Organic Waste Recycling

Algal production 229

Figure 5.6 High-rate algal pond at Royal Chitrlada Palace, Bangkok, Thailand

Table 5.2 Conversion factors for the most commonly used units of irradiance

Units gcal/(cm^2 - day) watt/m

2

(or joule/(m^2 -sec))

Btu/(ft^2 -hr)

gcal/(cm^2 -day)

watt/m^2 (or joule/(m^2 -sec))

Btu/(ft^2 -hr)

1

2.06

6.51

0.485

1

3.155

0.154

0.317

1

The engineering factors that can be controlled in the design and operation of
HRAP are described below.

Nutrients

Algae utilize ammonia as the principal source of nitrogen with which to build
their proteinaceous cell material by photosynthetic reaction (Equation 2.6). At
moderately long HRT of 3 days or 4 days when temperature and light are
optimum, almost all the ammonia nitrogen appears in the form of algal cell
material (Oswald and Gotaas 1955). The nitrogen content of a waste material
places an upper limit on the concentration of algal cells to be developed from it.