Impacts of chemical root treatment on sludge quality

Tarannom Rohani

Frequent root intrusions in urban sewer network and their hazardous consequences have motivated Water Corporation’s asset managers overlooking the operational sewer network to seek alternative tree root mitigation methods. This study aimed at investigating the suitability of chemical root treatment, a proposed alternative to the current high pressure jet pipe cleaning (jet-washing) maintenance practices, with respect to its effects on wastewater treatment plant processes downstream from the sewer network. The product examined here is a foaming combination of two herbicides, metham sodium and dichlobenil, known by the trade name Sanafoam Vaporooter II (SV II). A laboratory experiment was designed to analyse the impact of this product on nitrification and microbial community in activated sludge samples, as well as biosolids and treated wastewater quality. The experiment was a simple replicate of processes at a real wastewater treatment plant at a bench scale. The study further aimed at conducting a financial analysis to compare the costs of jet-washing and chemical treatment in the long term. The experimental results showed no significant negative impact on any of the parameters measured. The observed trend showed, on average, lower levels of ammonium in contaminated samples compared with controls, and all samples showed similar ranges of nitrite, nitrate and bacterial activity. No impact was observed on biosolids or recycled wastewater quality. The financial analysis for sewer pipes in the Perth Metropolitan Area found chemical treatment more affordable than jet-washing by more than 50% over six years. The results from this study may be used to design further laboratory research with more detailed replications of wastewater treatment processes, or it may further inform a field trial of SV II on few problematic pipes in the existing sewer network.

Impacts of chemical root treatment on sludge quality

Files and links (1)

Abstract

Details

Metrics