High rate algal pond systems for low-energy wastewater treatment, nutrient recovery and energy production

Abstract

High rate algal pond (HRAP) systems provide opportunities for low-energy wastewater treatment and energy recovery from wastewater solids, as well as biofuel production from the harvested algal biomass. The wastewater is pretreated using covered anaerobic ponds or gravity settlers and covered digester ponds which remove and digest the wastewater solids. The effluent is then treated in shallow gently mixed HRAP which efficiently breakdown the dissolved organic matter. The algae assimilate wastewater nutrients to provide both secondary and partial tertiary-level treatment. HRAP also provide more efficient natural disinfection. HRAP performance can be further enhanced by bubbling CO 2 into the pond during the day to promote algal growth when it is often carbon-limited. This paper discusses the design and operation and performance of HRAP systems and their application for economical, low-energy upgrade of conventional wastewater treatment ponds combined with energy recovery and biofuel production.

Oxidation pond for municipal wastewater treatment

“…Biogas is formed either during anaerobic digestion of organic compounds or the reduction of carbon dioxide and hydrogen (El-Fadel and Massoud 2001). As a viable energy option, it has been seen as being ideal for electricity generation in a wastewater treatment plant as natural gas, provided that it has undergone several treatment processes (Craggs et al 2014), or for heat and power (NIWA 2008). If biogas is not recovered for energy, it can be flared off or transitioned into an aerobic pond if a multiple pond system exists (NIWA 2008).…”

Enhancing microalgal photosynthesis and productivity in wastewater treatment high rate algal ponds for biofuel production

“…Conventional facultative wastewater pond systems currently used worldwide are costeffective and require little maintenance (Craggs et al 2014). While these ponds have generally performed well in terms of wastewater organic solids removal (BOD removal), the removal of nutrients and disinfection are highly inconsistent and therefore unlikely to meet more stringent regulations starting to be applied to discharge consents (Craggs et al 2014).…”

A review of potential methods for zooplankton control in wastewater treatment High Rate Algal Ponds and algal production raceways

“…1), and can be up to a few hectares in area. Such ponds are able to provide economical and efficient near tertiary-level WW treatment with the nutrients recovered as algal biomass [2,3]. HRAPs are considered to be effective reactors to reclaim water, nutrients and energy from organic wastewaters [4][5][6][7].…”