The reasons behind the performance superiority of a high rate algal pond over three facultative ponds in series

• Published in: Water science and technology Vol. 48; no. 2; pp. 269 - 276
• Main Authors: EL HAMOURI, B, RAMI, A, VASEL, J.-L
• Format: Conference Proceeding Journal Article
• Language: English
• Published: London IWA 01-01-2003; IWA Publishing
• Subjects: Algae; Applied sciences; Biodegradation; Biodegradation, Environmental; Biological and medical sciences; Biological treatment of waters; Biotechnology; Chlorophyll; Chlorophyll - analysis; Chlorophyll a; Constants; Environment and pollution; Eukaryota; Exact sciences and technology; Facility Design and Construction; Fundamental and applied biological sciences. Psychology; General purification processes; Hydraulics; Hydrodynamics; Industrial applications and implications. Economical aspects; Kinetics; Load distribution; Loading rate; Oxygen - analysis; Oxygen - chemistry; Pollutants; Pollution; Ponds; Rate constants; Removal; Retention; Tracers; Waste Disposal, Fluid - methods; Wastewaters; Water treatment; Water treatment and pollution
• ISBN: 9781843394464; 1843394464
• ISSN: 0273-1223; 1996-9732
• DOI: 10.2166/wst.2003.0130

Results from a tracer study were used to determine and to compare actual and standard (k(20 degrees C)) first order reaction rate constants for COD removal in a High Rate Algal Pond (HRAP) and in 3 facultative ponds (FP) in series. An annual average k(20 degreesC) of 0.123 day(-1) was found for the HRAP while the values of 0.097, 0.025 and 0.003 d(-1) were found for facultative ponds 1, 2 and 3 respectively. Also, comparing nominal and tracer study hydraulic retention times showed large differences for the FP but not for the HRAP indicating that the former were suffering from severe short-circuiting. Loading rate within the range of operation exhibited a positive correlation with k(20 degrees C) for the HRAP but did not show such a relationship for any of the FP. Optimal chlorophyll-a concentration was found to be 3 mg/l for the HRAP and only 1.1 mg/l for the FP. Pollutant specific removal rates (SRR), that translate the hydrodynamic efficiency and the rate of COD biodegradation into pond performance per m2 and per day were calculated. They show that the adoption of the HRAP in place of a series of 3 FP reduces the net land area requirement (LAR) by at least 40%.