Introduction 11yields such as weeds, algae, crops and fish can be used as food or feed for other
higher life forms, including human beings, while treated wastewater is discharged
to irrigated land. The integrated systems that combine several aspects of waste
recycling at small- and large-scale operations have been tested and/or commercially
implemented in both developing and developed countries.
An alternative concept, that has high application potential for unsewered areas,
is decentralised wastewater management. This concept implies the collection,
treatment and disposal or reuse of wastewater from individual, or clusters of
homes, at or near the point of waste generation (for example, a decentralized
system may employ composting toilets to treat feces and other organic solid
wastes, while the wastewater liquids (from bathroom and washing) can be treated
by constructed wetlands). The composted products are used as organic fertilizers,
which effluent of the constructed wetlands can be used for irrigation of crops and
lawns. Some examples of the above systems that have been in successful operation
on a commercial scale are described below.
1.3.1 Kamol Kij Co. Rice Mill Complex and Kirikan Farm,
Thailand (Ullah 1979)
The Rice Mill Complex (area 18 ha) and Kirikan Farm (area 81 ha), owned by the
same company, are located in Pathumthani Province, about 30 km north of
Bangkok. Figure 1.5 shows the recycling of by-products or wastes generated from
the rice milling units which produce about 500 tons per day of parboiled and
polished rice from purchased paddy. Rice husks are burned to produce the energy
needed for parboiling, paddy drying and oil extraction. The husk ash is mixed with
clay to make bricks, and the white ash from the kiln, containing about 95 percent
silica, is sold for use in making insulators and abrasives.
Fine bran from the rice mill is passed to the oil extraction plant to produce crude
vegetable oil about 20 percent in concentration; this crude oil is sold to a vegetable
oil refinery factory to produce edible vegetable oil. The defatted rice bran is used as
animal feed at Kirikan Farm.
The Kirikan Farm, one of the biggest integrated farms in Thailand, maintains
livestock, fish and crops, as shown in Figure 1.6. There are approximately 7,000
ducks, 6,500 chickens and 5,000 pigs being raised there, using feed from the rice
mill defatted bran and other feed components. The farm could sell about 430,000
duck eggs and 1.2 million chicken eggs in a year.