Estimation of Biomass Concentration and Population Dynamics in a Captor® Activated Sludge System

1994 ◽  
Vol 29 (7) ◽  
pp. 149-152 ◽  
Author(s):  
M. P. Reddy ◽  
K. R. Pagilla ◽  
P. R. Senthilnathan ◽  
H. W. Johnson ◽  
P. S. Golla
Keyword(s):  
Population Dynamics ◽  
Activated Sludge ◽  
Microbial Population ◽  
Biomass Concentration ◽  
Activated Sludge Process ◽  
Free Swimming ◽  
Activated Sludge System ◽  
Suspended Growth ◽  
Fixed Film ◽  
The Media

A technique was developed to measure the equivalent MLSS in the fixed film Captor® media-activated sludge process. The technique accounts for the wear in the media as well as unequal wear in different media. The microbial population variations encountered during three years of full scale operation of the Captor® process, at the Moundsville WWTP were recorded. It has been found that fixed film media seem to support predominantly rotifers, followed by free swimming ciliates, and single stalk ciliates. In contrast, the suspended growth activated sludge population contained lower level organisms, mostly free swimming ciliates, followed by stalk ciliates, flagellates, and a few rotifers.

Seasonal change of microbial population and activities in a building wastewater reuse system using a membrane separation activated sludge process

1996 ◽  
Vol 34 (5-6) ◽  
pp. 295-302 ◽  
Author(s):  
Boran Zhang ◽  
Kazuo Yamamoto
Keyword(s):  
Activated Sludge ◽  
Seasonal Change ◽  
Microbial Population ◽  
Membrane Separation ◽  
Wastewater Reuse ◽  
Biomass Concentration ◽  
Plate Count ◽  
Ammonia Oxidizing Bacteria ◽  
Activated Sludge Process ◽  
Reuse System

The seasonal change of microbial population and activities in an existing building wastewater reuse system using membrane separation activated sludge process (MSAS) were investigated, and they were also compared with those in a municipal wastewater treatment plant using conventional activated sludge (CAS) process. The operating conditions of MSAS process, such as sludge retention time, biomass concentration, the ratio of food to microorganism (F/M) and so on, are much different from CAS process. Acridine orange direct count (AODC), plate count of heterotrophic bacteria (HPC), MPN of ammonia oxidizing bacteria (MPNa) and microfauna were measured. In the MSAS process, the AODC and MPNa/HPC were high, but the HPC/AODC was low. This means that the MSAS process tended to maintain a high ratio of ammonia oxidizing bacteria and also tended to keep dead cells. The microfauna in the MSAS process was unstable and changed a lot seasonally, but it wouldn't affect the treatment efficiency. Moreover, the specific activities of nitrification, denitrification and organic removal fluctuated largely and seasonally, and were lower than those in the CAS process. However, their volumetric activities were higher than those in the CAS process because the MSAS process could maintain very high biomass concentration. Dehydrogenase activity, ATP content and oxygen utilization rate were measured to estimate the bacterial activities and viability. The OUR and ATP has different relationship in the both processes. Polysaccharides were also determined as metabolic products.

Performance of fixed film media integrated in activated sludge reactors to enhance nitrogen removal

1994 ◽  
Vol 30 (11) ◽  
pp. 13-24 ◽  
Author(s):  
Dipankar Sen ◽  
Pramod Mitta ◽  
Clifford W. Randall
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Biofilm Growth ◽  
Ammonium N ◽  
Suspended Growth ◽  
Fixed Film ◽  
The Media ◽  
Aerobic Zone ◽  
Sponge Media ◽  
Aerobic Cell

Nitrification and denitrification were evaluated in multiple CSTR continuous flow fixed film systems at 12°C. Three systems were operated with three types of media installations and a fourth as a control without media. The media configurations evaluated included: (i) frame mounted fine pore sponge media supported on wires; (ii) free floating fine pore sponge media; and (iii) fixed location frame mounted rope media (ringlace). The pore size for sponge media was 14 pores per centimeter. Each system included a two-cell anaerobic zone with 17 percent of total volume, two-cell anoxic zone with 17 percent of total volume, and a three-cell aerobic zone with 64 percent of total volume. The multi-cell configuration was used to maximize kinetics of removal with suspended growth biomass and evaluate improvements in nitrogen removal beyond the levels achieved with suspended growth. At the optimum location (aerobic cells 1 and 2), the nitrification in cells containing free-floating sponges was 143 percent of the control at aerobic MCRTs of 3.1 and 3.4 days, with 35 percent media volume to cell volume. The nitrification with rope media was 136 percent of the control in middle third of the aerobic zone. Removals with ringlace were poorer in the first aerobic cell operating at higher COD levels, and in the third aerobic cell which did not contain sufficient biofilm growth at low levels of COD. Nitrification was 14 percent higher in Systems 1 and 2 with fixed and free floating sponges, respectively, and 8 percent higher in System 3 (ringlace) when all systems were spiked with 20 mg/L additional ammonium over a 24 hour period. Optimizing location of the media, with higher density of media at locations where adequate COD and ammonium-N are available for biofilm growth increase nitrification on media. Studies in full scale systems show that COD and ammonium-N concentrations at downstream locations in the activated sludge basin increase during peak flows and with step feed of wastewater. This helps increase biofilm growth and improve nitrification on the media downstream locations. Denitrification observed in the aerobic cells of the fixed film systems was in excess of the control. All aerobic cells were operated at D.O. levels in excess of 6.0 mg/L. The fraction of total denitrification under aerobic conditions was 0.0 in the control as compared to 0.14 to 0.24 with ringlace media and fixed sponge media, respectively, at an aerobic MCRT 3.1 days. Fraction aerobic denitrification in all systems increased with an increase in MCRT of suspended growth - to 0.21 in the control and 0.35 and 0.39 with ringlace and sponges, respectively, at aerobic MCRTs of 3.4 to 7.7 days.

Dynamic modeling of nitrogen removal for a three-stage integrated fixed-film activated sludge process treating municipal wastewater

2017 ◽  
Vol 41 (2) ◽  
pp. 237-247 ◽  
Author(s):  
Paul Moretti ◽  
Jean-Marc Choubert ◽  
Jean-Pierre Canler ◽  
Pierre Buffière ◽  
Olivier Pétrimaux ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Dynamic Modeling ◽  
Nitrogen Removal ◽  
Municipal Wastewater ◽  
Activated Sludge Process ◽  
Fixed Film

Full-scale evaluation of an integrated fixed-film activated sludge (IFAS) process for enhanced nitrogen removal

1996 ◽  
Vol 33 (12) ◽  
pp. 155-162 ◽  
Author(s):  
Clifford W. Randall ◽  
Dipankar Sen
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Plug Flow ◽  
Treatment Plant ◽  
Nitrification Rate ◽  
A Value ◽  
Fixed Film ◽  
Control Section ◽  
The Media ◽  
Retrofit Design

One of the two trains of the 37,000 m3/d Annapolis, Maryland step aeration activated sludge treatment plant was modified for single-sludge anoxic-aerobic operation, and then fixed-film media were integrated into the aerobic zone to enhance nitrification. Rope-like Ringlace media was selected for integration, and 30,000 meters were installed in a volume of 475 m3 for a pilot demonstration. The purpose of the integrated fixed-film media was to upgrade the short hydraulic retention time (HRT) basin (6 hrs nominal) for efficient, year-round nitrogen removal without construction to increase basin volume. An engineering study had concluded that upgrading the facility for year round complete nitrification, without nitrogen removal, would cost US$24 million. The modified train was operated for 12 months, six in the plug-flow MLE configuration, and six in a step-feed configuration. The integrated Ringlace media increased the nitrification rate per unit volume to 225% of that observed in the control section, attaining a value of 1.75 kg/d NH3-N per linear meter at 15°C. The media also increased denitrification in the aerobic media section to the extent that between 30 and 88% of the nitrates formed in the section were denitrified within it, permitting a potential 25% or more reduction in the volume of the anoxic zone. An IFAS retrofit design was developed which incorporated step-feed operation, and reduced the projected construction cost to US$9.2 million.

Sign in / Sign up

Export Citation Format

Share Document