The Belmont Valley integrated algae pond system in retrospect

Abstract

Integrated Algae Pond Systems (IAPS) are a derivation of the Oswald-designed Algal Integrated Wastewater Pond Systems (AIWPS®) and combine the use of anaerobic and aerobic bioprocesses to effect sewage treatment. IAPS technology was introduced to South Africa in 1996 and a pilot plant designed and commissioned at the Belmont Valley WWTW in Grahamstown. The system has been in continual use since implementation, and affords secondarily treated water for reclamation according to its design specifications, which most closely resemble those of the AIWPS Advanced Secondary Process. In this paper IAPS as a municipal sewage treatment technology is re-examined in relation to design and operation, the underpinning biochemistry of nutrient removal by algae is described, and a retrospective is provided on the demonstration system at the Belmont Valley WWTW. In addition to presenting details of the process flow, several shortcomings and/or oversights are highlighted and, in particular, the need for an appropriate tertiary treatment component. However, despite the use of IAPS for sewage treatment in many countries, this technology is still viewed with some scepticism. Thus, a major purpose of this overview is to provide a synthesis of available information on IAPS and an appraisal of its use for municipal sewage treatment.

A Brief Review of Anaerobic Digestion of Algae for Bioenergy

“…Advanced Integrated Wastewater Pond System (AIWPS) or Integrated Algae Pond Systems (IAPS) integrate HRAPs with anaerobic and aerobic biological processes for wastewater treatment. Wastewater initially enters a covered anaerobic pond or advanced facultative pond where organic solids settle and decompose anaerobically producing biogas that is collected by a pond-cover for use as fuel [56,79,86]. Water laden with nutrients then flows to HRAPs where microalgae grow.…”

“…The construction capital costs for an Advanced Pond System are <50%, and operational costs are <20% relative to activated sludge systems but require~50-fold the land area of activated sludge systems for the same Biological Oxygen Demand (BOD) removal, excluding the land area needed to dispose of waste activated sludge [56]. Where land constraints permit AIWPS and IAPS are now utilised globally for the remediation of wastewater [68,79,86,[88][89][90].…”

Efficiency of wastewater treatment by a mixture of sludge and microalgae

“…pH and Electrical conductivity (EC) were measured using a pH meter and conductimeter (HANNA) respectively. [32]. The microalgae sludge systems were set up using an approach similar to that of [36].…”

“…Preliminary results of this collaboration indicated that the sewage sludge from the wastewater treatment plant Grahamstown is not stabilised enough for reuse ,while, the sewage sludge from the wastewater treatment plant in Tiaret, Algeria is stabilised enough to allow for reuse [31]. The algal pond system is present here and has been studied extensively [32] Diatoms, e. Chlorella, f.Closterium, g.Chlamydomonas, h.Pyrobotrys,i. Euglena, j.Actinastrum,k.Dictyosphaerium, l. Blue greens.…”

Note to Editor: Microalgae cultivation for wastewater treatment and biofuel production: a bibliographic overview of past and current trends

“…A few of the recent reviews advocate for mixotrophic cultivation as a means to enhance biomass productivity [52,53,70,71], while the two-stage cultivation, with a luxury consumption stage followed by nitrogen limitation, is recommended for lipid production [58,70,71]. Both nutrient removal [72][73][74][75] and nutrient uptake [32,76,77] are discussed in the context of lipid production.…”