Organic Waste Recycling

224 Organic waste recycling: technology and management

wastewater treatment. (The term 'high-rate' is commonly used for algal ponds

because algal growth rate in these ponds is several times greater than that

occurring in conventional waste stabilization ponds whose objective is mainly

waste treatment. Details of the high-rate ponds are given in section 5.2.) The

waste-grown algae thus need to be processed further prior to being employed as

human or animal feed. These algae can be used for other purposes as shown in

Figure 5.2 and section 5.4.

CO 2 + NO 3 - + PO 4 3- + H 2 O {CH 2 ONP} + O 2

Figure 5.2 Possible applications of algal mass cultures (from Goldman 1979a;

reproduced by permission of Pergamon Books Ltd)

Photosynthetic reaction
Solar
energy
Algal biomass

O 2

Production

Water

Fertilizers

Extracted commercial

chemicals

Animal protein

supplement

Human protein

supplement

Aquaculture

Treated

wastewater

Solar energy

Nutrients

wastes

chemicals

Methane

energy

Commercial

chemicals

N 2 Fixation

CO 2

Algal

growth

Anaerobic

digestion

Algal

separation