What are RI Towns Doing?
Block Island
South Kingstown

The BIGHP Project

RIWIS (Rhode Island Wastewater Information System)

Onsite Systems Basics
Onsite treatment systems
Property owner's guide

Wastewater Manager's Toolkit
Creating a management plan
Drafting an ordinance
Developing treatment standards
Funding and staffing a program
Getting the message out
Tracking inspections
Achieving results

Onsite System Research and Assessment
Demonstration systems
Soil suitability
Using GIS for evaluation
Water quality monitoring

Training and technical support

This website is under construction.

Please check back soon for more complete information!

Treatment Technology: Trickling Filter
Trickling filters provide aerobic treatment of wastewater. Wastewater is generally pumped from a recirculation tank or compartment, dispersed over a media bed, and allowed to drain back into the tank. The wastewater is aerated as it flows through the media bed, which may consist of a variety of media such as polystyrene beads, rigid plastics, or tire chips. A trickling filter uses filtration, adsorption, and assimilation for removal of contaminants from wastewater. Wastewater should flow in a thin film over the media to allow time for treatment.
A treatment train containing a trickling filter
In the example system to the right, wastewater flows by gravity through a building sewer (A) from the house into a septic tank (B) where solids separation occurs. Wastewater then flows from the septic tank into the trickling filter (C), where four pumps are located. The first pump doses wastewater to the top of media pillows containing polystyrene beads. Wastewater trickles through the media and flows by gravity back into the sump area of the tank. This recirculation process will reoccur several more times. A second pump transfer some effluent to the head works of the septic tank for denitrification (D), and a third pump transfers accumulated sludge to the inlet of the septic tank (E).
Treated final effluent is pressure dosed by a fourth pump to a bottomless sand filter (F) for final dispersal and treatment.The effluent is dispersed onto and filters through specific sand media in the bottomless sand filter before it reaches the shallow surface soils where further nutrient removal and pathogen reduction may occur. A programmable logic control is used to control and time all dosing events.
Treatment performance observed for trickling filters in RI
% TN Reduction
Fecal Coliform
Coming Soon!
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For more information on textile filters:
Web Links: This type of technology is designed and manufactured by several companies. For more information, please see the vendor websites:
SeptiTech: www.septitech.com


Copyright 2006 URI Water Quality Program