Large-scale freshwater microalgal biomass production for fuel and fertilizer. Final report, October 1, 1977--September 30, 1978

Technical Report · Mon Dec 18 04:00:00 EST 1978

DOI:https://doi.org/10.2172/6084461· OSTI ID:6084461

Benemann, J. R.; Weissman, J. C.; Koopman, B. L.; Eisenberg, D. M.; Goebel, R. P.; Oswald, W. J.

Cultivation technology of microalgae for solar energy conversion was investigated. The key aspects studied were maintenance of a stable high-productivity culture and the development of low-cost harvesting technologies. An engineering-economic feasibility analysis indicates that the production of microalgal biomass for chemicals and fuels may be feasible at favorable locations if a simple bioflocculation-settling harvesting process can be developed. A series of experiments was carried out with small-scale (12 sq m) ponds using sewage as the substrate. Detention time was found to be the key operational factor and its optimization was studied in a series of experiments which demonstrated that the algal colony size was affected by changes in detention time. A batch-settling process was investigated for harvesting and the conditions determined which induced rapid flocculation. Detention time and mixing were found to be important factors in promoting a bioflocculating culture. Algal separation was also carried out with a 32,000-liter fill and draw settling tank. Removal efficiencies exceeded 90% for both chlorophyll and suspended solids. Additional experiments carried out under this project were the anaerobic digestion of microalgae harvested from the pilot ponds. Nitrogen-fixing blue-green algae were cultivated on synthetic media with carbon dioxide-enriched air. The main algae used were Anabaenopsis. Temperature was a key factor in its growth and productivities were relatively low; even at 25/sup 0/C, only about 6 to 8 g/sq m/day during the spring were observed. Regrowth of algae on the mixed digester effluents diluted with tap water was carried out in 12 sq m growth ponds with or without carbide addition. Production of fuels from sewage-grown algae was demonstrated to be of near-term practical potential. Significant progress has been made in decreasing costs of microalgal biomass through the harvesting process of bioflocculation-settling.

• Research Organization: California Univ., Richmond (USA). Sanitary Engineering Research Lab.
• OSTI ID: 6084461
• Report Number(s): SAN-0034-1
• Country of Publication: United States
• Language: English

Related Subjects

09 BIOMASS FUELS
090122 -- Hydrocarbon Fuels-- Preparation from Wastes or Biomass-- (1976-1989)
140504* -- Solar Energy Conversion-- Biomass Production & Conversion-- (-1989)
ALGAE
ANAEROBIC DIGESTION
BENCH-SCALE EXPERIMENTS
BIOCONVERSION
CHEMICAL REACTORS
CONVERSION
CULTIVATION
DIGESTION
ENERGY CONVERSION
FLOCCULATION
FUNCTIONAL MODELS
HARVESTING
MANAGEMENT
PILOT PLANTS
PLANTS
PONDS
PRECIPITATION
PROCESSING
PRODUCTIVITY
SEPARATION PROCESSES
SEWAGE
SOLAR ENERGY CONVERSION
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
WASTE MANAGEMENT
WASTE PROCESSING
WASTES