Utilization of fixed film media in BNR activated sludge systems

The performance of fibrous biomass support media (Ringlace) and porous spongelike biomass support media (Captor) was evaluated for enhanced nitrification and denitrification in a pilot-scale Virginia Initiative Project (VIP) biological nutrient removal (BNR) process. Four separate pilot-scale treatment trains were constructed and operated during this research. Three of the four treatment trains were operated with fixed film media (Ringlace/Captor) incorporated in the aerobic zone of the system and are referred to as the Integrated Fixed Film Activated Sludge (IFAS) systems. A fourth treatment train (Control train) was operated without any fixed film media. All experiments in this research were performed using domestic wastewater from Blacksburg, Virginia, and the Virginia Tech campus. Enhanced nitrification was observed in the IFAS system containing porous biomass support media (Captor) that was freely suspended in the mixed liquor of the aerobic zone. Near-complete nitrification was observed in the IFAS system containing Captor media even at total suspended growth MCRTs as low as 5.6 days and a 12°C liquid temperature. Significantly higher nitrification rates were observed in the IFAS system containing Captor media compared to both the IFAS system containing Ringlace media and the control train. However, there was less denitrification in the aerobic zone of the IFAS systems containing Captor media compared to the Ringlace media systems. Enhanced nitrification could not be statistically shown in the IFAS system containing Ringlace media. The overall nitrification rates in the Ringlace media system were about the same as the control train for the MCRTs and temperatures used during this research. However, a significantly greater amount of denitrification was observed in the aerobic zone of the IFAS system containing Ringlace media compared to both the IFAS system containing Captor media and the control system. Microscopic examination of the growth on the fixed film media (Ringlace and Captor) showed that red worms always grew on the Ringlace media, and were detrimental to performance on at least one occasion. Methods for controlling the worms were developed and applied successfully. During certain operating phases, lower sludge productions and observed sludge yields were measured in the IFAS system containing Ringlace media. However, a Statistical difference could not be calculated between the sludge production in the Ringlace media system and the control system. Lower sludge production and observed sludge yield were also observed in the IFAS system containing Captor media, but only two data points were available and a Statistical t-test analysis was not possible.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Environmental Planning

Department dc:contributor.department

Environmental Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1994

Author dc:creator

• Mitta, Pramod R.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Dc Identifier Other

etd-03302010-020644

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/41878