Conversion of Biodegradable Waste to Fertilizer and Energy

Laxmi Pande

Department of Civil Engineering G.H. Raisoni College of Engineering

Nagpur, India laxmi.p7@gmail.com

Dr.P.B.Nagarnaik Department of Civil Engineering

G.H. Raisoni College of Engineering Nagpur, India

pnagarnaik@rediffmail.com

Abstract—Municipal solid waste management and treatment is a major problem faced by municipal bodies all over the world especially India. Due to increasing population and changing life style, the volume of the waste increases exponentially. In India, the waste is disposed by landfilling, composting, etc. However, these methods have certain disadvantages. In addition to this, Energy Crisis is another crucial problem faced by India. This paper presents a novel technique for treatment of biodegradable waste (which forms a major part of MSW). It involves processing of Biodegradable Waste by thermal process in presence of catalyst at high temperature to give liquid fertilizer and coke as product. This technology has a definite goal of exploiting the commercial aspects of two universal problems i.e. problem of managing the biodegradable waste in the municipal solid waste and overcoming the fuel shortage indigenously.

Keyword-Biodegradable waste, Municipal Solid Waste (MSW), Energy Scenario, Thermal process

I. INTRODUCTION MSW generation in India is increasing due to increasing

urbanization, increasing population and changing lifestyle. The MSW generation in India is about 90 million tonnes per year. The per capita increase in MSW generation is projected at a rate of 1-1.33 % annually ( Seema U et. al [1])[2]. With increasing population of 3-3.5% per annum, the yearly waste generation is expected to increase by 5 %. The generation rates in different cities of India are shown in Table 1.

For this rise in generation, it is very important to know the

composition and accordingly the waste can be treated and disposed without harming the environment and hence our eco-system. The composition of MSW generated in India varies considerably from point to point. The typical composition is shown in Table 2. The major fraction of MSW is biodegradable matter (41%).

The disposal methods adopted in India are mainly land dumping, composting, thermal process, biological process. However the most practiced is dumping. The status of municipal solid waste treatment and disposal in some of the metro cities is shown in Table 3.

City Population (>20 Lac)

2004

Waste Generation

(TPD)

Pune 25,38,473 1175

Mumbai 1,63,70,000 5320

Delhi 1,03,06,452 5922

Kolkata 45,72,876 2653

Chennai 43,43,645 3036

Banglore 43,01,326 1669

Hyderabad 38,43,585 2187

Ahmedabad 35,20,085 1302

Kanpur 25,51,337 1100

Nagpur 20,52,066 504 Source: CPCB,2004

Table 2: Composition of municipal solid waste in India[1]

Description Percent by weight Vegetable, leaves

40.15

Grass 3.8 Paper 0.81 Plastic 0.62 Glass/ceramics 0.44 Ash 41.81 Metal 0.64

Laxmi Pande et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 5, Issue No. 2, 277 - 281

ISSN: 2230-7818 @ 2011 http://www.ijaest.iserp.org. All rights Reserved. Page 277

IJAEST

Tabke 3: Status of municipal solid waste treatment and disposal in metro cities[4]

Metro City Solid waste collection (tonned/day)

Treatment (tonnes/day)

Bangalore 2000 200 Bombay 55,355 500 Calcutta 3692 Nil Delhi 4000 300 Hyderabad 1566 100 Pune 700 50 Chennai 3124 Nil

Metro City

Mode of disposal (%)

Dumping Composting Others Bangalore 90 10 - Bombay 91 9 - Calcutta 100 - - Delhi 93 7 - Hyderabad 94 6 - Pune 93 2 7 Chennai 100 - -

It can be seen that most of the waste is disposed by land dumping. For the business as usual scenario the land requirement for the disposal would increase from 195.4 sq.km in 1997 to 590.1 sq.km in 2021 (S.Gupta et al [5]). This area is very huge. Land dumping includes open dumping and landfilling. Open dumping is the cheapest and oldest mode of MSW disposal. The waste is untreated, uncovered and not segregated. It attracts flies and rodents and generates foul smell. Landfilling leads to groundwater contamination due to percolation of leachate, air pollution due to various green house gases that are evolved into the atmosphere adding to the Global Warming and nuisance to environment. Another method by which MSW is disposed is incineration, but it is not fully exploited because of the low calorific value of MSW and the ash obtained contains harmful toxins. Composting can be used for small scale generation but large amount of waste cannot be treated by this method due to the restrictions of the available area. Moreover this process is time consuming. Atleast a month is required for the formation of good compost. Citing these reasons, it is very essential to develop a technology which can treat large amount of waste in short duration. Moreover, the technology should be eco-friendly and should not add to the pollution that may have caused if the waste was untreated. It can be seen from the composition, the major part of MSW consist of biodegradable waste. The biodegradable waste has its origin from plant and animal sources. Food waste, vegetable waste, paper waste, biodegradable plastic waste alongwith slaughterhouse waste, human waste, animal waste comes under biodegradable waste. This biodegradable waste

contains high N-P-K (Nitrogen-Phosphorus-Potassium) value. Also as it is organic waste, the energy that can be extracted from it is substantial. The energy potential of Biodegradable waste can be calculated as shown below:

Total conversion of waste in energy : W tonnes (biodegradable waste) * Z% ( energy in for m of fuel)

Net Calorific Value of fuel : NCV k-cal/kg. Energy recovery potential (kWh) = NCV x W x

1000/860 = 1.16 x NCV x W x Z Power generation potential (kW) = 1.16 x NCV x W/

24 = 0.048 x NCV x W x Z Conversion Efficiency = 25% Net power generation potential (kW) = 0.012 x NCV

x W x Z From the above formula, we can estimate the quantity of energy that is wasted if this energy is not recovered.

Energy Scenario

India is a developing country. Energy is a very important input for the economic growth of the country. The per capita consumption of energy is very low as compared to other developed nation. Due to continous growing economy, this consumption has to increase in coming years. The present per capita consumption of energy is 530 kg of oil equivalent(kgoe).[6] J. Parikh and K. Parikh summarize the energy scenario in India. The details of primary energy supply is given in Table 4.

Table 4 Primary Energy Supply in India[7]

Energy Source

Units Domestic Qty.

Net imports

Energy*

%

Coal Mt 457 29 8343 41.9 Lignite Mt 34 0 408 2.0 Crude Oil Mt 34.1 121.7 Petroleum products

Mt 34.1 121.7 6523 32.7

Natural gas

Bcm 32.4 0 1221 6.1

LNG Mt 0 8.3 427 2.1 Hydro energy

TWh 120.9 5.3 454 2.3

Nuclear Energy

TWh 17 0 186 0.9

Others 11.9 Total Energy Supply

19924 100.0

It can be seen from Table 4 that coal contributes to about 42% of Total Primary Energy Supply (TPES). About 78% of coal contributes to the electricity production in India. The Planning Commission of India in its report has projected India’s electricity requirement to 3597 GWhr in 2030 as against 761 GWhr in 2006 at GDP (Gross Domestic Product) growth rate of 8% [8]. For this energy requirement, domestic production and imports for 8% GDP growth rate in 2030 is projected as shown in Table 5.

Laxmi Pande et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 5, Issue No. 2, 277 - 281

ISSN: 2230-7818 @ 2011 http://www.ijaest.iserp.org. All rights Reserved. Page 278

IJAEST

Table 5: TPCES: Total primary commercial energy

supply[8] Fuel Commercial

energy requirement in 2030

Assumed domestic production capacity 2030

Imports 2030

Import 2030 Percent

Oil(Mt) 453 35 418 93 Natural Gas (Mtoe)

93 100

Coal(Mtoe) 923 560 363 39 Others (Mtoe)

82 - 0 0

TPCES 1553 - 781 50 It can be seen from Table 5 that by 2030 India will depend on 50% imports for energy. 39% of the coal requirements will have to be satisfied by importing good quality Coal. Moreover, the quality of coal should also be improved. The Planning Commission in its report has stated the policy for production of improved quality of coal having low ash content. To overcome the above mentioned problems of MSW treatment and energy crisis, a novel technique was developed for treatment of Biodegradable waste by thermal process. This process is completely eco-friendly. There is total conversion of Biodegradable waste into value added products.

II THERMAL PROCESS

This process involves catalytic conversion of Biodegradable Waste into liquid fertilizer and coke at high temperature at atmospheric pressure in absence of any atmospheric oxygen. The process was carried out at our lab at Nagpur, India. The process flow sheet is shown in fig.1 Catalyst used is a patented catalyst. The brief description is as follows:

1. Churner: The Biodegradable waste is first churned so as to attain uniform viscosity in a churner.

2. Reactor: It is then fed to the reactor which is an insulated stainless steel cylindrical reactor heated by electrical heating coils to achieve a maximum heating temperature of 500oC The necessary provision is made on the reactor for mounting the gadgets for measuring pressure, temperature and collection of liquid product from the reactor.

3. Condenser: The gaseous output from the reactor is passed through a double walled condenser with inlets and outlets for cooling water. The gaseous product at a temperature of around 350oC are condensed to around 30-35oC.

Fig.1 Process Flowsheet

4. Receiver: The condensed gas in the form of liquid

fertilizer is collected in the receiver. The provision is made for collecting the uncondensed gases in to gas collector. The arrangement to measure the volume and rate of flow of liquid continuously or intermittently at any point of time is made in this section.

5. Control Panel: The complete process is controlled from the control panel. Optionally the process can also be controlled from a computer.

Output Yield Data

The major process parameters and product yields are given in Table below. The evolved vapors are condensed to collect gas and liquid products.

Table 6 Process parameters Feed Biodegradable waste

(Vegetable, Restaurant) Contaminants 5% on feed (Plastic, rubber,

tyre) Catalyst 1 % on feed Temperature Pressure Atmospheric Batch cycle time

3-4 hrs

Table 7. Product yield

The product yields Quantity (wt %)

Gas 10-15

Liquid 70-80

Coke 7-15

Laxmi Pande et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 5, Issue No. 2, 277 - 281

ISSN: 2230-7818 @ 2011 http://www.ijaest.iserp.org. All rights Reserved. Page 279

IJAEST

The Municipal Solid Waste cannot be segregated into pure biodegradable form. It is bound to have some contaminants in the form of plastics, rubber, etc. These contaminants are added as it is present in the feed. The feed can be varied with its composition like pure vegetable waste, pure restaurant waste, or a mixed feed.

III ANALYSIS OF PRODUCT

Liquid Product: The Analysis of the output liquid product is shown in Table 8.

Table 8. Analysis of liquid product Sample Liquid

N% 0.4-0.5% P% Not Detected

K(mg/L) 0.5-2 S% 0.001-0.005 Cl% 0.1-0.6

As the liquid is in water base, the N-P-K values are that of a diluted sample of fertilizer in water. As the dilution increases, the value decreases further. The presence of sulphur and chlorine in output liquid suggests the possibility of having pesticidal properties as well. The organochloro analysis of the liquid is shown in Table 9.

Table 9: Organochloro analysis of liquid product Chlorinated pesticides

Measurement Unit

Result

Aldrin ppb 1.3-6 Alpha Endosulphan

ppb 5-12

Deildrin ppb 10-25 The liquid product is found to have both fertilizer and pesticidal properties. The properties of the above mentioned pesticides are shown below: Aldrin :

Fig.2 Structure of Aldrin[9]

Table 9: Properties of Aldrin[9]

Aldrin is mostly used as pesticide.

Alpha Endosulphan:

Fig.3 Structure of Alpha Endosulphan[10]

Table 10: Properties of Alpha Endosulfan[10]

IUPAC:

an equimolar mixture of 2 asymmetric, twisted-

chair conformers of (5aR,6S,9R,9aS)-

6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepine

3-oxide

CAS:

(3α,5aβ,6α,9α,9aβ)-6,7,8,9,10,10-

hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzodioxathiepin

3-oxide REG. NO.: 959-98-8

FORMULA: C9H6Cl6O3S

ACTIVITY: insecticides (cyclodiene insecticides)

PHYSICAL STATE Brown Crystals

SOLUBILITY IN WATER 0.32 mg/L

Properties

Molecular formula

C12H8Cl6

Molar mass 364.91 g mol−1

Melting point

104 °C

Vapor pressure 7.5 × 10−5 mmHg @ 20oC

Solubility in water

0.027 mg/L

Laxmi Pande et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 5, Issue No. 2, 277 - 281

ISSN: 2230-7818 @ 2011 http://www.ijaest.iserp.org. All rights Reserved. Page 280

IJAEST

Deildrin:

Fig. 4 Structure of Deildrin[11]

Table 11: Properties of Deildrin[11]

Properties

Molecular formula C12H8Cl6O

Molar mass 380.91 g mol−1

Density 1.75 g/cm³

Melting point

176-177 °C

Boiling point 385 °C Solid Product / Coke: The proximate analysis of Coke is shown in Table 12

Table 12. Proximate analysis of Coke

Sample Coke Moisture % 2-4.5 Ash % 19-25 Volatile Matter %

4-12

Fixed Carbon%

65-75

From the above mentioned values the average calorific value of coke was found to be 6230 kcal/kg[12]. Energy potential of biodegradable waste for a city of 1000 TPD production would be = 0.012 x NCV x W x Z= 0.012 x 6230 x 1000 x .15 = 11.214 MW(Mega Watt) per day. This accounts to very large amount of energy. If the waste is left untreated lots and lots of energy is lost. This technology helps in recovering this energy from waste.

Conclusion : The process utilizes all the waste and converts it into a useful liquid product having fertilizer, pesticidal, insecticidal properties along with coke as a solid product. If 1000 tonnes of Biodegradable waste is treated by this process, about 750 tonnes of Liquid Fertilizer and 150 tonnes of coke having energy potential of 12 MW can be obtained. Remaining is gaseous product which can further be used as fertilizer after passing through water.

REFERENCES

[1] Seema U,Anju S.Energy recovery in solid waste management through CDM in India and other countries.Journal of Resources, Conservation and Recycling 54(2010)630-640. Elsevier.

[2] Singhal S, Pandey P. TERI 2001. Solid waste management in India:status and future directions. TERI Information Monitor on Environmental Science 2001;6(1):1-4

[3] CPCB report 2004 [4] Status of solid waste generation, collection, treatment and disposal in

Indian cities, www.indiastat.com [5] S. Gupta et al.Solid waste management in India: options and

opportunities. Journal of Resources, conservation and recycling 24(1998) 137-154. Elsevier

[6] International Energy Agency (IEA), Key Energy Statistics 2007, http://www.iea.org/textbase/nppdf/free/2007/Key_Stats_2007.pdf

[7] J.Parikh,K.Parikh.India's energy needs and low carbon options, Energy (2011) 1-9. Elsevier

[8] Integrated Energy Policy, Planning Commision,2006,http://planningcommission.nic.in/reports/genrep/rep_intengy.pdf.

[9] Aldrin properties, wikipedia,http://en.wikipedia.org/wiki/Aldrin [10] IUPAC Global availability of information on agrochemical

http://sitem.herts.ac.uk/aeru/iupac/1661.htm [11] Deildrin, Wikipedia, http://en.wikipedia.org/wiki/Dieldrin [12] Calculation of calorific value,

http://www.scribd.com/doc/28046767/Calorific-Values-and-Proximate-Analysis-Of

Laxmi Pande et al. / (IJAEST) INTERNATIONAL JOURNAL OF ADVANCED ENGINEERING SCIENCES AND TECHNOLOGIES Vol No. 5, Issue No. 2, 277 - 281

ISSN: 2230-7818 @ 2011 http://www.ijaest.iserp.org. All rights Reserved. Page 281

IJAEST