Effects of umbrella palms and wastewater depth on wastewater treatment in a subsurface flow constructed wetland

• Published in: Environmental technology 2003-04, Vol.24 (4), p.471-478
• Main Authors: Stecher, M. C., Weaver, R. W.
• Format: Article
• Language: English
• Subjects: Applied sciences; Biological and medical sciences; Biological treatment of waters; Biotechnology; Constructed wetlands; Cyperus - chemistry; Cyperus - growth & development; Ecosystem; Enterobacteriaceae - isolation & purification; Environment and pollution; Exact sciences and technology; Facility Design and Construction; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Methane - analysis; Oxygen - metabolism; Phosphorus - isolation & purification; Phosphorus - metabolism; plants; Pollution; Temperature; Waste Disposal, Fluid - methods; wastewater depth; Wastewaters; Water Movements; Water treatment and pollution
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330309385582

On-site subsurface flow constructed wetlands are designed to provide secondary quality effluent. Plants and wetland volume are considered in their design. There have been no studies, however, comparing wastewater treatment at different wastewater depths, and plant effects in wetlands are not completely understood. Investigations were conducted on these variables using four wetland cells 2.28 m wide by 4.75 m long containing I to 5 cm diameter river rock. Cyperus alternifolius (umbrella palms) were planted in one cell, and side-by-side comparisons were made between the planted and a control cell. Side-by-side comparisons were also made between cells with equal surface areas and different depths. At best, umbrella palms improved effluent 5-day biochemical oxygen demand (BOD 5 ) by 8%, suspended solids by 6 %, and did not improve fecal coliform or P wastewater quality in July. When ambient air temperatures were ≤12°C during December, plants did not improve most treatment parameters. They did, however, significantly improve NH 4 + treatment, even when ambient air temperatures were as low as 8°C. Increasing wastewater depth enhanced fecal coliform die-off but did not reduce effluent BOD 5 , suspended solids, NH 4 + , or P in effluent. Umbrella palms should be considered when maximum NH 4 + reduction is a treatment goal and it is not necessary to reduce other parameters. Surface area was more important to wastewater treatment than depth