Nutrient recovery from domestic wastewater using a UASB-duckweed ponds system

• Published in: Bioresource technology 2007-03, Vol.98 (4), p.798-807
• Main Authors: El-Shafai, Saber A., El-Gohary, Fatma A., Nasr, Fayza A., Peter van der Steen, N., Gijzen, Huub J.
• Format: Article
• Language: English
• Subjects: Ammonia; Applied sciences; Biological and medical sciences; Bioreactors; Biotechnology; Duckweed; Enterobacteriaceae - isolation & purification; Exact sciences and technology; Faecal coliform; Freshwater; Fundamental and applied biological sciences. Psychology; Methods. Procedures. Technologies; Plants - metabolism; Pollution; Production; Treatment; UASB; Various methods and equipments; Wastewater; Wastewaters; Water - chemistry; Water Pollutants; Water treatment and pollution
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2006.03.011

The pilot-scale wastewater treatment system used in this study comprised a 40-l UASB reactor (6-h HRT) followed by three duckweed ponds in series (total HRT 15 days). During the warm season, the treatment system achieved removal values of 93%, 96% and 91% for COD, BOD and TSS, respectively. Residual values of ammonia, TKN and total phosphorus were 0.41 mg N/l, 4.4 mg N/l and 1.11 mg P/l, with removal efficiencies of 98%, 85% and 78%, respectively. The system achieved 99.998% faecal coliform removal during the warm season with final effluent containing 4 × 10 3 cfu/100 ml. During the winter, the system was efficient in removing COD, BOD and TSS but not nutrients. The system was deficient in the removal of faecal coliforms during the winter, producing effluent with 4.7 × 10 5 cfu/100 ml. During the warm season, the N removal consisted of 80% by plant uptake, 5% by sedimentation and 15% unaccounted for. A duckweed production rate of 33 t dry matter per hectare per 8 months was achieved.