Organic Waste Recycling

120 Organic waste recycling: technology and management

Figure 3.15 Temperature during sludge composting by the BARC system (Shuval et al.
1981)

Benedict et al. (1986) reported that with the operation capacity of 450 wet
tons/day of sludge, the area required for conventional windrow composting of
the Los Angeles, USA, and facility was about 20 ha. However, this total area
included those used for storages of bulking agents, finished compost and
equipment, and for research area; so the operating area for composting was
about 15 ha or 0.03 ha for composting of 1 ton/day of wet sludge.

The DANO System

A schematic diagram of a typical DANO plant manufactured for solid waste
composting is shown in Figure 3.17. It includes storage hoppers, rotary screens
and magnetic separators to separate out non-compostable materials. Materials to
be composted are fed into the "DANO bio-stabilizer", a cylindrical chamber,
tilted slightly from the horizontal, usually about 3 - 4 m in diameter and varying
from 25 to 30 m in length according to the quantity of the feeding materials. The
cylinder rotates at up to 1 revolution per minute (rpm) and air is supplied by
fans at a low pressure, through longitudinal ducts, each having several injector
nozzles. The above conditions enhance effective aerobic decomposition of the
organic matters in the cylinder in which temperatures of 60°C and over are
developed inside. The steam and waste gases are exhausted through extractor

Rainfall events

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Mean

Min.

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