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Biomat development in percolation trenches


A SIM Talk by Jan Knappe will take place before lunch on March 7th,  Room A2-002 . The SIM Talk will consist of a 15 minute presentation followed by discussion.

Speaker: Jan Knappe, Dept. of Mathematics and Statistics, University of Limerick

Topic: Biomat development in percolation trenches

Time: 12.30p.m.  Tuesday March 7

Room A2-002

Short Abstract:     With circa 500,000 septic tank systems currently installed, approximately one third of domestic wastewater generated in Ireland is treated in on-site domestic wastewater treatment systems (DWWTs). DWWTs are most commonly composed of a septic tank and a soil attenuation system for further treatment and effluent dispersal. In the soil, water is cleaned by microbial activity which depends on nutrient cycling but also controls it and, thus, determines whether excess nutrient levels contaminate groundwater or surface runoff and constitute a pollution risk.

Previous research has shown that the development of a microbial biomat which forms along the base and wetted sides of percolation trenches is key to the hydraulic loading and subsequent attenuation of pollutants in the unsaturated zone. The quality of the biomat, therefore, influences the overall pollutant loading to the groundwater. 

Based on experimental studies at field sites effective mathematical models to describe the growth and interaction of soil biomass with nutrients are developed and calibrated. A variety of design alternatives (primary and secondary treated effluent, pumped vs. gravity-fed distribution) is being evaluated to predict the vertical and horizontal extent of wastewater contamination zones.