The recently discovered comammox bacteria have the potential to completely oxidize ammonia to nitrate. These microorganisms are part of the Nitrospira genus and are present in a variety of environments, including biological nutrient removal (BNR) systems. However, the physiological traits within and between comammox and nitrite-oxidizing bacterium (NOB)-like Nitrospira species have not been ana...

The use of high-rate activated sludge (HRAS) reactors for the removal COD in urban wastewater treatment plants (WWTPs) has been investigated because its potential contribution to energy generating WWTPs. A one-year operation period a pilot plant treating effluent primary settler full-scale WWTP was analyzed. HRAS operated without iron salts addition at temperatures between 12 and 28 °C an avera...

This study investigated the fate of nitrogen species, especially organic nitrogen, along the mainstream wastewater treatment processes in four biological nutrient removal (BNR) wastewater treatment plants (WWTPs). It was found that the dissolved organic nitrogen (DON) fraction was as high as 47% of soluble nitrogen (SN) in the low-SN effluent plant, which limited the plant's capability to remov...

This paper deals with control of bulking by chlorination in a laboratory-scale (15l/ d) biological nutrient removal system. Bulking was caused by filamentous organisms characteristic of nutrient removal systems, i.e. Type 0092, Microthrix parvicella and Type 0914. Over a continuous dosing period of 19 d, at 8 mgCl2 /gMLSS.d the diluted sludge volume index (DSVI) decreased from 230 to 48 ml/g. N...

High concentrations of nitrogen compounds, such as ammonia observed in the petrochemical industry, are the major environmental pollutants. Therefore, effective and inexpensive methods are needed for its treatment. Biological treatment of various pollutants is a low cost and biocompatible replacement for current physico-chemical systems. The use of aquatic plants is an effective way to absorb th...

Two sequencing batch reactors, one with the conventional anoxic and aerobic (AO) process and the other with the multiple AO process, were operated to examine characteristics of biological nitrogen removal, especially of the multiple AO process. The long-term operation showed that the total nitrogen removal percentage of the multiple AO reactor was 38.7% higher than that of the AO reactor. In th...