Treatment Effciency of Sugar Effluent usingMembrane Bioreactor

Treatment Effciency of Sugar Effluent using Membrane Bioreactor

Dr. S. Syed Enayathali

Assistant Professor in Civil Engineering, Anna University, BIT Campus,

Trichy

Abstract – An integrated laboratory-scale aerobic membrane bioreactor was used to treat sugar effluent at different HRTs. The MBR is designed to have 108 litres of effective volume. The membrane package is submerged which allows the retention of MLSS to an average of 8000-9000 mg/l. The reactor was run at varying OLR (0.012 to 0.039 kg/COD/m2

/day) and HRT (7, 11, 15, 19, and 23 hrs) at temperature of (29-35°C). The treatment efficiency was found to vary between 73.53 to 95.89 %, which could be rated as the best among the available technologies in practice in India. Hence the models of First Order Model and Stover Kincannon were considered in this work for evaluating bio kinetics coefficients using the experimental data of this work.

Keywords: MBR, MLSS, COD, OLR and HRT.

1. INTRODUCTION

   In recent years, purification of wastewater from various industrial processes has been of prime importance due to limited amounts of water available for direct use. Maintaining drinking water quality is essential to public health. Although wastewater treatment is a common practice for supplying good quality of water from a source of water, the high price of purification, necessity of utilizing the waste products, and maintaining an adequate supply of good quality water have been the major issues. The experiments carried out in the UASB reactor were designed to study the influence of organic loading rate

   (OLR) and hydraulic retention time (HRT) in the treatment of sugar effluent.

2. EXPERIMENTAL SETUP

   An experimental model of MBR, having an effective reactor volume of 108 lit, was used for the study to evaluate the treatment performance. The reactors were fed with substrate using peristaltic pump (Model: PP-30, Miclins). The peristaltic pump a constant flow rate in the range of 2 ml/h to 10 l/h, available with timer and LED display for flow rate of function and time. Five sampling ports were installed along the length of the reactor.

   Biogas produced from the reactor was collected by the water displacement method using Mariotte bottle. The operating temperature of the reactors was in the mesospheric range (29-35°C). The experimental setup of an UASB reactor was shown in figure.1.

   As a case study, effluent samples were drawn on two occasions from an Integrated Milk Plant and analyzed for primary parameters for characterizing the effluent.

   The average values of the biochemical characteristics of the sugar mill effluent are listed in Table

   1.1. Chemical analyses such as pH, BOD, TSS, VSS, TDS, and COD for determination of wastewater quality parameters were conducted according to Standard Methods (APHA, 2005) (3).

   Fig.1 Experimental Setup of UASB System

   Gas collector

   Gas separator

   UASB reactor

   Outlet

   Peristaltic pump

   Effluent

   Inlet

   Influent

   Table1.1; Characteristics of Sugar Effluent

   Sl.no	Parameters	Concentration
   1	pH	6.50
   2	TSS, mg/l	400
   3	TDS, mg/l	2500
   4	TS, mg//l	2950
   5	BOD5, mg/l	1850
   6	COD, mg/l	2650
   7	Total Nitrogen, mg/l	16..35
   8	Total Phosphorus, mg/l	6.75

3. EXPERIMENTAL METHODOLOGY

   The experiment was conducted using synthetic effluent stimulating the real time characteristics of the sugar effluent. A peristaltic pump was used to conduct the experiment for six different flow conditions viz., 3, 5, 8, 10, 12 and 16 lit/hr. The corresponding Hydraulic

   Retention Times (HRT) is7, 11, 15, 19, and 23 hrs.

   The wastewater was fed into the reactor and it was studied for COD removal, as % COD removal efficiency under varied organic loading rates (OLR) and hydraulic retention time (HRT). The varied influent COD applied over system were 2126, 2780 and 3375 mg/l for varied HRT (7, 11, 15, 19, and 23 hrs) and OLR 0.012 to 0.039

   kg/COD/m2/day. Under each operating condition, influent and effluent COD and amount of gas were observed. Using Standard Method of Analysis.

4. MATHEMATICAL MODELING Mathematical modeling is an important

   preliminary step for implementing the wastewater treatment processes guiding systems.

   A.FIRST ORDER MODEL

   The rate of change in substrate concentration in a complete mixed system, considering first-order degradation kinetic and substrate concentration (S) dependence can be expressed as:

   Under steady state conditions, the rate of change in substrate concentration (-dS/dt) is negligible, then Equation reduces to:

   The value of the first-order kinetic constant can be obtained by plotting (So-S)/H versus S, according to Equation. The value of ki is obtained from the slope of the straight line.

   1. 1. ODIFIED STOVER-KINCANNON MODEL

         It is one of the most widely used mathematical models for determining the kinetic constants.The effective volume of reactor is used for the Modified Stover- Kincannon model. This model is expressed as:

         here the substrate consumption rate dS/dt is expressed as:

         Equation (5) is obtained from the arrangement and linearizing of Equation (3)

         The value of the Stover- Kincannon kinetic constants can be obtained by plotting V /Q (So -S) versus V /Q So, according to Equation. The value of Ks and Umax is obtained from the slope of the straight line.

         Graphic representation of experimental data was made according to linearized form of first-order model and Modified Stover-Kincannon model.

5. RESULTS AND DISCUSSION

   After the UASB reactor was stabilized, synthetic wastewater was prepared and used for experimental study.An experiment was conducted for evaluating the UASB system in terms of COD removal. Reactor ran on a continuous basis for 45 days. Influent COD prepared were 2126, 2780 and 3375 mg/l. Initially, COD removal efficiency was poor, after some period of reactor reached to steady state condition and removal efficiency was improved to 82.68%. The graphical representations to assess the reactor performance for different operating conditions were drawn, using observed values. The COD removal efficiency for varying OLR (0.012 to 0.039 kg/COD/m2/day).

   FIRST ORDER MODEL

   800

   700

   y = 7.20x + 560 R² = 0.950

   600

   (So – S) /HRT

   (So – S) /HRT

    

   500

   400

   300

   Series1

   Linear (Series1)

   200

   100

   0

   0 200 400 600 800 1000 1200 1400 1600

   S mg/l

   MODIFIED STOVER-KINCANNON MODEL

   0.00012

   y = 1.244x + 0.019 R² = 0.970

   0.0001

   0.00008

   V /Q (So

   -S)

   V /Q (So

   -S)

    

   0.00006

   0.00004

   Series1

   Linear (Series1)

   0.00002

   0

   0 0.00002 0.00004 0.00006 0.00008 0.0001

   V /Q So

6. CONCLUSION

The UASBR is experimentally found to offer a maximum chemica oxygen demand removal efficiency of 82.68% was achieved at an organic loading rate (OLR) of 0.013 g/COD/m2/day and at a hydraulic retention time (HRT) of 23h. Hence, it can be concluded that UASBR is a credible alternative to reach the reusable standards for treating sugar wastewater streams. The correlation coefficient r2 was chosen as the criterion for choosing the most suitable model to represent organic matter removal kinetics. Considering this criterion, the modified Stover-Kincannon was more suitable than the first-order model.

ACKNOWLEDGEMENT

The authors acknowledge gratefully the authorities of University for having provided all facilitiies for the conductance of the experiment.

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