Pulp Effluent Treatment Research Articles

Assessment of laboratory scale cylindrical sequencing batch reactor for the treatment of abattoir effluent

Meat factory effluent contains fat, protein, diluted blood, and suspended solids. As a result, nutrient and organic concentrations in this effluent are incredibly high, and residues are slightly solubilized, likely to impact environmental pollution on streams, rivers, and other watercourses if discharged untreated. The biodegradation of abattoir waste was studied using a laboratory-scale cylindrical sequencing batch reactor (SBR) in aerobic mode. The aerobic sludge was collected from the aeration compartment of a paper and pulp effluent treatment facility and cultivated in a 2.83-L Perspex-based laboratory SBR. The raw wastewater comprised 6494 ± 2144 mg/l chemical oxygen demand (COD), 1946 ± 607 mg/l biochemical oxygen demand (BOD), 1722 ± 159 mg/l total suspended solids (TSS), 3062 ± 592 mg/l CaCO3 alkalinity, 7.00 ± 0.27 pH. The duration of a complete cycle was 24 h and comprised four phases: fill (5 min), react (23 h 10 min), settle (40 min) and draw (5 min). The whole experiment was divided into four phases and the dilution was done with the help of domestic sewage. In the first stage, the reactor was fed four times diluted slaughterhouse effluent on a 24-h cyclic operation for two weeks. After achieving a significant reduction in COD, the organic content of the input was raised by lowering the dilution factor. In the second and third phases, the reactor was fed three times and twice diluted samples for two weeks each operating at the same cyclic interval. In the final stage, raw effluent was fed to the reactor for two more weeks. The average COD value of diluted wastewater in the first, second, third and fourth phase was 1040 mg/l, 3168 mg/l, 4800 mg/l, and 5200 mg/l, respectively. The COD removal efficiency at the end of the first, second, third and fourth phase was 83%, 93%, 85% and 97%, respectively. The average BOD value of diluted wastewater at the end of the first, second, third and fourth phase was 1120 mg/l, 610 mg/l, 1502 mg/l, and 1350 mg/l, respectively. The BOD removal efficiency at the end of the first, second, third and fourth phase was 84%, 88%, 85% and 98%, respectively. After 8 weeks, at an organic loading rate of 3.06 kg/m3/d, the final phase has achieved BOD and COD removal efficiency of 98% and 97%, respectively. The pH and alkalinity levels were within acceptable ranges. After two months, the sludge's settling characteristics have improved, and the nitrification efficiency of the reactor was roughly 60% at the time of deactivation of the reactor.

Hemp derived activated carbon supported nanoscale zero–valent iron as a heterogeneous Fenton catalyst for the treatment of pulping effluent

Activated carbon (AC) and nanoscale zero–valent iron (nZVI) have been widely used in wastewater treatment, respectively, for the removal of organics. In this study, hemp fibers were applied to prepare AC by phosphoric acid activation at a carbonization temperature of 400°C. Then nZVI particles were immobilized onto the surface of hemp derived AC (HAC), and the composites (nZVI@HAC) were used as heterogeneous catalysts for Fenton–like treatment of pulping effluent. The as–prepared catalysts were characterized. The optimum conditions for Fenton–like reaction and the reusability of catalyst were investigated. Results showed that nZVI particles were well distributed on the surface of HAC without aggregation. Both HAC and nZVI@HAC have microporous structure. With the loading of nZVI, the catalysts were endowed with magnetism and more active sites. Under the optimal conditions (initial pH 3.0, H2O2 35 mmol/L, 2–nZVI@HAC 3.0 g/L), COD removal rate reached 87.74% of the highest. This work illustrated that the feasibility of HAC as a carrier of nZVI, and nZVI@HAC was an effective heterogeneous Fenton catalyst.

Combined biological and advance oxidation processes for paper and pulp effluent treatment

During recent years, the socio political pressure to develop suitable technologies capable of treating wastewater from the paper and pulp industry has increased due to strict environmental regulations. System closure could potentially lead to substantial operating and discharge cost savings. This study evaluates the potential of combining an aerobic moving bed biofilm reactor (MBBR) (biological) and a Fenton-like system (advanced oxidation processes) for treating recycle mill effluent (RME). The performance of the moving bed biofilm reactor (MBBR) was evaluated at three different hydraulic residence times (HRT). The HRT used were 24, 16 and 5 h and the corresponding total chemical oxygen demand (COD) removals were 55, 49 and 43% respectively. The volatile organic acids (VOA) removals were 63.5, 58.7 and 53% respectively. The Kincannon-Stover model was used to describe the kinetic behaviour of the MBBR. The calculated KB and Umax parameters for the COD were 26.37 g.L−1.d−1 and 15.06 g.L−1.d−1 respectively. For the VOA, the KB and Umax parameters were 11.81 g.L−1.d−1 and 8.87 g.L−1.d−1. The Fenton-like experiments were carried out in batch runs. The first experiments were carried out to determine the optimal reaction parameters. Maximum COD removals were found to be at a pH of 3.33, Fe3+ dosage of 1,000 mg/L and H2O2 of 14.55 mM. Pseudo-first order reaction kinetics was used to describe the kinetic characteristics of the Fenton-like treatment system. The calculated kinetic parameters ηmax (%) and kCOD (min−1) were 53.8% and 0.112 min−1 respectively at a pH of 3.24, Fe3+ dosage of 250 mg/L and a H2O2 dosage of 77 mM.

Physico-chemical treatment of pulping effluent: Characterization of flocs and sludge generated after treatment

ABSTRACTThe present study deals with the treatment of simulated pulping effluent (pH = 11, and total organic carbon (TOC) = 1900 mg/L) by acid precipitation and coagulation-flocculation processes. The maximum TOC removal (= 4845 mg/g Al3+) from the effluent was found with Al2(SO4)3 coagulant. Addition of sufloc (a flocculant) improved the sludge settling significantly. Hydrolyzed mono- and polynuclear species generated from Fe and Al coagulants could have resulted in TOC removal. Thermal analysis of sludge showed release of gases like CO, CO2, HCHO, CH3SH and SO2 during combustion. Afterwards, the dissolved metal species in treated wastewater samples should be removed.

Catalytic hydrothermal treatment of pulping effluent using a mixture of Cu and Mn metals supported on activated carbon as catalyst.

The present study was performed to investigate the performance of activated carbon-supported copper and manganese base catalyst for catalytic wet oxidation (CWO) of pulping effluent. CWO reaction was performed in a high pressure reactor (capacity = 0.7l) at temperatures ranging from 120 to 190°C and oxygen partial pressures of 0.5 to 0.9MPa with the catalyst concentration of 3g/l for 3h duration. With Cu/Mn/AC catalyst at 190°C temperature and 0.9MPa oxygen partial pressures, the maximum chemical oxygen demand (COD), total organic carbon (TOC), lignin, and color removals of 73, 71, 86, and 85%, respectively, were achieved compared to only 52, 51, 53, and 54% removals during the non-catalytic process. Biodegradability (in terms of 5-day biochemical oxygen demand (BOD5) to COD ratio) of the pulping effluent was improved to 0.38 from an initial value of 0.16 after the catalytic reaction. The adsorbed carbonaceous fraction on the used catalyst was also determined which contributed meager TOC reduction of 3-4%. The leaching test showed dissolution of the metals (i.e., Cu and Mn) from the catalysts in the wastewater during CWO reaction at 190°C temperature and 0.9MPa oxygen partial pressures. In the future, the investigations should focus on the catalyst reusability.

ANN-based predictive model for performance evaluation of paper and pulp effluent treatment plant

Neural networks (NNs) have been widely used for complex processes that are poorly described by first principle models, such as wastewater biological treatment systems. In this paper, we propose an Artificial Neural Network (ANN) based predictive model for assessing the performance of paper and pulp effluent treatment plants. Mathematical models were created for the thickener area of the clarifier by correlating process control parameters such as mean cell residence time (θc), initial suspended solid concentration (Co), underflow concentration (Cu) and recycling ratio (R). For any values of Cu, Co, R and θc, area of the secondary clarifier can be determined using the model developed based on ANN. The predicted models give a rational approach to the design of secondary clarifier. The developed models prove consistently well in the face of varying accuracy and size of input data phase.

Sequential batch reactor for eucalypt kraft pulp effluent treatment with Trametes versicolor

AbstractBACKGROUND: A sequential batch reactor (SBR) was used for eucalypt kraft pulp effluent treatment with Trametes versicolor. A 23 full factorial design and response surface methodology were applied to optimise the batch fermentation conditions. Effluent concentration, culture medium and inoculum age were the factors selected for this study in order to optimise the reduction of chemical oxygen demand (COD).RESULTS: The presence of Trametes Defined Medium (TDM) in the fermentation was required to obtain a significant COD reduction. Experiments in the batch reactor confirmed, in general, the predicted results of optimisation developed from Erlenmeyer batch assays. The T. versicolor culture remained active during 42 days of study in the SBR, providing approximately 80% of COD reduction.CONCLUSION: Trametes versicolor may be considered as very promising for the biological treatment of effluents from kraft pulp mills in an SBR system instead of the activated sludge mixed cultures traditionally used. Copyright © 2008 Society of Chemical Industry

Improvement of eucalyptus bleached kraft pulp effluent treatment through combined ozone-biological treatment

The aim of this work is to evaluate the combination of ozonation and biological treatment for reducing recalcitrant organic matter and enhancing the biological treatment efficiency of kraft pulp elemental chlorine-free (ECF) bleaching and similar effluents. Alkaline bleach filtrate was treated with ozone at doses of 100 and 250 mg/L, temperature of 70ºC, and pH 10 (mill conditions). The ozone-treated and untreated effluents were mixed with acid bleaching filtrate to prepare the combined effluents, which were then treated in a bench-scale activated sludge system. The constant biological treatment conditions used were: temperature = 35±2ºC, hydraulic retention time = 12 hours, and sludge retention time = 10 days. Effluents were also fractionated by molecular mass using a membrane with a 500-Da molecular-weight cutoff to characterize the high- and low-molecular-mass organic matter. Ozonation combined with biological treatment resulted in statistically significant increases in removal of COD, BOD5, TOC, lignin, and AOX compared to the effluent without ozone treatment. The high-molecular-mass fractions represented the majority of all components analyzed, and their contribution to total effluent load increased after biological treatment because of the greater removal efficiency of low-molecular-mass organic matter.

Treatment of pulping effluents by using alum and clay - colour removal and sludge characteristics

The effect of clay addition during alum coagulation, on the removal of colour from pulp-and-paper industry wastewaters, was investigated. Four types of clay, namely beige-and brown-sepiolites, calcium- and sodium-bentonites of different mesh sizes were used. Different quantities of alum and clay were applied, either singly or in combination, to the effluents of the wood-based pulp-and-paper mill. Colour of the treated wastewater, the sludge volume index (SVI) and sludge cake resistance (SCR) of the sludge produced were monitored. It was observed that the clays tested were not efficient in colour removal when they were applied on their own. When clay was added along with alum, a certain increase in colour removal efficiency was obtained as compared to alum alone. When alum was used in conjunction with clay, settling characteristics of the sludge produced improved substantially, in terms of both SVI and SCR. Acid activation of the clays did not improve the colour removal efficiency further. However, acid activation of sodium bentonite caused the SVI and SCR values to improve considerably compared to virgin sodium bentonite. Use of different mesh sizes of clays did not exert any significant effect on the colour removal. However, it did exert significant effects on SVI and SCR values as such that the increase in mesh size caused the SVI values to decrease and the SCR values to increase. WaterSA Vol.27(3) 2001: 361-366

Comparative study of fractions from alkaline extraction of wheat straw through chemical degradation, analytical pyrolysis, and spectroscopic techniques

A comparative assessment of spectroscopic and degradative techniques was carried out to characterize fractions from the sodium hydroxide extraction of wheat straw. CPMAS 13C NMR and IR spectra revealed lignin, lignin-carbohydrate complex, and hemicellulose in laboratory and industrial fractions. Preferential removal by alkali of syringyl lignin was observed, and lignin alteration during biological treatment of pulping effluents was indicated by enhanced carbonyl and alkyl signals. Relatively high syringyVguaiacy1 ratio values were obtained by cupric oxide degradation when compared with those from NMR and Py-GC-MS, the latter including ferulic acid. Additional information on straw polymer association and the role of cinnamic acids was obtained. The high guaiacyl content in lignin associated to the hemicellulose suggested bonds between the latter and guaiacyl lignin. Most linked p-coumaric acid was merely esterified, whereas ferulic acid was preferentially associated to lignin by nonsaponifiable bonds.