ENERGY RECOVERY FROM ABATTOIR :

In India around 15 million cattle and 1 million sheep and goat are slaughtered per year. The waste generated in abattoir include liquid and solid waste which are detrimental to environment. The liquid waste results from the abattoir, process house and rendering plant, whereas solids consists of meat and bone pieces, the gobar from the holding. the paunch content ( semi-digested stomach remains) etc.

Description			Characteristics

			Moisture content (%)	Dry Solids (%)	Volatile Solids (%)

 Droppings 	       	81.0		19.0		78.6
 Rumen & others (Paunch)	87.0		13.0		87.3
 Fat (from grease trap)	52.2		47.8		98.6
 Agro Wastes		60.0		40.0		68.0
 Other wastes		65.0		35.0		91.0

For the digestion of solids like fleshings, pressmud, abbatoir waste, WABIO process of anaerobic digestion is being proposed. Wabio AD process has been developed and patented by M/s Skanska Econet OY. M/s Nestler Ecotec Pvt. Ltd. (NEPL) are the licencees for this process in India. M/s Hydroair Tectonics Pvt. Ltd. has joined hands to provide this technology on turnkey basis for its implementation.

There are variations in the process of Anaerobic Digestion. The Wabio AD process is a wet process with a solids concentration of around 15%. It operates under mesophilic temperature ie. 35o to 37oC. Due to these conditions, operation is easy to control and gives higher output. Other known processes are fixed film reactor and UASB reactor. These are not suitable for higher concentrated solids as it chokes the media and solids settle down faster at the bottom. The only known anaerobic digestion method is of continuous stirred reactor, which is known to handle 6% - 8% solids.

Cost-Benefit Analysis

INPUT

Total waste		=  50 TPD
Total Volatile solids in the waste	= 11.34 TPD
VS degradation rate		=  80%

COST ANANLYSIS :

Annualised capital cost	=  C [ i(1+i)n]
		     	     i(1+i)n – 1
			=  3,50,00,000 [0.145 (1.145)15]
			       [ (1.145)15-1]
			=  Rs. 50,08,560 /-
			  ( C= Capital Cost= Rs. 3,50,00,000/-,
		 	    i=rate of Interest=14.5%,  n=Life of reactor=15 yrs.)

O & M Cost		=  Rs. 40,00,000 /-

Annualised Cost		=  O& M + Annual Capital
			=  Rs. 40,00,000 + Rs. 50,08,560
			=  Rs. 90,08,560 /-

RECOVERY :


Biogas produced is 0.72m3 per kg. Of VS	=  0.72 x 0.8 x 11.34 x 10 m3 
				=  6532 m3 of biogas/day
				=  272.16 m3 of biogas/hr.

Power generated is 2 KWH / m3		=  544 KWH/hr.
biogas used			=  4.50 x 544 x  24 = Rs. 58,786 /- per day

Recovery
For 300 working days,Cost of power	=  Rs. 1,76,35,968 /-  p.a.

Payback period			=  Capital cost / (Recovery  –  Annualised cost)
				=  35000000 / (17635968 – 10370800)
				=  12.28 years.