Wastewater treatment Efficiency of Subsoils and Stratified Sand Filters

Wastewater treatment Efficiency of Subsoils and Stratified Sand Filters

In Ireland, wastewater from one third of the population is treated in small-scale independent systems, usually in rural areas where connection to a sewer is deemed to be unfeasible. The most prevalent treatment application is the conventional septic tank system with over 350,000 systems currently installed in Ireland. In situations where septic tank installation is not suitable, mechanically aerated systems can be used which include rotating biological contractors (RBC), biologically aerated flooded filters (BAFF) and sequencing batch reactors (SBR). The recently published EPA guidance manual Treatment Systems for Single Houses determines whether a location is suitable for a septic tank installation by means of a percolation test on the subsoil of the proposed site. Suitable subsoil for septic tank effluent is currently defined as having a T (or P) value within the range 1 to 50. Where suitable subsoils do not exist for a conventional drainage area, the possibility of using a stratified sand filter to treat the effluent has been highlighted. The objective of this research project is to conduct a series of rigorous trials in order to enhance the understanding of the performance of both stratified sand filters and different subsoils for the treatment of typical domestic effluent from septic tanks and other small-scale secondary treatment installations. The project is divided into four phases and will be completed within a 36-month framework: Phase I Initial desk study and site identification (6 months); Phase II Trials at two test sites (septic tank and secondary treatment effluent) on stratified sand filter and subsoil performance (12 months); Phase III Trials at two further sites (septic tank and secondary treatment effluent) on subsoil performance (12 months); Phase IV Collation of results, analyses and final report preparation.

If you want to read more about this project, you can do so at erc.epa.ie.

Environmental Protection Agency 2000-MS-15-M1
Laurence Gill

Keywords: Wastewater; Treatment Systems for Single Houses; Subsoils; Stratified Sand Filters

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