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Apr 30, 2011 - Laboratory scale studies were performed on the performance of column type sequencing batch reactor (SBR) for the biodegradation of pulp ...

Treatment of pulp and paper mill wastewater: P a g e | 12

An International Journal J. Ind. Res. Tech. 1(1), 12-16, 2011 HATAM Publishers

Journal of Industrial Research & Technology Journal homepage: http://www.hgpub.com/jirt.html

Treatment of Pulp and paper mill wastewater by column type sequencing batch reactor Nadeem Ahmad Khan , Farrukh Basheer, Devendra Singh and Izharul Haq Farooqi* Department of Civil Engineering, Z.H. College of Engineering & Technology, Aligarh Muslim University, Aligarh-202 002, India *Corresponding author, Phone: +91 9412176757, E-mail: [email protected] ARTICLE INFORMATION

ABSTRACT

Article history Received 30 March 2011 Revised 15 April 2011 Accepted 18 April 2011 Available online 30 April 2011

Keywords Aerobic sequencing batch reactor pulp and paper mill wastewater Chemical oxygen demand Organic load Biomass

Laboratory scale studies were performed on the performance of column type sequencing batch reactor (SBR) for the biodegradation of pulp and paper mill wastewater. SBR of volume 3.46 L was fabricated with Perspex material and was seeded with the aerobic seed sludge obtained from a sewage treatment plant. The sludge was acclimatized with 200 mg/L of phenol for two weeks. Subsequently diluted pulp and paper mill wastewater was fed to the reactor at a 24 hour cycle of operation. After achieving significant COD reduction the organic load of the feed was increased by decreasing the dilution and finally raw wastewater has been fed to the reactor. A COD removal efficiency of 87% was achieved during the last phase of the study. The pH and alkalinity were also within the permissible limits. The settling characteristics of the sludge were improved and the granulation process has just started. There was a significant increase in the concentration of volatile suspended solids within the reactor. The turbidity removal efficiency was around 95%. © 2010 HATAM Publishers. All rights reserved.

1. Introduction The total number of pulp & paper mills in the country is estimated to be around 625 equivalents to an installed capacity of over 7.5 million tones which is likely to increase to 8.3 million tones by 2010 and over 14 million tones by the year 2020. The present level of paper consumption in India is around 6.7 million tonnes which makes the per capita consumption of the country a meagre 5.5 kg as against 332 kg in USA and world average of 54 kg. Wood, one of the major raw materials used in the pulp and paper industry, is composed of cellulose fibres carbohydrates such as starch and sugars, as well as lignin which act

as an adhesive substance for the cellulose fibres. The pulp and paper industry breaks down the wood to separate the cellulose from the non-cellulose substances. The raw material is then dissolved chemically so as to form a pulp. The pulp slurry is subsequently dried on a paper machine to produce a paper sheet. The addition of dyes, coating materials or preservatives can occur at some point of the process to produce the required quality of paper or associated product. Physical chemical treatment of pulp and paper industry wastewater treatment through Primary

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Treatment of pulp and paper mill wastewater: P a g e | 13 clarification, sedimentation or Flotation removed more than 80% of the suspended solids at surface loading rates of up to 1.4 m3/m2 h (Saunamaki et al., 1997). Dissolved air Flotation is an accepted process for the removal of suspended solids and has been used in many wastewater treatment process streams, There are numerous biological treatment systems available, the most common being the activated sludge process. Paper mills having activated sludge plants typically operate at mean organic loading rates (OLR) ranging from 0.07 to 0.21 kg BOD/kg mixed liquor suspended solids (MLSS) These generally show very high removal efficiency for both BOD and COD values. Poor settlement (bulking) has caused operational problems in ASP. Bulking is deemed to be occurring when the Sludge Volume Index exceeds a value of about 120 and this can result in excessive concentrations of solids being discharged in the final effluent when the solids handling capacity of the final settlement tank is exceeded. It can also create problems in ensuring that the correct amount of sludge is recycled back to the aeration tank to maintain the MLSS at a sufficient concentration to guarantee efficient treatment. Other types of bio-film process have also been used for the treatment of paper mills wastewaters. High-performance trickling filters using plastic media have been used successfully use as a pre-treatment stage prior to an activated sludge plant (Moebius et al., 1990). Biological aerated filters (BAF) have also been used to treat wastewaters from paper mills. Mean removal efficiencies of greater than 80% for both COD and BOD could be achieved with hydraulic retention times (HRT) of about 0.75h (Kantardjie et al., 1997). Typical COD removal efficiency in the anaerobic treatment of paper mills wastewaters is generally around 80%. Using bio-film reactors, removal efficiencies of up to 90% were obtained with hydraulic retention times as low as 19 min. Chen, and Horan (1998a), Chen and Horan (1998b) have reported the use of a two-stage anaerobic-aerobic approach to remove COD and sulphate from the wastewaters generated at an integrated newsprint mill. COD and sulphur removals were 66% and 73%, respectively. In general, anaerobic digestion is carried out at mesophilic temperatures, 35±37°C. Although activated sludge plants have been the most common wastewater treatment process, there are several problems with the process. It produces sludges with very variable settlement properties, it is sensitive to shock loading and toxicity, and its capacity to remove poorly biodegradable toxic substances is limited. Studies were conducted in Finland on the use of preozonation to prevent process failure, to improve the purification efficiency and to reduce pollution to receiving watercourses.

The main tertiary treatments which have been employed to date at a few sites in the industry are membrane processes, especially ultra filtration. This process is a pressure driven separation, based on the selective permeability of a membrane, which can serve as a secondary clarifier as the final liquid solids separation step. Das et al. (2011) studied the treatment of pulp and paper waste and achieved COD removal efficiency in the range of 70.3% to 79.8%. An optimal strain (S308: CAGGGGTGGA) was selected to study the population dynamics and diversity of the bacterial community. The RAPD-polymerase chain reaction (PCR) fingerprints showed very high polymorphism of the genetic bands (78–100%). The Shannon-Weaver index was high and varied over time with the COD removal. The RAPD technique is quick, simple, and inexpensive, and it has been widely used in species classification and phylogenetic analysis, resistance gene identification, genome analysis, and genetic analysis of populations (Das et al. 2011). Not surprisingly, RAPD analysis has been one of the more frequently used DNA-based methods for assessing the microbial genetic diversity and evolution of biological wastewater treatment systems (Becker et al. 2001; Zhang et al. 2008). The main objectives of their study was to analyze the microbial dynamics of SBR treating alkaline peroxide mechanical pulp (APMP) process wastewater using the RAPD method and to determine the treatment efficiency as well as characterize the process wastewater using the gas chromatography-mass spectrometry (GC-MS) technique. (Zhan et al., 2010). Studies conducted by Sirianuntapiboon et al. (2006) reveal that polyelectrolyte had no effect on pollutant removal. At optimum conditions, greater than 97% of color and 77% of total COD were effectively removed with a total operating cost of approximately 0.29 USD/m3 wastewater. First order rate kinetics best explained the reduction of colour and total COD concentration, the model fitting the actual data very well. For the continuous mode, the treatment process reached the steady state condition within 2.15 h and the efficiency of colour and total COD reduction was greater than 91% and 77%, respectively. Column based Sequencing Batch Reactor has gained popularity as a better biological treatment system owing to low space and power requirement, ability to degrade toxic pollutants and to withstand higher organic loads and shock loads (Thompson et al., 2001). The present study was carried out to assess the feasibility of a column type SBR for the treatment of pulp and paper mill wastewater.

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Treatment of pulp and paper mill wastewater: P a g e | 14 The reactor was seeded with the aerobic sludge obtained from the aeration tank of the pulp and paper wastewater treatment plant. Initially the sludge was fed with phenol for three weeks so as activate phenol degrading bacteria. Subsequently paper industry wastewater was fed to the reactor. The characteristics of the wastewater obtained from the industry are shown below in Table 1. The analytical techniques used in this study were performed according to the methods described in Standard Methods [APHA AWWA, 2005]. Samples were periodically analyzed for residual carbon concentration (COD) (standard code: 5220), BOD5 (standard code: 5210B), DO and MLSS concentration (standard code: 2540D). The DO concentration was measured by DO meter. The pH was monitored by pH meter (systronics pH Meter 900). Sludge volume index (SVI) value was calculated according to values of sludge volume (SV) and MLSS (standard code: 2710D).

Figure 1: Experimental Setup 2. Material and Methods Pulp and paper industry wastewater, was collected form Naini Pulp and Paper Industries Co., Ltd, Kashipur, UP India, was used in this experiment. Laboratory scale Sequencing Batch Reactor System (SBR) was fabricated with Perspex material and had a total volume of 3.46-liter. The dimensions of the reactor were 7 cm in diameter and 90 cm in height. One airpump system, model EK- 8000, 6.0 W, was used for supplying diffused air to the reactors. The entire experimental setup was automated with Solenoid valve, Gate valves followed by automatic on-off timers with different time-dependent cycles. A tank of 12 liter capacity was provided for the influent to the SBR . The experimental set up in shown in Figure 1. Table 1: Characteristics of the used in the Study Wastewater Characteristics Chemical Oxygen Demand (COD) (mg/L) Biochemical Oxygen Demand (mg/L) Turbidity (NTU) Dissolved Oxygen (D.O) (mg/L) Volatile suspended solids (mg/L) Alkalinity (mg/L of CaCO3) pH

3. Results and Discussion The present study was performed to assess the performance of column type sequencing batch reactor for the treatment of pulp and paper mill waste. The sludge obtained from the pulp and paper industry of Kashipur was acclimatized with phenol for three weeks In order to activate the phenol degrading bacteria. The is done so as to enhance the population of microorganisms responsible for the biodegradation of phenolic compounds as the pulp and paper industry waste contain a variety of phenolic compounds including chlorophenols. Subsequently wastewater of paper industry was fed to the reactor at 24 hour cycle. It was found that the COD removal efficiency was less and was around 35%. The influent wastewater was then diluted to COD of around 6oo mg/L and the reactor showed a better COD removal efficiency. The influent COD was then increased till optimum COD

Wastewater Range 2784 – 1750 680 – 1160 680 – 490 Nil 3500 – 2250 1250- 780 8.6-7.8

Figure 2: Performance of SBR during 250 days operation for Influent, effluent and COD removal efficiency

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Treatment of pulp and paper mill wastewater: P a g e | 15 The variation of influent and Effluent pH is shown in figure 4. It is seen that the influent pH is most of the time above 8. However, the effluent pH is between 7 and 8 for most the time. Figure 5 shows the variation of effluent alkalinity with time. The effluent alkalinity was above 1000 mg/L for most of the time. Sufficient alkalinity was present in the reactor throughout the experiment time 2000 1500 Alkalnity

Figure 3: MLVSS buildup in the SBR during the operation of SBR

1000 500 0 0

50

100 150 No. of days

200

250

Figure 5: Variation of Effluent Alkalinity with Time

Figure 4: Variation of pH with Time. removal efficiency was obtained. Later on the raw wastewater was fed to the reactor and the performance of the reactor was monitored in terms of COD removal. Figure 2 shows the variation of influent, effluent COD and COD removal efficiency with time. It is seen that despite variation in the influent COD values the effluent COD became stable after nearly 60 days of operation of the reactor. The microorganisms have become acclimatized to the pulp and paper industry wastewater and variation in influent COD does not affect the effluent COD and COD. The results of the study indicate the efficacy of SBR for treating pulp and paper industry wastewater at 24 hour cycle. The cycle may be reduced as the microorganisms have been acclimatized to the wastewater. Figure 3 shows the buildup of mixed liquor volatile suspended solids (MLVSS) with time. It is seen that there was a continuous increase in the volatile suspended solids concentration with time during the initial phases. Later on the concentration of MLVSS was more or less constant. This was achieved after wasting periodically the excess sludge from the reactor otherwise there could have been excessive buildup of MLVSS that may result in decrease efficiency because of substrate diffusion problem.

Figure 6: Variation of Influent and Effluent Turbidity with Time The variation of influent and effluent turbidity with respect to time is shown in Figure 6. It is seen that the influent sample was very turbid and possessed colour. However the effluent concentration of turbidity was reduced a lot. This may be because of trapping of turbidity causing colloids in the sludge blanket of the reactor. 95% turbidity removal efficiency was obtained in the reactor. The SBR system used in the study was efficient in removing the turbidity and colour form the wastewater. Conclusion The reactor system SBR was found effective for the treatment of pulp and paper mill wastewater. The COD removal efficiency was around 87% when the reactor operation was terminated. There was a large

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Treatment of pulp and paper mill wastewater: P a g e | 16 variation in the influent COD values. However, the effluent COD was more or less constant. There was continuous build up of MLVSS in the system and it can be concluded that the column type SBR is effective in retaining the biomass an essential feature for all biological reactors. The pH an alkalinity of the effluent was within the acceptable limits. There was an efficient turbidity removal and the turbidity removal efficiency was around 95%. The results showed that column type SBR may be a better option for the treatment of pulp and paper mill wastewater. References APHA (2005). Standard Methods for the Examination th of Water and Wastewa ter. (21 ed.). American Public Health Association, Washington, DC. Becker, Y., Meondez, M.P., & Rodriguez, Y. (2001). Polymer modified asphalt. Visc. Technol., 9, 3950. Chen, W., Horan, & N. J. (1998). The treatment of high strength pulpand paper mill effluent for wastewater re-use- II) Biological sulphate removal from effluent with low COD/sulphate ratio. Environ. Technol. 19, 163-171. Chen, W., Horan, & N. J. (1998). The treatment of high strength pulp and paper mill effluent for wastewater re-use- III) Tertiary treatment options for pulp and paper mill wastewater to achieve recycle. Environ. Technol. 19, 173-182.

Das, A., Stöckelhubera, K. W., Jurka, R., Jehnichena, D., & Heinricha, G. (2011). A general approach to rubber–montmorillonite nanocomposites: Intercalation of stearic Acid. Applied clay science, 51 (1-2), 117-125. Sirianuntapiboon, S., & Yommee, S., (2006). Application of a new type of moving bio-film in aerobic Sequencing batch reactor (aerobic-SBR). J. Environ. Manage., 78 (2), 149–156. Thompson, G., Swain, J., Kay, M., & Forster, C. F. (2001). The treatment of pulp and paper mill effluent: a review. Bioresour. Technol., 77, 275– 286. Kantardjie & Jones, J.P. (1997). Practical experiences with aerobic biofilters in TMP (thermomechanical pulping), sulfite and fine paper mills in Canada. Water Science and Technology. 35(2&3), 227– 234. Saunamäki, R. (1997). Activated sludge plants in Finland. Water Sci. Technol., 35, 235–242. Zhang, J., Wang, J. L., Wu, Y. Q., Wang, Y. P., & Wang, Y. P. (2008). Preparation and properties of organic paly-gorskite SBR/organic palygorskite compound and asphalt modified with the compound. Constructed Build.Mater., 22, 18201830. Zhan P., Chen, J., He, G., Fang, G., & Shi, Y. (2010). Microbial dynamics in a sequencing batch reactor treating alkaline peroxide mechanical pulp and paper process wastewater. Environ. Sci. Pollut. Res., 17 (9), 1599–1605.

Journal of Industrial Research & Technology, Volume 1, Issue 1, April 2011