PERFORMANCE STUDY ON MODIFIED USABR FOR TREATING DAIRY EFFLUENT

Department of Civil Engineering, Faculty of Engineering and Technology, Annamalai University, Annamalai Nagar 608 002, India

Visit for more related articles at Journal of Industrial Pollution Control

Abstract

Dairy effluent is the most dynamic and varying in its characteristics, as all effluent streams are only from cleaning and washing activities. It is a high COD waste stream with certain inhibitory factors like cream of milk and residues of milk products like gee, butter etc., Anaerobic techniques like UASBR do require specific pre treatment operations for its effective operation and hence they are not widely used. The typical dairy effluents are synthetically prepared for varying COD values [1563.28, 2559.00, 3560.16, 4043.17 and 4571.15 mg/L] and an UASB model was studied. The study was repeated for varying Hydraulic Retention Time [6, 10, 12, 18 & 24 hrs] and performance of model was evaluated in term of % COD removal, VSS in the reactor and biogas generation.

Keywords

UASBR, COD, HRT, OLR, VSS and Biogas

Introduction

Dairy plants in India, Seldom incorporated UASBR in their effluent treatment facilities while only Aerobic Reactors are in popular use. Applications of Anaerobic digester to remove COD at first stage for effective Aerobic Oxidation subsequently are recently introduced. In this study, UASBR which is a time-tested, Proven technology to remove COD up to 80 % for biodegradable waste stream (BOD/COD: 0.4 to 0.6) is evaluated with an experimental model for its performance and a detailed experimental study was conducted.

Experimental Set Up

The experimental setup consists of an UASB Reactor having 25 litres of effective volume. The features and process parameters are listed in Table-1 the schematics of the experimental setup is presented in Fig. 1.

Table 1 Process parameters of the experimental model (UASBR- 25 Lit.)

Fig.1. Schemmatics of the experimental setup.

Experimental Methodology

The model was commissioned with domestic wastewater collected from the sewage treatment facility of our University. The model is found to acclaim the process stabilization with an average COD Removal of 74 % in 80 days.

At least three random samples were drawn from M/s. Hatsun Agro Industries Pvt. Ltd., Karipatti, Salem Dist., T.N., analyzed for critical parameters. The report of analysis, as their average values, is presented in Table 2.

Table 2 Report of analysis (average values)

The real time wastewater was introduced in the reactor with an average OLR of 0.54 Kg COD/m³/day and in stages, mixed with domestic wastewater in proportion with 20 %, 40 %, 60 %, 80 % and 100 %. The process stabilization and acclimatization was get achieved with an average of 74 % COD removal in 30 days.

The synthetic dairy plant effluent is prepared by using milk powder considered for the experiment and introduced after the process stabilization. The chemical composition of the synthetic dairy plant effluent is presented in Table 3. The model was run under different Organic Loading Rates (OLR) ranges from 0.29 to 4.43 Kg COD/m³/day for an average influent COD values of 1563.28, 2559.00, 3560.16, 4043.17 and 4571.15 mg/L and for different Hydraulic Retention Times (HRT) of 6, 10, 12, 18 and 24 hrs respectively.

Table 3 Chemical composition of the synthetic dairy wastewater

Results and Discussion

Fig. 2 shows the maximum COD removal at 77.68 % for 3.55 Kg COD/m³/ day of Organic Loading Rate (OLR).

Fig. 2 Organic loading rate kg COD/m3/d

Fig. 3 shows the maximum COD removal at 77.68 % for Hydraulic Retention Time (HRT) of 24 hrs.

Fig. 3 HRT, hours

The Volatile Suspended Solids (VSS) and Biogas conversion correlation with the % of COD removal efficiency are shown in the Fig. 4 & 5.

Fig. 4 % COD removal

Fig. 5 HRT hours

Conclusion

The modified UASBR is found to treat diary plant wastewater for a maximum of % COD removal efficiency at 77.68 % and 0.318 m³ of gas/kg COD removed. Hence, UASBR can be recommended for removing up to 77.68 % of COD in Dairy effluent and the rest can be removed in the down stream aerobic systems.

Acknowledgement

The authors are thankful to the authorities of Annamalai University for having provided the laboratory facilities

References

1. APHA, l989.Standard Methods for the Analysis of Water and Wastewater.17th Ed. WPCF. New York. BurakDemirel et al. 2005.
2. Anaerobic treatment of dairy wastewaters of review. J. Process Biochemistry. 40 : 2583-2595.
3. Borja, et.al. 1993. Influence of Clay Immobilization supports on the Kinetic constants of anaerobic digestion of dairy industry wastewater. J. Applied Day Science 7 : 367-381.
4. Michal Perle et al. 1995. Some Biochemical aspects of the anaerobic degradation of dairy wastewater. J. Water Research. 29 (6) :1549 -1554.
5. Ramasamy, E.R. and Abbasi, S.A. 2000. Energy recovery from during wastewater impacts of bio film support system on anaerobic CST Reactors J. Applied Energy 65 : 91-98.
6. Gunasegarane G.S. 2002. Energy from dairy waste, National Bio Energy Board Newsletter- Bio Energy News.