Utilizing heat from rice hull biochar production for steam pasteurization of mushroom fruiting bags

Figures & data

Figure 1. The existing practice of producing biochar from rice hull using the open-type rice hull carbonizer (right).

Figure 2. The use of the CtRH carbonizer in the production of oyster mushrooms within Palayamanan.

Figure 3. The CtRH carbonizer with its cooking attachment.

Figure 4. The steam generating vessel and its accessories.

Figure 5. The complete setup of the MFB pasteurization system utilizing the heat from the CtRH carbonizer.

Table 1. Performance of the prototype steam pasteurization system for MFBs

Parameter	Trial 1	Trial 2	Trial 3	Average
	Sep 23, ‘16	Sep 28, ‘16	Oct 6, ‘16
(1) Rice hull consumption, kg h^−1	11.59	11.92	11.59	11.70
(2) Biochar yield, %	33.40	40.73	30.96	35.03
(3) Contamination, %	0.19	2.50	3.08	1.92
(4) Actual capacity, No. of MFBs	520	560	520	533

Figure 6. Plot of the average temperature (9 locations) of each of the three test trials conducted.

Figure 7. Temperature profile of the ambient air (T1) and of the nine MFBs (T2-T10).

Table 2. Performance of the CtRH carbonizer as source of heat in the pasteurization of MFBs

Parameter	Test run #1	Test run #2	Test run #3	Average
	Sep 23, ‘16	Sep 28, ‘16	Oct 6, ‘16
(1) Generated steam, kg h^−1	4.82	6.24	6.59	5.88
(2) Heat supplied by the carbonizer, MJ	1,096.84	1,023.17	1,130.89	1,083.63
(3) Energy reqmt for pasteurization, kJ MFB^−1	208.82	248.71	282.60	246.71
(4) Thermal Efficiency, %	9.90	13.61	12.99	12.17

Table 3. System’s performance as compared to other reported pasteurization methods

Technology	Pasteurization energy needed per kg mushroom (kJ)
CtRH carbonizer	1,233.55
LPG with solar water heater	946.55*
LPG without solar water heater	2,094.18*

^* Derived values based from the report of Ale and Shrestha (2014).

Table 4. Comparison of fuel parameters between the developed system (carbonizer-generated heat) vs. other sources of heat

Fuel Parameters	Source of heat
	CtRH carbonizer (rice hull)	LPG burner	Wood burner
Heating value of fuel, MJ/kg	15.9 ^1	46 ^2	17 ^3
Thermal Efficiency, %	12.17	55 ^4	12.23 ^5
Amount of fuel consumed per 100 MFBs, kg	12.93	0.97	7.26
Fuel unit cost, Php/kg	1.83	59	5.0
Fuel cost per 100 MFBs	23.66	57.23	36.30
% Savings	–	58.7	34.82
GHG emission from fuel combustion, kg CO2eq/kg fuel	0.100 ^6	3.220 ^6	0.118 ^6
Expected GHG emission per 100 MFBs, kg CO2eq	1.293	3.123	0.857

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² Lee, Oh, and Choi (2009).

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⁴ Pantangi, Mishra, Muthukumar, and Reddy (2011).

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