Biogas Generation Potential from Tapioca Processing Industry Wastes in Tamil Nadu

Biogas Generation Potential from Tapioca Processing Industry Wastes in Tamil Nadu

M.M.C.Rajivgandhi 1, M.Singaravelu 2 and R.Kiruthika 3

1,3Research scholar, 2Professor,

Department of Bioenergy, Agricultural Engineering College and Research Institute, Tamil Nadu Agricultural University, Coimbatore- 641 003.

Abstract

In this study over 100 industries were surveyed belonging to different sago associations like Salem, Attur, Namakkal, Rasipuram, Thammampatti and other parts of Tamil Nadu, India. There are nearly about 1000 sago and starch processing factories are in operation in Tamil Nadu. Sago industries use huge quantities of water during the production of sago and release wastewater. The average production capacity of industries present in Salem sago industries was found to be 6.7 tons per day,

7.6 tons per day by the Namakkal sago industries,

8.2 tons per day by the Attur sago industries, 10.5 tons in Rasipuram industries and 6.3 tons per day by the industries present in Thammampatty and other areas. For the processing of one ton of

tapioca, 20 – 25 m3 of effluent is generated. The

total quantity of biogas that can be generated from the surveyed 100 Tapioca processing unit effluent is 12,627 m3/day. The estimated potential of biogas

production found to be 101 lakhs m3/day.

Keywords: Sago, Tapioca Wastes, Biogas

1. Introduction

   Tamil Nadu produces 40 lakh tonnes of tapioca out of 60 lakh tonnes annually in India. In Tamil Nadu, Salem district alone contributes 34,000 hectares of land under tapioca cultivation. Tamil Nadu stands first in respect of processing of tapioca into starch and sago, hence this crop has now acquired a status of one of the most important commercial crops in the state. There are about 1000 sago and starch industries in Tamil Nadu, in which

   650 to 800 industries are located in and around Salem and Namakkal district.

   Production of Sago and starch from tapioca generates enormous quantity of wastewater which requires treatment before disposal. The treatment of the wastewater obtained from different industrial processes is vital in safeguarding public health and the natural resources. Non-treating of these wastewater contains high organic, inorganic and toxic constituents that creates serious harm to the environment and human health. Industrial wastewater treatment systems employ aeration systems for the treatment in order to reduce excess concentration of pollutants present in the wastewater. Since it is an energy guzzling part in the wastewater treatment process, less importance is being given to this area resulting in the poor treatment and discharging these wastewater containing pollutants, thus harming the environment.

   In recent times, increased awareness on treating wastewater through biological method in particular through anaerobic digestion serves as a potential option to solve the energy crisis and pollution problems pertaining to the disposal of industrial wastewater treatment systems (Bardiya et al., 1996). The idea behind anaerobic digestion of wastewater treatment is to create the contact between wastewater and microorganisms, which feed on the organic materials present in the wastewater resulting in the production of methane and reduction of the organic content present in the wastewater.

   Bio-methanation is an anaerobic digestion technology that has been proven and very well documented, as the appropriate technology for treating the industrial wastewaters. Unlike fossil fuel combustion, biogas produced from waste is considered as CO2 neutral and therefore does not emit additional greenhouse gases into the atmosphere. Methane, one of the potential green house gases, twenty one times harmer than carbon

   dioxide (IPCC, 3rd Assessment report) can be

   proficiently used as an energy source for production of heat and electricity. Bio-methanation systems are used for not only obtaining energy, but also for reducing the pollution to a great extent.

2. Materials and methods

   Waste water collected in selected tapioca processing industries and parameters like pH, total

   Table 2. Production capacities of 100 sago industries and wastewater generation in

   different districts of Tamil Nadu

   Quantity

   solids (TS), volatile solids (VS), total suspended solids (TSS), Biochemical Oxygen Demand (BOD) and Chemical Oxygen Demand (COD) were analyzed as per the APHA (1998) methods.

   The survey work has been carried out to find

   Places of sago processing

   Production

   Capacity (Tons

   /day)

   Quantity of

   Wastewater generated (Litres/day)

   of

   electricity consumed (kWh/ month)

   the wastewater treatment systems adopted, biogas technology employed, waste water generation and sago production. Over 100 industries were surveyed belonging to different sago associations like Salem, Attur, Namakkal, Rasipuram and other parts of Tamil Nadu.

   Salem 158.85 3990000 541000

   Namakkal 227.2 3530000 598000

   Attur 179.6 4065000 768000

   Rasipuram 200.16 3795000 2280000

   Thamampatty

   and others 63 1227500 236000

3. Results and Discussion

   In order to produce 1 ton of sago, 20 to 25 m3 of water is used in sago industries in different unit operations such as washing the tuber, pulping and maceration. The various physicochemical characteristics of the sago processed wasted water are furnished in the Table 1.

   Table 1. Physicochemical characteristics of

   the sago wastewater

   Parameter Unit Magnitude

   pH – 7.2

   Total solids mg/L 7645

   areas

   Total 828.8 16607500 4423000

   The electricity consumption was found to be 17,588 units per month in Salem sago industries, 25,550 units per month in Namakkal sago industries, 37, 684 units per month in Attur sago industries, 24,000 units in Rasipuram association and 23,600 units per month in other sago industries in Thammampatty and other areas.

   The average production capacity of industries present in Salem sago industries was found to be

   6.7 tonnes per day, 7.6 tonnes per day by the Namakkal sago industries, 8.2 tonnes per day by

   Total suspended solids

   mg/L 1405

   the Attur sago industries, 10.53 tonnes in Rasipuram industries and 6.3 tonnes per day by the

   Volatile solids mg/L 1834

   COD mg/L 8000

   BOD mg/L 4400

   The sago processing industry also generates solid wastes up to 10% of the total tapioca processed comprising of 2% of skin or peels and 8% as the process waste called Thippi (solid residue).

   During the survey, it was found that the sago industries are treating the wastewater using conventional anaerobic technology for the production of biogas for the last two decades hitherto. It was found that the average wastewater produced in industries belongs to Salem sago industries association is 1,03,823 litres where as in Namakkal sago industries association is 1,89,500 litres, Attur sago industries association is 1,92,894 litres, Rasipuram sago industries association is 1,99,736 litres and the industries belong to other category produces 1,22,750 litres of wastewater. Production capacities of 100 sago industries and wastewater generation in different districts of Tamil Nadu are furnished in the Table 2.

   industries present in Thammampatty and other areas.

   It was also found that the most of the industries are using the conventional method of treating wastewater like inefficient anaerobic digester using tarpaulin for storing gas and aeration technology. The biogas produced in the inefficient anaerobic digesters are being used for production of electricity in dual fuel generators, biogas run engines and also for roasting purposes in furnace by using locally designed burner. The industries are using the biomass from the local sources partially for satisfying the needs for roasting and boiling processes due to insufficient of biogas production in the inefficient biogas digester. The discharged effluent is being let out into the open field in some industries and in agricultural fields for the production of agricultural crops like paddy, maize, sugarcane, cattle feeds, etc. It was found that the effluent was not rested for pollution before being letting out into the field or to the environment.

   Out of total electricity consumption by the sago industries, motor loading contributes the major part in supplying energy for unloading, peeling, crushing, sizing and polishing processes. It was learned that the motors used for carrying out the

   above said processes were old and high energy consuming.

   3.1 Biogas Generation Potential

   For the processing of one ton of tuber, 20 – 25 m3 of effluent is generated. Quantity of waste water produced from 100 sago industries is about 16607 m3 per day. From one m3 of sago effluent 0.76 m3 of biogas can be obtained with an effluent having

   COD in the range of 7200 – 8300 mg/L. The total quantity of biogas that can be generated from the surveyed 100 Tapioca processing unit effluent is 12,627 m3/day. The estimated potential of biogas production found to be 101 lakhs m3/day.

4. Conclusions

   High potential of biogas and power generation from tapioca processing industries is possible provided hybrid Upflow Anaerobic Sludge Blanket (UASB) bio-methanation plants should be installed (unlike existing conventional bio methanation plants) and the biogas produced from the effluent meets the energy requirements of the industries. Further, it can reduce the dependence on the grid power.

   The biogas generated from tapioca industries contains 50 55 percent of methane, 40 45 percent of CO2 and H2S traces. The presence of carbon dioxide and hydrogen sulphide dilutes the energy content of biogas which could be eliminated by adopting low cost water scrubbing system for the removal of CO2 and H2S traces. Moreover, the sago industries are desperately looking for alternate technologies for tackling the energy shortage and reducing the pollution level of wastewater.

5. References

1. APHA, 1998. Standard Methods for the Examination of Water and Wastewater, 20th Ed. American Public Health Association,

   Washington DC.

2. Bardiya, N., Somayaji, D. and Khanna, S. 1996. Biomethanation of banana peel and pineapple waste. Bioresour. Technol., 58:7376.

3. IPCC Third Assessment Report "Climate Change 2001" and the Synthesis Report. It was published to the web by GRID-Arendal in 2003. Date of Access 19.04.2013. http://www.grida.no/publications/other/ipcc_tar/