Background: Algal biofuel production can be made sustainable in partnership with dairy farms, industries and municipal systems for nutrient management requiring waste treatment. Waste streams contain unmined nutrients such as nitrogen, phosphorus, and carbon. The nutrients runoff especially nitrogen and phosphorus pollution can impair water quality of natural water bodies posing environmental threat due to undesirable algae blooms affecting natural aquatic communities. Anaerobic biodigesters can efficiently take care of biochemical oxygen demand to improve water quality but leave behind excess nutrients in the effluent. The excess nutrients can be potentially used for selected algal biomass growth for fuel and co-products.
Methods: This paper reviews the algal biofuel systems that can integrate with biodigesters for sustainable cogeneration of renewable energy forms (liquid biofuels, electricity, and heat) so that the waste effluent from dairy farms, municipal and industrial anaerobic digesters, food and beverage and other industries can be combined with the algal biofuel process to produce additional valued co-products including feedstock for biogas, organic fertilizer, and animal feed for generating additional revenues.
Conclusion: A successful implementation of a system as described will have multifold higher oil yield from non-food algae biomass compared to food sources (e.g. soybean and corn oil) for biofuel; benefit environment by capturing nitrogen and phosphorus from effluents to reduce environmentally harmful runoff affecting the health of natural water bodies, reduce in the fuel emissions especially the oxides of nitrogen in contrast to both diesel and conventional biodiesel, meet environmental protection regulations with reductions in particulate matter and total hydrocarbons; and bring economic benefits from marketable products across the complete supply chain involved at the sites that implement bolt on algal system with waste management systems for cogeneration of energy.