Influence of wastewater treatment on the microbial ecology of a large, temperate river system ? the Danube River

Abstract

In an attempt to assess the influence of tertiary-treated sewage influx on bacterial metabolism in the Danube River, bacterial abundance, ectoenzymatic activity, faecal coliforms, faecal streptococci, chlorophyll a (chl a), concentrations of dissolved (DOC) and total organic carbon (TOC) and inorganic nutrients were measured upstream of the sewage influx and compared with sampling sites downstream . Additional samples were taken near the outlet of the sewage treatment plant . Bacterial abundance as determined by epifluorescence microscopy was compared with plate counts of total heterotrophic bacteria. Significantly higher values were obtained at the stations downstream from the sewage influx only for faecal coliforms and faecal streptococci, for glucuronidase activity and bacterial biovolume . All the other parameters were not significantly different from values obtained at the upstream sampling site . Strong seasonal dependence was detectable for nitrate with high concentrations during the winter ( ;z~ ᗸ50 pM) and low concentrations during summer (. ::100 ttM) . A distinct spring phytoplankton bloom was noticeable in the river reaching chl a concentrations of . : 70 pg 1-1 ; during the remaining seasons chl a concentrations were <ᗸ0 pg 1 -1 . Highly significant correlations were found between faecal coliform counts and glucuronidase activity . C :N :P ratios of 13 .9 :10.7 :1 (for the upstream station) and 11 .7 :9 .ᗸ :1 (for the downstream stations) of dissolved nutrients are rather low indicating severe carbon limitation of bacterioplankton . Based on our results we conclude that the heterotrophic bacterial community is not significantly effected by the input of treated sewage but faecal contamination is readily detectable over a comparatively long reach of 30 km .

Extracellular enzyme activities in benthic cyanobacterial mats: comparison between nutrient- enriched and control sites in marshes ofnorthern Belize

“…Romaní & Marxsen (2002) found higher enzymatic activities of stream biofilms in unshaded sites. Aminopeptidase activity was reported to be enhanced by the release of proteinaceous substances by living or senescent algal cells (Hoch et al 1996), which is a process likely to occur within cyanobacterial mat communities. A positive relationship between chlorophyll a and aminopeptidase activity in stream epilithic biofilms was observed by Ainsworth & Goulder (2000).…”

Faecal contamination of water and sediment in the rivers of the Scheldt drainage network

“…An important increase of faecal coliforms was reported by Servais et al (2007) in the Seine River downstream from the Parisian area. A moderate increase in coliform counts was observed in the Danube River downstream from Vienna (Hoch et al 1996) and large increases downstream from Budapest and Bucarest (Kirschner et al 2009). The importance of such quality decrease is directly related to the ratio of the effluents and the river flow rates and to the FIB concentration in the treated effluent depending on the type of treatment; this ratio is particularly high in the case of the impact of Brussels treated wastewaters on the Zenne River.…”

Relating Watershed Characteristics to Elevated Stream Escherichia coli Levels in Agriculturally Dominated Landscapes: An Iowa Case Study

“…Point source-dischargers, such as wastewater treatment plants, typically use chlorination, UV irradiation, or ozonation to disinfect their effluent. However, increases in bacterial abundance have been observed downstream of wastewater treatment plants [24,25]. Animal Feeding Operations are a significant risk of FIB impairment through three primary sources: accumulated manure in open and unpaved feedlots; manure stored in holding ponds, lagoons, and uncovered stockpiles; and from excess manure and wastewater applied to land [26].…”