Bacteria in non-woven textile filters for domestic wastewater treatment

Abstract

The objective of this study was preliminary identification of heterotrophic and ammonia oxidizing bacteria (AOB) cell concentration in the cross-sectional profile of geotextile filters for wastewater treatment. Filters of thicknesses 3.6 and 7.2 mm, made of non-woven textile TS20, were supplied with septic tank effluent and intermittently dosed and filtered under hydrostatic pressure. The cumulative loads of chemical oxygen demand (COD) and total solids were about 1.36 and 1.06 kg/cm2, respectively. The filters under analysis reached a relatively high removal efficiency for organic pollution 70-90% for biochemical oxygen demand (BOD5) and 60-85% for COD. The ammonia nitrogen removal efficiency level proved to be unstable (15-55%). Biomass samples for dry mass identification were taken from two regions: continuously flooded with wastewater and intermittently flooded with wastewater. The culturable heterotrophic bacteria were determined as colony-forming units (CFUs) on microbiological-selective media by means of the plate method. AOB and nitrite oxidizing bacteria (NOB) were examined using the FISH technique. A relatively wide range of heterotrophic bacteria was observed from 7.4×10(5)/cm2 to 3.8×10(6)/cm2 in geotextile layers. The highest concentration of heterotrophic bacteria (3.8×10(6)/cm2) was observed in the first layer of the textile filter. AOB were identified occasionally--about 8-15% of all bacteria colonizing the last filter layer, but occasionally much higher concentrations and ammonia nitrogen efficiency were achieved. Bacteria oxidizing nitrite to nitrate were not observed. The relation of total and organic fraction of biomass to culturable heterotrophic bacteria was also found.

Effect of thickness of textile filter on organic compounds and nutrients removal efficiency at changeable wastewater surface level

“…As was noted in other related experiments (Spychała and Starzyk, 2015) the highest content was observed in the first (wastewater-side) layer and commensurate to filter layer depth, the total solids content decreased. The lowest content was observed in the last (air-side layer).…”

“…Neither nitrites nor nitrates were observed during this study (Spychała and Starzyk, 2015), however these kinds of bacteria were observed during a study made by on TS50 geotextile filters -the NOB number from 1.9 × 10 3 to 1.1 × 10 5 CFU/cm 2 .…”

“…Conditions conducive to ammonium nitrogen oxidation were also confirmed by ammonium oxidizing bacteria identification (Spychała and Starzyk, 2015), using a Nitri-VIT ® gene probe technology set that contains a mixture of oligonucleotide DNA. These DNA probes are complementary to specific 16S rRNA sequences of the common ammonium oxidizing bacteria, as reported by Woznica et al (2010).…”

“…The terms of nitrogen compounds related processes were described and commented in details in Spychała and Starzyk (2015) paper.…”

“…The term and abbreviation: Textile Filter for Wastewater Treatment (TFWT) has been proposed for this type of filters by the authors of this paper since it was developed by them alongside co-development with Błażejewski . These reactors have been already described in relation to performance and biomass-microbial characteristics (Spychała and Starzyk, 2015). It should be noted that filters in the study conducted by were made of other types of geotextile (market names: TS 50 and TC/PP 300).…”