Algal ponds

Table 4.3 Output of protein from algal ponds and conventional sources...

In algal pond cultures cell concentrations of 2 g dry wt 1" are possible, corresponding to outputs of 15 g dry wt per square metre per day. What would the protein output of such a system be (as kg protein per hectare per year), assuming the dry algal biomass contains 45% protein (Use a piece of paper to do this calculation and then compare it with ours). 

Algae were selected as the prime focus for an integrated subsystem for PEF because the technology of algal ponds is reasonably well developed and is based on years of experience with ponds for treatment of municipal and industrial wastes. However, algae present some major engineering problems in mass cultivation and harvesting. 

Park, J.B. and Craggs, R.J. (2011) Algal production in wastewater treatment high rate algal ponds for potential biofuel use. Water Sci. Technol., 63 (10), 2403-2410. 

A.N. (2011) Wastewater treatment high rate algal ponds for biofuel production. Bioresour. Technol., 102 (1), 35-42. 

High-rate aerobic algal ponds nitrification Stabilisation carbonaceous BOD removal Carbonaceous BOD removal... 

Yang [85] constructed a mathematical model to simulate the behavior of an open algal pond, particularly with respect to CO2 supply and utilization, taking wastewater as feed, which also provides substrate for aerobic bacteria and nutrients for the algal-bacterial consortium. Figure 14 shows the effect of CO2 fraction and supplied gas... 

Effect of supplied gas flow rate and CO2 fraction on the performance of the algal pond [85]. 

Raceway ponds are popular algal pond systems and are the preferred production system for many of the commercial operations, including Cyanotech Corporation in Hawaii and Earthrise in California, both of which produce Arthrospira (Spirulim), as well as Seambiotic in Israel (Plate 9.1c). Excessive evaporation is a problem in these regions and a minimum depth of at least 15 cm is required to avoid a reduction in flow which can result in light limitation (Tredici, 1999). 

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