John Fillos

Impact of inocula and growth mode on the molecular microbial ecology of anaerobic ammonia oxidation (anammox) bioreactor communities.

The composition of distinctly inoculated granular anammox and biofilm-based completely autotrophic nitrogen removal over nitrite (CANON) bioreactors was investigated from start-up through continuous long-term operation via denaturing gradient gel electrophoresis (DGGE) and sequencing. The granular anammox reactor was seeded with sludge from an operational anammox reactor in Strass, Austria. The CANON reactor was seeded with activated sludge from a local wastewater treatment plant in New York City. The principal anammox bacteria (AMX) shifted from members related to Kuenenia stuttgartiensis present in the initial inoculum to members related to Candidatus Brocadia fulgida during pre-enrichment (before this study) and to members related to Candidatus Brocadia sp. 40 (during this study) in the granular reactor. AMX related to C. Brocadia sp. 40 were also enriched from activated sludge in the CANON reactor. The estimated doubling times of AMX in the granular and CANON reactors were 5.3 and 8.9 days, respectively, which are lower than the value of 11 days, reported previously. Both the granular anammox and CANON reactors also fostered significant amounts of ammonia-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB). The fractions of AMX and two groups of NOB were generally similar in the granular anammox and CANON reactors. However, the diversity and fractions of AOB in the two reactors was markedly different. Therefore, it is suggested that the composition of the feed and extant substrate concentrations in the reactor likely select for the microbial community composition more than the inocula and reactor configuration. Further, such selection is not equivalent for all resident communities.

Incorporation of rapid thermal conditioning into a wastewater treatment plant

Abstract Rapid thermal conditioning is a developing technology recently applied to sludge treatment. Sludge is heated rapidly to reaction temperature (up to about 220°C) and quenched after 10 to 30 s. This process reduces the amount of biosolids requiring land disposal by increasing its biodegradability and dewaterability. Rapid thermal conditioning may be incorporated into a wastewater treatment plant where, combined with anaerobic digestion, it would reduce the quantity of biosolids requiring disposal, eliminate the need for polymer coagulant, improve dewaterability, increase methane production, and further reduce the concentration of pathogens. Also, the odor problem associated with traditional thermal conditioning processes is largely minimized. Pilot scale equipment was used to assess the process and provide design parameters for scale-up. Introduction of the process into an existing municipal wastewater treatment plant was then evaluated using the Wards Island Water Pollution Control Plant of New York City as an example. Two alternative flow sheets are shown together with preliminary engineering designs. Cost estimates for these alternatives show a substantial advantage in comparison to present plant operation.

Ozonation of leachates from aged domestic landfills

Abstract Ozonation was evaluated as a treatment process for domestic landfill leachates. Bench-scale batch and continuous flow experiments depicted that the process is effective in color removal but considerably less effective in TOC and ammonia removal. The high buffer capacity of the leachate maintained relatively constant pH through the process. Biodegradability of the leachate as measured by BOD/COD also improved.

Quantitative analysis of methanol in wastewater by GC-MS with direct injection or headspace SPME sample introduction

Monitoring methanol (MeOH) concentration in wastewater treatment processes is important because methanol is a widely used carbon source for denitrification. Headspace solid-phase microextraction (HS-SPME) and direct liquid injection coupled with gas chromatography and mass spectrometry (GC/MS) were studied to analyze methanol in municipal wastewater samples in the μg mL−1 range. The conditions applied for both methods are presented. The extraction parameters for the HS-SPME method, such as SPME fiber selection, extraction temperature and time, agitation, pH value of the solution, and salt effect, were investigated. For the liquid injection method, the critical parameter was to select a polar column, the DB-WAX capillary column. Linear calibration curves were obtained over 3 orders of magnitude using methanol-d3 (MeOH-d3) or acetonitrile (ACN) as an internal standard. Both methods were validated with repeatability and recovery experiments. The liquid injection method requires a smaller injection volume and allows for faster analysis and better precision. The HS-SPME method also has reliable performance with less than 10% error. In addition, the comparison of the two methods on practical applications and maintenance is included.

Implementation of CFD modeling in the performance assessment and optimization of secondary clarifiers: the PVSC case study

The water industry and especially the wastewater treatment sector has come under steadily increasing pressure to optimize their existing and new facilities to meet their discharge limits and reduce overall cost. Gravity separation of solids, producing clarified overflow and thickened solids underflow has long been one of the principal separation processes used in treating secondary effluent. Final settling tanks (FSTs) are a central link in the treatment process and often times act as the limiting step to the maximum solids handling capacity when high throughput requirements need to be met. The Passaic Valley Sewerage Commission (PVSC) is interested in using a computational fluid dynamics (CFD) modeling approach to explore any further FST retrofit alternatives to sustain significantly higher plant influent flows, especially under wet weather conditions. In detail there is an interest in modifying and/or upgrading/optimizing the existing FSTs to handle flows in the range of 280-720 million gallons per day (MGD) (12.25-31.55 m(3)/s) in compliance with the plants effluent discharge limits for total suspended solids (TSS). The CFD model development for this specific plant will be discussed, 2D and 3D simulation results will be presented and initial results of a sensitivity study between two FST effluent weir structure designs will be reviewed at a flow of 550 MGD (∼24 m(3)/s) and 1,800 mg/L MLSS (mixed liquor suspended solids). The latter will provide useful information in determining whether the existing retrofit of one of the FSTs would enable compliance under wet weather conditions and warrants further consideration for implementing it in the remaining FSTs.

Experimental evaluation of the nitrite sensitivity coefficient in granular anammox biomass.

Nitrite is widely reported to inhibit anammox activity and growth. One modeling approach for nitrite impairment of anammox growth is the use of a nitrite sensitivity coefficient which increases the endogenous decay coefficient of anammox bacteria proportionally to nitrite concentration. The objective of this study was to measure nitrite concentration profiles within active anammox granules incubated at fixed bulk nitrite concentrations and to compare these with nitrite concentration profiles predicted by a biofilm model that incorporates the nitrite sensitivity coefficient. We developed an apparatus for the repeated measurement of nitrite concentration profiles along the radius of granular anammox biomass over a period of 6 days at fixed bulk nitrite concentrations. Granular anammox biomass was obtained from a two-stage bench-scale partial nitritation/anammox reactor system. There was no apparent effect of nitrite concentration on nitrite utilization kinetics after 6 days at exposures up to 90 mg NO(2)(-)-N/L. These findings suggest that anammox bacteria tolerate extended exposures to elevated nitrite concentrations, and in its present form, the nitrite sensitivity coefficient is not applicable for anammox growth modeling.