of municipal and paper mill wastewater treatment plants were used. A rather active PVA-degrading bacterial mixed culture was obtained from the paper mill sewage sludge. Significant biodegradation levels within quite short incubation times were obtained in liquid cultures in the presence of acclimated microbial populations. The influence of some polymer properties such as molecular weight and degree of hydrolysis on the biodegradation rate and extent was investigated in the presence of either the acclimated mixed bacterial culture or its sterile filtrate. Kinetic data relevant to PVA mineralization and to the variation of PVA concentration, molecular weight, and molecular weight distribution revealed a moderate effect of the degree of hydrolysis. The molecular weight appeared to be not a limiting factor of microbial attack. Comparison of the degradation process in the presence of either bacterial cells or their culture filtrate highlighted the ability of some microbial strains to utilize polymer chains having 5–10 kD molecular weight. This result suggests the occurrence of two PVA degradation mechanisms: a random-type attack and a terminal unzipping depolymerization process of polymer chains. Copyright © 2000 John Wiley & Sons, Ltd.

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.

Performance Increase of Papermill Waste Water Treatment Plants by a High-Capacity Trickling Filter Inserted as First Biological Stage

In many cases, it will be advisable to enhance operational safety and increase degradation performance of existing activated sludge plants by inserting a high-capacity trickling filter with plastic media. Easily degradable carbohydrates are largely decomposed in the trickling filter at low energy requirements. This allows the subsequent activated sludge stage to be set to reduced BOD sludge load levels which are required for efficient COD elimination, because the volume load has been reduced and a higher biomass concentration can be obtained at a lower sludge volume index. In the light of several years' pilot testing of numerous different effluents, and of knowledge derived from observations of several industrial plants in the paper sector, precise rating directives can now be given for plants of this type. It has proven advantageous to discharge the trickling filter effluent directly into the activated sludge plant without intermediate clarification. The effluent temperature, which frequently exceeds 35°C, is reduced by up to 10°C in the trickling filter. This improves the conditions prevailing in the activated sludge plant, thus permitting limit values for the discharge of effluents into surface waters to be adhered to.

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.