The safe disposal of on-site wastewater is essential for the protection of both groundwater and surface water resources in Ireland. This project reports the results from field trials carried out on three separate sites investigating the attenuation of chemical and microbiological pollutants in domestic wastewater through relatively fast percolating subsoil and also through reed bed treatment systems. In addition, the distribution performance of several different devices designed to split the on-site effluent evenly across the percolation areas was evaluated. Two sites with single houses were chosen with relatively fast percolating subsoil conditions, Site A in County Kildare with T-value of 3.7 and Site B in County Wicklow with T-value of 4.5. The on-site wastewater effluent was treated by a septic tank on Site A and secondary treatment RBC package plant on Site B and then the respective effluents split into two whereby half discharged into a standard percolation area on each site and the other half discharged to horizontal subsurface treatment reed beds. Samples of the respective effluents percolating through the subsoil were collected at different depths beneath the percolation areas for more than two year trial periods as well as monitoring the treatment performance of the reed beds alongside. A third site, Site C in Wexford, was also monitored to investigate the performance of packaged reed bed modules receiving secondary treated effluent. The results showed that higher permeability subsoil acted to reduce the biomat lengths and thus increase the areal effluent loading rate on the percolation areas. The effluent in the trenches receiving septic tank effluent was spread over a biomat length of roughly 10 m compared to the biomats in the percolation trenches receiving package plant secondary treated effluent which were considerably shorter and did not extend beyond 0.5 m. In general, however, the septic tank and percolation system provided a comparable treatment performance with respect to groundwater protection to the packaged secondary treatment system with the exception of nitrogen and viral indicators which underwent enhanced attenuation in the subsoil receiving septic tank effluent. The use of three different bacteriophage tracers (MS2, φX174, PR772) on the sites indicated that enteric viruses in on-site wastewater effluent are likely to be totally removed after a depth of 0.95 m of unsaturated subsoil underneath trenches receiving septic tank effluent. Some phage concentrations were still detected at this depth beneath percolation trenches receiving secondary treated effluent due to the much higher hydraulic loading - a result of muted biomat development. Although 0.95 m of unsaturated subsoil beneath the percolation pipes significantly reduced the enteric bacteria in both types of on-site effluent, there were isolated incidences of low concentrations of E. coli found in the subsoil on both sites at this depth. The horizontal flow subsurface reed bed receiving septic tank effluent was effective at reducing organic, suspended solids and bacteriological loads but not nutrients or the indicator viruses. The reed bed also acted to slightly enhance the hydraulic loading over the course of a year in an Irish climate. Equally, the tertiary treatment reed beds on Sites B and C achieved further polishing of the secondary effluent in terms of organics and enteric bacteria and some removal of nutrient loads. The microbiological quality of the final effluent however, still contained significant numbers of human enteric bacteria and high levels of phosphorus and the beds did not act to attenuate the bacteriophage indicator organisms to any significant extent. Finally, the investigation into distribution devices currently available in Ireland showed that they did not distribute the effluent effectively under real wastewater loading conditions from single houses. The on-site results suggested that the uneven deposition and biofilm growth were responsible for erratic distribution and therefore the long-term performance and sustainability of such devices is questionable for such a function where regular maintenance is rarely carried out by house owners. However, a low-head gravity distribution device has been designed during the project which proved to operate effectively under such low intermittent flow rates of varying effluent quality. Finally the wastewater generation in the three sites was much lower than the EPA guidance value of 180 litres per capita per day: a value of 150 L c-1 d-1 would seem to be a more reasonable design figure.

Go back to top of page Top

Go back to top of page Top

Please Read Carefully Before Downloading

It is important for the EPA and the Environmental Research Community to know that the data and information products we distribute are useful to the user community we support. One way of doing this is by tracking the use of data and information in publications. Parts of or all of the datasets, data, or digital information products available here can be freely downloaded for further use in scientific applications under the condition that the source will be properly quoted in published papers, journals, websites, presentations, books, etc. Whenever possible the EPA strongly urge you to cite the use of these data, information, and web resources in the reference section of your publications. For convenience an automatically generated citation is available below which can be used immediately for citation purposes.

EPA SAFER Data Download Disclaimer: Before downloading any of the data or information objects below you are kindly asked to read the data download disclaimer Read Disclaimer (Opens in New Window). Downloading data or information objects from SAFER-Data indicates an acceptance of the data download disclaimer and the conditions outlined within it.

Suggested Citation Information

The information supplied in the table below should be provided with all citations to this electronic resource. You are requested to format each of the fields below as required by the specific bibliographical style you are using.

An example of this citation in proper usage:

Gill, L. Johnston, P. Misstear, B. O'Luanaigh, N. Patel, T.   "On-site wastewater treatment: investigation of rapid percolating subsoils, reed beds and effluent distribution". Associated datasets and digitial information objects connected to this resource are available at: Secure Archive For Environmental Research Data (SAFER) managed by Environmental Protection Agency Ireland https://eparesearch.epa.ie/safer/resource?id=7cd68383-a2fd-102c-9c91-0a68ec663af0 (Last Accessed: 2023-05-28)

Permalink

Go back to top of page Top

SAFER-Data Display URL	https://eparesearch.epa.ie/safer/iso19115/display?isoID=117
Resource Keywords	Reed beds, percolation, subsoils, effluent, distribution devices, viruses, septic tanks, nitrogen, phosphorus
EPA/ERTDI/STRIVE Project Code	2005-MS-15
EPA/ERTDI/STRIVE Project Theme	Water Quality
Resource Availability:	Public-Open
Limitations on the use of this Resource	Attachments (if any) connected to this resource can be used in journal article or other means of publication provided the original authors are informed of this usage and an appropriate acknowledgement or citation is included within the published article. The EPA advise that this acknowledgement should take one of the following forms dependent upon how heavily the published work relates to the downloaded report: * Co-Authorship(s) for the original author(s)* Written acknowledgement within the body of the article* Written acknowledgement by means of the inclusion of a bibliography entry which clearly cites the original authors. The EPA as a/the primary funder of the research should be acknowledged.
Number of Attached Files (Publicly and Openly Available for Download):	10
Project Start Date	Friday 1st April 2005 (01-04-2005)
Earliest Recorded Date within any attached datasets or digital objects	Monday 10th April 2006 (10-04-2006)
Most Recent Recorded Date within any attached datasets or digital objects	Friday 13th June 2008 (13-06-2008)
Published on SAFER	Friday 5th June 2009 (05-06-2009)
Date of Last Edit	Thursday 26th November 2009 at 08:30:04 (26-11-2009)
Datasets or Files Updated On	Thursday 26th November 2009 at 08:30:04 (26-11-2009)

Go back to top of page Top

Description of Geographical Characteristics of This Project or Dataset
The project investigated three seperate sites consisting of a single house with on-site wastewater treatment system: (1) Kilrainy, Co. Kildare (2) Redcross, Co. Wicklow (3) Riverchapel, Co. Wexford. See bounding boxes below for a map of the locations.

Go back to top of page Top

In this section some supplementary information about this resource is outlined. Lineage information helps us to understand why this project was carried out, what policy or research requirements did it fulfil, etc. Lineage is important in understanding the rationale behind the carrying out of a project or the collection of a specific dataset etc. Links to web sites, applications, papers, etc are outlined to provide you with additional information or supplementary reading about the project or dataset

Any links supplied by the resource owner are stored such that they will open in a new window. Following such a link may lead to a 3rd party website over which EPA has no control in regards to contents or suitability.

Go back to top of page Top

The following is a list of projects, datasets, and resources on SAFER-Data from which users downloaded attachments from soon after downloading attachments from this resource On-site wastewater treatment: investigation of rapid percolating subsoils, reed beds and effluent distribution. You can view the full description for projects, datasets, and resources by using the links supplied.

• Environmental Technology: Development of an Alum Sludge-Based Constructed Wetland System for Improving Organic Matter and Nutrients Removal in High-Strength Wastewater View Full Metadata Description
• Present and Future Technology for the Treatment of Sewage Sludge in Ireland View Full Metadata Description
• Soil Geochemical Atlas of Ireland View Full Metadata Description
• Water Quality characteristics of road runoff View Full Metadata Description
• Water Framework Directive: Recharge and Groundwater Vulnerability View Full Metadata Description

Go back to top of page Top