AN INTEGRATED HIGH RATE POND-ALGAE HARVESTING SYSTEM

SUMMARY A high rate pond-algae harvesting system is proposed, and is compared with a conventional secondary treatment-nutrient removal system. Experimental work supported by the Department of Environment of the Australian Government was conducted by Caldwell Connell Engineers using a 0.28 ha high rate pond and pilot algae harvesting machine of the paper precoated belt filter type. The algae are separated from the precoat and dewatered to yield a high protein concentrate for livestock or fowl, and the precoat is recycled to provide a fresh filter medium. Comparative economic evaluation of the proposed and conventional systems indicate about the same total annual cost including capital recovery. When benefits from sale of the algal product are included, net annual costs of the proposed system are about three-fourths of the conventional system. Non-economic benefits of the proposed system include better resource utilisation and lower total energy inputs and environmental impacts when alternative protein production is considered.