New sensor based on pH effect of denitrification process

By observing the acid/base addition rate of a pH controller that centrals the pH in a sample of activated sludge mixed liquor at a set point, the proton dynamics of the reactions taking place in the sample can be monitored. Using this technique, the progress of the denitrification reaction car! be monitored, and. the amount of carbon required for the complete denitrification of the nitrate present in the sample can be determined. A new sensor based on this principle is able to measure on-line the nitrate concentration, the denitrification capacity, and the denitrification stoichiometry without the need for any sample pretreatment. A prototype has successfully been implemented on a full-scale wastewater-treatment plant to automatically control the dosage of an external carbon source

Sensors for Nitrogen Removal Monitoring in Wastewater Treatment

An overview of sensors and techniques for monitoring of nitrogen removal processes is presented. Some recent evolutions in this area are discussed in detail. The overview is not limited to a description of sensors for the on-line collection of ammonium, nitrate and nitrite concentration data but also covers sensors and techniques that can be used to measure nitrification and denitrification activities of activated sludge. Sensors were subdivided into three categories: direct probes (DO, pH, ORP), indirect probes (e.g. on-line NH 4 + and NO 3 - analyzers) and biosensors (e.g. RODTOX, NITROX, DECADOS, BRAM, ...). Finally, the application of activity measurements for influent nitrification toxicity monitoring is discussed, both in technical and cost/benefit terms. 1. Introduction Biological nitrogen removal is nowadays one of the most important and most intensively studied wastewater treatment processes. The growing attention for biological nitrogen removal was favored by the more stri..

Chlorine-Susceptible and Chlorine-Resistant Type 021N Bacteria Occurring in Bulking Activated Sludges

Two filamentous bacteria causing bulking in two activated sludges were examined. Investigations using morphological features, staining techniques, and fluorescent in situ hybridization identified both filaments as type 021N. However, an examination of the effect of chlorine on the sludges revealed a chlorine-susceptible type 021N in one sludge and a chlorine-resistant type 021N in the other

Can we decode the messages of activated sludge through the respirograms?

Wastewater contains varieties of carbonaceous and nitrogenous compounds that undergo complicated biodegradation process in wastewater treatment plants. How these different compounds are degraded by activated sludge in aerobic conditions is still a mystery. Researchers have been trying to interpret it using the oxygen uptake rate (OUR) derived from the respirograms of respective substrates. Several models have been proposed to interpret the substrate removal mechanisms using the experimental observations. Have we succeeded in understanding the messages by activated sludge correctly using these models? In this paper, the distinctive nature of the respirograms when activated sludge is fed with different substrates and the biokinetic models that have been developed to explain the substrate removal mechanisms using derived OUR profiles are reviewed. In addition, a sensitivity study was conducted on the recently evolved simultaneous storage and growth model to investigate the influence of key parameters on OUR profiles during the biodegradation process