Distribution and activity of ammonium‐oxidizing bacteria in Nakivubo wastewater channel and wastewater treatment wetland, Uganda

Abstract

The pollution profiles of Nakivubo channel and wetland, and the spatial distribution of ammonium‐oxidizing bacteria and the corresponding ammonium‐oxidation activities along Nakivubo channel and wetland are presented. A set of physico‐chemical and biochemical variables was monitored, and numbers and activity of ammonium‐oxidizing bacteria in the water, sediment and epiphyton were quantified to estimate their influence on the nitrification and nitrogen bioconversions in general, and to determine the factors influencing the distribution of ammonium‐oxidizing bacteria in Nakivubo channel and wetland. Considerable numbers of ammonium‐oxidizing bacteria and ammonium‐oxidation activities were found upstream of Nakivubo channel suggesting that the physico‐chemical conditions were suitable for the survival of nitrifying bacteria. However, the longitudinal decline in numbers and activity of ammonium‐oxidizers was probably due to (1) high biodegradable organic matter input which supported proliferation of heterotrophs, consuming the little available oxygen, (2) hydro‐sedimentary conditions of the channel, (3) die‐off due to presence of toxic and inhibitory chemicals and metal compounds. The removal of biochemical oxygen demand was significantly higher than that of nitrogen indicating lower self‐purification efficiency for nitrogen. A comparison of the ammonium‐oxidation activity of the different phases indicated that epiphytic nitrification was more important than that of sediment and water compartments of the wetland, whereas sediment and suspended nitrifiers were equally important for nitrification upstream of Nakivubo channel.

Soil Microbial Abundances and Enzyme Activities in Different Rhizospheres in an Integrated Vertical Flow Constructed Wetland

“…Different plant species harbor different microbial flora resulting from variation in the quantity and quality of exudates [2,17,23]. So, using microbial parameter to evaluate the performances of plants in CW systems is a crucial step.…”

How water exchange and seasonality affect the eutrophication of Murchison Bay, Lake Victoria

“…This has increased the concerns for the water quality in the bay (Birungi et al, 2007;Bomo et al, 2011;Kyambadde et al, 2006;Mugisha et al, 2007). In the present study, data are presented from both before and after the widening of the channel.…”

Microbial Communities and Nitrogen Transformation in Constructed Wetlands Treating Stormwater Runoff

“…A majority of studies on N transforming microbial community in CWs have been carried out for domestic (Bastviken et al, 2003;Criado and Bécares, 2005;Shipin et al, 2005;Truu et al, 2005;Dong and Sun, 2007;Sawaittayothin and Polprasert, 2007;Tietz et al, 2007;Wu et al, 2013;Fan et al, 2016;Li et al, 2020) or synthetic wastewater (Fan et al, 2013b;He et al, 2018;Liu et al, 2018;Sun et al, 2018;Xia et al, 2020). There are limited studies focussing on microbial community in CWs treating stormwater and the influence of wetland design features on N transforming microbes (Kyambadde et al, 2006;Domingos et al, 2011;Bledsoe et al, 2020). For example, Bledsoe et al (2020) emphasized the importance of microbial controls on biogeochemical processes in stormwater constructed wetlands in order to improve water quality.…”

“…The rhizosphere mosaic characteristic of aerobic and anaerobic zones assist the process of nitrification and denitrification (Zhu et al, 2010). For example, greater numbers of nitrifying bacteria and higher bacterial activity were detected on plant roots compared to the bulk matrix (Kyambadde et al, 2006). The rhizosphere denitrifying bacteria had different community structure from bulk sediment revealed by PCRdenaturing gradient gel electrophoresis (DGGE) of nosZ.…”