Presentation Title

Greener DEWATS: Duckweed as a Natural Polishing Step for Anaerobic Wastewater Treatment Plants

Start Date

November 2016

End Date

November 2016

Location

HUB 302-#99

Type of Presentation

Poster

Abstract

Decentralized Wastewater Anaerobic Treatment Systems (DEWATS), such as the anaerobic baffled reactor (ABR), are increasingly being installed in rapidly growing urban areas, like South Africa, where the provisions of water and sanitation services are challenging. The effluent from anaerobic systems tend to be rich in nitrogen and phosphorus, and recovery of these nutrients is an important goal for sustainable DEWATS. The purpose of this research was to evaluate the use of a floating aquatic angiosperm, such as duckweed, for nutrient recovery and further effluent polishing. A key step in this study was determining where the inclusion of duckweed would best serve the system to allow water to be discharged back into the environment without detrimental effects. Wastewater collected from different points in the DEWATS were made into dilutions from 100% to 25% wastewater (WW), and were inoculated with duckweed. The water was tested for phosphate, turbidity, chemical oxygen demand (COD), total solids and volatile solids over the retention time of two weeks. Daily measurements of pH, electrical conductivity, and temperature were made. Duckweed was harvested and measured for dry biomass. Plant uptake resulted in an average of 93% reduction in turbidity with average final values of 7.02 NTU for 100% WW. COD reduction was present in most cases, and total solids showed an overall trend of increasing while volatile solids showed that of decreasing. The overall results show that the inclusion of duckweed will improve the quality of treated wastewater and will allow further polishing of the quality of wastewater.

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Greener DEWATS: Duckweed as a Natural Polishing Step for Anaerobic Wastewater Treatment Plants

HUB 302-#99

Decentralized Wastewater Anaerobic Treatment Systems (DEWATS), such as the anaerobic baffled reactor (ABR), are increasingly being installed in rapidly growing urban areas, like South Africa, where the provisions of water and sanitation services are challenging. The effluent from anaerobic systems tend to be rich in nitrogen and phosphorus, and recovery of these nutrients is an important goal for sustainable DEWATS. The purpose of this research was to evaluate the use of a floating aquatic angiosperm, such as duckweed, for nutrient recovery and further effluent polishing. A key step in this study was determining where the inclusion of duckweed would best serve the system to allow water to be discharged back into the environment without detrimental effects. Wastewater collected from different points in the DEWATS were made into dilutions from 100% to 25% wastewater (WW), and were inoculated with duckweed. The water was tested for phosphate, turbidity, chemical oxygen demand (COD), total solids and volatile solids over the retention time of two weeks. Daily measurements of pH, electrical conductivity, and temperature were made. Duckweed was harvested and measured for dry biomass. Plant uptake resulted in an average of 93% reduction in turbidity with average final values of 7.02 NTU for 100% WW. COD reduction was present in most cases, and total solids showed an overall trend of increasing while volatile solids showed that of decreasing. The overall results show that the inclusion of duckweed will improve the quality of treated wastewater and will allow further polishing of the quality of wastewater.