Data processing: measuring – calibrating – or testing – Measurement system in a specific environment – Chemical analysis
Reexamination Certificate
2002-02-19
2004-02-24
Barlow, John (Department: 2863)
Data processing: measuring, calibrating, or testing
Measurement system in a specific environment
Chemical analysis
C435S286500
Reexamination Certificate
active
06697740
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method and system for controlling and sampling of batch processes employed for the treatment of water and wastewater. More specifically, the method and apparatus of the invention provides a means of synchronizing sampling of batch water and/or batch wastewater treatment processes for adjustment and control of the batch treatment processes.
2. Description of Background Art
Over the past 10 years there has been a revival of use of the sequencing batch reactor (SBR) used for suspended growth activated sludge processes because of the inherently more efficient batch settling and often higher treatment efficiency for batch organic contaminants removal than is possible with the conventional continuous flow activated sludge process. The process employed in a SBR is often is referred to as the SBR process which uses the same vessel for batch biological reactions and quiescent batch settling. Thus, the SBR process eliminates the major cost of dedicated final clarifiers necessary for the conventional activated sludge process as well as improving solids removal performance.
However the SBR process has several disadvantages, the principal one being that it does not operate with a constant level and continuous flow, but requires intermittent operation for cycles of fill, react, settle, decant, waste and idle. Typical sequence level fluctuations are 30% to 50% of the maximum operating depth or as much as 5 to 10 feet of level fluctuations. The result is a much lower use to total volume ratio than the conventional activated sludge process. Accordingly, the SBR process is generally not cost effective for flows greater than five to ten million gallons per day (MGD).
Another disadvantage of the SBR process is that significant head loss occurs from the influent to the final effluent, requiring additional energy and pumping costs. Additionally, because the effluent flow is not continuous, flow equalization systems may be required to prevent peak loadings and adverse impacts on waters receiving the effluent from the SBR process as well as downstream processes.
Still another disadvantage of the SBR process is the requirement for labor-intensive operation under conditions of varying hydraulic and organic loadings. Since the SBR process reactors operate based on levels and timers any variation in loading requiring adjustments cannot be determined unless operating personnel are in attendance for the complete batch treatment sequence and manually sample or trigger a sampler in synchronization with the prevailing level and timer settings.
Finally, the basic process and design limitations of the SBR process make it difficult to achieve the same high efficiency biological nutrient removal possible using the continuous flow activated sludge process, especially in a small system and those subjected to wide variations in either hydraulic or organic loadings, or both.
Several improvements have been attempted to overcome the limitations of the conventional SBR process. A continuous inflow, partitioned SBR process is disclosed in U.S. Pat. No. 4,468,327, and cyclically operated intermittent flow path sequential cycle, multi-zoned recycle SBR process disclosed in U.S. Pat. Nos. 4,663,044 and 5,013,441. Significant level fluctuations, head losses and intermittent high flow rate discharges, however, still prevent these processes from overcoming all the limitations of the conventional SBR process.
Attempts have also been made over the years to overcome the level variation limitations of all SBR type processes and the cost of dedicated final clarifiers for the conventional activated sludge process. U.S. Pat. No. 3,470,092 illustrates a first attempt to develop a new suspended growth activated sludge process utilizing the concepts of both batch treatment and continuous flow. This two cell process was partially interconnected at the water surface. The alternate cell feed concept was not effective because it did not achieve a high treatment efficiency, had a low aerator utilization factor, and required long detention times to operate, resulting in expensive systems. U.S. Pat. No. 4,179,366 discloses addition of a third bottom interconnected cell, but also suffered from low treatment efficiency and ineffective changeover of untreated wastewater from the first cell to the third cell. The processes disclosed by both patents also required significant level fluctuations in the treatment cells between operating cycles which made it difficult to control flows and operate fixed, level-sensitive mechanical aeration systems.
German Patent No. 3,147,920 discloses the same three cell concept as U.S. Pat. No. 4,179,366. Although this three cell process achieved a more constant level, and overcame some of the limitations of the prior art, the process failed because it relied on expensive and unreliable mechanical gates to separate the treatment cells at various cycle times, and because treatment efficiency and effectiveness was too low to be commercially useful.
French Patent No. 2550522 describes another constant level apparatus including three separate, identical basins. This process required a large, expensive treatment system because three independent basins were required, only ⅓ of the total treatment volume was used for biological treatment at any time, and only ⅓ of the aeration equipment could be used at one time.
In spite of these attempts to improve on the performance and effectiveness of the SBR and conventional activated sludge processes, they do not provide higher treatment efficiency and hence they are not significantly more cost effective. Such attempts have either failed to totally achieve the desired benefits, or have new inherent disadvantages, which result in little or no net benefits compared to conventional methods.
Prior attempts to develop constant level processes to improve on the conventional suspended growth activated sludge process rely on the management control and recycle of mixed liquor suspended solids by back flushing or forward flushing through or around the treatment system by control of the timing and direction of wastewater flow into and through the treatment system. These methods of solids management differ significantly from variable level SBR's, and also differ from the constant level conventional activated sludge process, which settles the mixed liquor suspended solids in a dedicated final clarifier to collect and recycle the resulting activated sludge back to the aeration basin.
Sewage treatment systems are typically batch operations, flow-through (continuous) operations or a combination thereof. Various schemes, such as back-mixing and the like, are practiced. For relatively small operations which are capital-constrained, batch treatment is usually employed. Typical waste batches contain ammonia, which can be treated, such as with certain aerobic autotropic organisms, to oxidize ammonia to nitrite and then further treat the batch to oxidize the nitrite to nitrate. This is the well-known nitrification process in sewage treatment. To complete elimination of ammonia, the nitrites and nitrates are reduced to nitrogen gas, e.g. denitrification. An aspect of batch sewage treatment, is measurement during treatment of the oxygen consuming potential. Several methods of measurement are used including measuring BOD (e.g. “Biological/Biochemical Oxygen Demand”). Accordingly, batch sewage treatment completion and process timing can be measured as a function of the concentration of ammonia (NH
3
), nitrates
itrites (NO
X
), and BOD. Effective use of the measurement of these parameters is important to the economic viability of efficient batch sewage treatment operations. Such measurements are initiated by sampling of the waste being treated.
Biological nitrogen removal is a two-step process consisting of nitrification and denitrification. Nitrification occurs in the presence of oxygen by microorganisms, which oxidize ammonia to nitrate. Nitrification can occur in (1) suspended growth processes such as acti
Barlow John
Ratner & Prestia
Sun Xiuqin
LandOfFree
Method and system for real-time control of sampling... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for real-time control of sampling..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for real-time control of sampling... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3300062