504 Organic Waste Recycling: Technology and Management
This environmental policy initiated by the Quebec Province is considered an
effective tool for the municipalities to determine sustainable solutions to manage
their solid wastes with the beneficial results in pollution control, energy
recovery and reduction of greenhouse gas emission to the atmosphere.
10.6.2 Sanguan Wongse Industries Co., Ltd., Nakhorn
Ratchasima province, Thailand. (www.swi.co.th)
The Sanguan Wongse Industries Co., Ltd., located about 200 km northeast of Bangkok
city, Thailand, uses about 4,000 tons/day of fresh cassava roots to produce 1,000 tons/day
of starch and related products for local consumption and exports to several countries
worldwide. The tapioca production processes (see section 2.3.1) generate 9,600 m^3 /day
of wastewater having a COD concentration of 30,000 mg/L.
Figure 10.2 Anaerobic baffled reactors (ABR) covered with plastic sheets for wastewater
treatment and biogas production
As part of its efforts to meet the ISO 9002 standard for quality assurance and
the Thailand brand logo for high quality export certification of the Department of
Export Promotion of Thailand, the company has employed anaerobic baffled
reactors (ABR) to treat 60% of this wastewater volume (Figure 10.2). This reactor
is able to remove more than 90% of the COD input with CH 4 gas production of
70,000 m^3 /day, equivalent to the CH 4 production rate of 0.35 m^3 /kg COD (similar
to the theoretical value as given in section 4.5). The CH 4 gas is fed to a co-
generator to produce boiler steam and electricity for uses in the starch production
processes, resulting in a cost saving of approximately 35,000 Baht (US$ 900) per
day. The remaining 40% of the wastewater together with the ABR effluent are
treated in a series of waste stabilization ponds. The pond effluent, which meets the
Thailand effluent standard (Table 10.6), is discharged to a nearby river.