Introduction

Whole Systems Approach to Ecological Design

Appropriate Technology: Water

Organic Agriculture and Local Food

Appropriate Technology: Energy

Green Building & Retrofitting

Sub-Surface Flow Constructed Wetlands

Constructed wetlands technology is a well-proven, natural systems approach for treating sewage.  The biological processes that take place in the wetland include aerobic digestion of organic matter (BOD), plant uptake of nutrients, some nitrification of ammonia and denitrification of nitrate.  The amount of nitrogen and phosphorus uptake in the wetland by plants is minimal.  Phosphorus removal is typically through precipitation with soil cations (Ca2+, Al3+, or Mg2+) or adsorption onto soil particles (Markantonatos et al. 1996).  Wetlands also improve water clarity through the reduction of TSS.   They have the capability to reduce pathogens and priority pollutants.

Sewage treatment constructed wetlands have been widely researched and applied in the US and Europe.  The design parameters have been determined from many hundreds of test projects, including work carried out by the US Army Corps of Engineers, the Tennessee Valley Authority, the Water Research Council in UK, Southampton and Middlesex Universities in UK, the Department of Civil Engineering at UC Davis in California and many other universities and professional engineering firms.

Each region will have its own standards for re-use of treated effluent. 

• Septic Tanks
• Future Optional Vertical Flow Reed Bed to Treat Septage
• Sub-Surface Flow Constructed Wetlands
• Sizing of Wetlands for Sewage Treatment Following Pre-Treatment in Septic Tanks

Regulatory guide for safe use of wastewater, published by the World Health Organisation (WHO) and the United Nations Environment Programme (UNEP)