\\l United States Environmental Protection Agency Risk Reduction Engineering Laboratory Cincinnati OH 45268 Research and Development EPA/600/S2-89/003 Feb. 1990 &ER& Project Summary Capital and O&M Cost Estimates for Attached Growth Biological Wastewater Treatment Processes Henry H. Benjes, Jr. Data for projecting process capabilities of attached growth biological wastewater treatment systems and procedures for making design calculations are presented in this report. Carbonaceous oxidation (secondary treatment) and single- stage nitrification design examples are given. Information for estimating average construction costs and operation and maintenance (O&M) requirements are presented for typical wastewater treatment plants ranging in size from 1 to 100 mgd capacity. Estimated average construction costs and O&M requirements for individual unit processes are related graphically to appropriate single parameters for each component. Construction costs are broken down into labor and materials components to enable the costs to be inflated using readily available Bureau of Labor Statistics Wholesale Price Indices. O&M requirements are given for labor, energy, and maintenance materials and supplies so that appropriate current, local unit costs can be used to estimate annual costs. The data in this report provide a means for estimating anticipated average performance and costs for facilities, but they should not be substituted for detailed assessment of local conditions or recognition of changing design requirements. This Project Summary was developed by EPA's Risk Reduction Engineering Laboratory, Cincinnati, OH, to announce key findings of the research project that Is fully documented In a separate report of the same title (see Project Report ordering Information at back). Introduction This report represents recommended design procedures, reviews performance design procedures, reviews performance capabilities, and presents cost estimating guidelines for municipal wastewater treatment plants incorporating attached growth biological processes for secondary treatment. Attached growth treatment processes are based on the development of biological growth on a media surface, either by passing wastewater over stationary media or by moving media through a wastewater bath. Attached growth processes are most commonly exemplified by the trickling filter. The rock media trickling filter has been recognized and used since 1898. There are nearly 4,000 municipal trickling filter wastewater treatment plans in the United States. Objectives The objectives of this report are to develop suggested design procedures for attached growth biological treatment processes, assess the accuracy of those procedures, and present guidelines for ------- estimating capital costs and O&M requirements. Commonly used design procedures for biological treatment processes are empirical in nature, based on experienced results. Available design procedures are reviewed to assess their utility in assisting the engineer in predicting attached growth performance. Once a design has been developed and the proposed facilities sized, estimating capital costs and O&M requirements must be considered. Capital costs include the cost of construction; engineering, legal, and administrative services; land; and interest during construction. This report emphasizes the development of construction costs. Other costs, except land, may be related to construction costs. Land is a variable that cannot be typified. General information for plant construction costs has been available for some time; however, this information is often presented for an overall system, rather than in terms of unit processes. The variability of combinations of several unit processes limits the use of these data. By separating plant costs into categories of unit processes, historical cost data from existing plants may be applied to similar processes in project planning. Attached Growth Processes Considered Four attached growth processes are examined in the report, including rock media trickling filters, plastic media trickling filters, rotating biological contactors, and trickling filter/solids contact, which is an attached growth process enhanced by a coupled- suspended growth process. The six process alternatives analyzed in the study are listed in Table 1. These processes are generally incorporated into liquid stream system designs that include pretreatment via screening and grit removal, primary and final sedimentation, sludge pumping, recirculation pumping, and effluent disinfection. Sludge handling selection varies depending on local economic considerations. • Rock media trickling filters are a simple, single-stage treatment process. Rock media varies in diameter from 1 to 4 in. and are designed with depths of 3 to 10 ft. Wastewater is continuously sprayed over the stationary media, which supports biological growth. Treated wastewater is collected in a underdrain system where it is recycled and/or directed to the final settler. Biological growth sloughs from the media resulting in the need for final sedimentation. Rock media filters are usually employed for secondary treatment (carbonaceous removal) only. • Plastic media trickling filters were introduced to overcome the limitations of rock media. Plastic media trickling filters may be designed much deeper (commonly 21 ft deep) than rock filters since the media is very light. Corrugated sheet modules are delivered in bundles that are then cut to size and placed in the media towers. Plastic rings, on the other hand, are dumped, making installation simple. Recirculation is typically taken directly from the trickling filter underflow, although some designs recycle the final sedimentation tank underflow. Plastic media have been used for both carbonaceous removal and nitrification. • Rotating biological contactors (RBC's) were developed in Europe and introduced in the United States in the 1970's. The media, which supports biological growth, is generally 12 ft in diameter and rotated through a bath of wastewater. The media is alternately exposed to the liquid and to the atmosphere. RBC effluent is typically not recirculated. Originally, the media was designed as a series of closely- spaced, parallel, flat discs with a specific surface area of 20 to 25 ft2/ft3. The newer lattice-structured media Table f. Biological Treatment Process Alternatives Treatment Process offers about 50% more specific si area than the disc-type constru The lattice-structured media, and lesser extent the disc structure fragile and should be protected direct exposure to sun, wind, weather. Therefore, the medii enclosed in either superstructu individual shaft covers. Media re can be provided by either mecri drives or air motivation. RBC's m used for either secondary treatm secondary treatment plus nitrifi applications. Trickling fitter/solids contact (TFI a development that enhance reliability of the trickling filt incorporating suspended g treatment in the process. There been other "coupled" atti growth/suspended growth pro< that have been used in an atte offset the disadvantages assc with the two processes. Wil processes there can be variations in relative organic I rates, locations and quantit recycle, and process arrangem a consequence, there were an i process alternatives under the category of "coupled tri filter/suspended growth" proce; TF/SC variation represents processes in this report. The TF/SC process uses the filter (TF) as the primary me remove organics and a ven hydraulic retention time aeratic (SC) to polish that tricklin effluent. Where the treat me effluent quality needs only t secondary treatment stand; conventional final sedimentatic is used. Where higher quality standards are required, sedimentation basin with a flo< center well is used. The TF/SC is not used for nitrification. nitrification is required, the segment must be larger ; process is no longer categori; TF/SC process. Carbonaceous Removal Only Single-Stage Carb. Rem Nitrification Rock Media Trickling Filter Plastic Media Trickling Filter RBC's TricUing Filter/Solids Contact ------- ocedure i three-step approach was used to nduct the work of this study. The first p was to develop design criteria for atment plant liquid and solids handling it processes applicable to attached iwth treatment systems. To thoroughly aluate a complete treatment system ernative, it is necessary to consider the sign and costs of ancillary treatment its, such as solids handling processes d functional parts of the total project. tailed construction costs and O&M }uirements for typical additional unit ocesses and functional units that mplete the system alternatives are :luded. The second step was to collect, alyze, and formulate the construction st and O&M requirements for each unit ocess. Comparative cost information is esented for certain design odifications, e.g., alternative solids ocessing equipment. The third step was to develop flow agrams for each of the systems. pical flow schemes meeting the state rformance requirements have been eluded. The attached growth processes timated have been sized to correspond design flows ranging from 1 to 100 gd. Within this range, six nominal plant pacities have been evaluated: 1, 5, 10, , 50, and 100 mgd. The following unit process costs have en included in the complete final sport: law wastewater pumping '.hlorine feed & storage facilities Derated grit removal & flow measurement >O2 storage & feed equipment 'rimary treatment screens lotation sludge thickeners edimentation basins ludge handling tanks Sludge pumping stations Anaerobic digesters Trickling filters Filter presses Rotating biological contactors Centrifuges Inplant & recycle pumping stations Multiple hearth incinerators Aeration basins Sludge & ash lagoons Mechanical aeration equipment Land spreading of sludge Blowers Sand drying beds Diffused air aeration equipment Sludge composting Effluent filtration Pipeline transport Chlorine contact basins Truck transport The costs have been presented in two forms. The construction cost components have been itemized for several sizes of the unit process so they can be updated according to the inflation rates for the individual components. The total updated costs (September 1987) are also presented graphically so they can be used for any size treatment system. Total annual costs (September 1987) for the different size plants and treatment options are summarized. These costs, presented in terms of $/1,000 gal wastewater treated, are the sum of a plant's annual O&M costs and its capital costs amortized for 20 yr at 10% divided by the total quantity of wastewater treatment annually. The most cost-effective treatment method is indicated in Table 2. RBC's are estimated to be the most economical attached growth process for carbonaceous oxidation and for single- stage nitrification. The estimated costs for the TF/SC process are essentially the same as for the RBC process above 10 mgd. The relative ranking of these costs for estimating purposes should be tempered by site-specific conditions and by engineering judgment. The use of these cost estimating procedures results in project estimates that are very close to the experienced costs to as much as 30% different than experienced costs. The relative accuracy, comparing competing alternatives should be within 10%. Design Approaches Performance data from operating systems are used to evaluate the various methods for designing attached growth processes. This is particularly important since design must be based on achieving specific effluent quality. The design approaches for removal in rock and plastic media trickling filters and RBC's are evaluated first, followed by performance evaluation and the design approach for the TF/SC process Attached growth processes are characterized by a decreasing concentration of organics passing over a film of attached bacterial growth. Organic and oxygen fluxes from the carriage water to the growth are proportional to their concentrations. The surface area is the major parameter in attached growth process evaluation if the organic loading rate is not so high that either the rate of organic assimilation by bacteria or the rate of oxygen transfer would limit the removal rate. Greater surface area per unit volume will support more bacterial growth and provide more contact opportunities between organics and bacteria. However, there are many complicating factors that obviate the effect of media surface area. These factors have relegated attached growth process design to empirical relationships that are of limited usefulness. ttile 2. Summary of Total Annual Costs for Plants Utilizing Attached Growth Treatment Processes Annual Cost Summary, $11000 gal Plant Size, mgd Process 10 25 'ingle-Stage Nitrification lastic Media IBC's 3.28 2.65 2.07 1.62 1.80 1.40 1.44 1.12 50 100 Carbonaceous Oxidation toc/t Media lastic Media IBC's f/SC 3.86 2.93 2.53 3.09 2.59 1.74 1.48 1.69 2.32 1.41 1.22 1.38 1.88 1.20 0.99 1.02 1.67 0.97 0.82 0.85 1.60 0.94 0.77 0.79 1.18 0.94 1.17 0.94 ------- Empirical models based on statistical curve fitting of data to variations in operating conditions and physical facilities are most commonly used by design engineers. The actual phenomenon involved in organics removal may or may not be understood from the resulting statistical model. These empirical models yield varying results that do not reflect the true removal phenomenon. It is important to realize this limitation and restrict the application of the empirical models to the range of operating conditions and wastewater characteristics for which they have been developed. Techniques classified as rational approaches better describe the removal mechanisms, but they also present difficulty in application. The Williamson and McCarty biofilm model represents the rational approach, although it is rather complex and may be beyond general use by design engineers. This model considers many factors that describe substrate utilization by biofilms. Basically, it predicts soluble substrate removal based on limitations of oxygen and substrate diffusion through the liquid and the biofilm into the bacteria. It also considers the simultaneous effects of biochemical reactions. The biofilm surface area is a key design parameter. Empirical Models Empirical predictive design techniques for trickling filters have been presented by several investigators. The complete project report for this study describes several empirical models including the National Research Council (NRC), Caller and Gotaas, modified Velz, and the rational model of Williamson and McCarty. A variation of the basic Velz equation is presented in this summary report: , BOD_ out, In 5__ =K L BOD, in J 69SQ/A — 6960j (1) where: K = coefficient related to media volume gpm"/(ft3)" Q =flow rate to the filter including recirculation, mgd A = filter surface area, ft2 D = filter depth, ft n = hydraulic coefficient v = filter volume. 1,000 ft3 The variation in K with varying media wetting rates (applied hydraulic loading to plan surface area of trickling filter) is predicted by the following equation for rock media trickling filters: K = 0.25 + (1nqw)/20 (2) where: qw = media wetting rate, gpm/ft2 Model Evaluation The designer is faced with selecting a media volume for which the effluent criteria may be attained with a reasonable degree of confidence. In the following discussion, data are presented for existing attached growth systems. The Velz model generally is used to predict effluent soluble BOD5 from the trickling filter. Sometimes it is used with influent soluble BOD5. Since influent BOD5 is hydrolyzed quickly, the author believes it is inappropriate to use influent soluble BOD5. The model has been applied in this report to predict effluent total BOD5 after the final clarifier. The model might be more precise if used to predict effluent soluble BOD5 and if effluent insoluble BOD5 were estimated, but the precision of the model is not adequate to justify such refinements. Tables 3, 4, and 5 present field data and predicted results for rock media, fabricated media, and RBC systems, respectively. Variables used in the equations to predict performance are given in Table 6. It is noteworthy that the K values in Equation 1 for rock media trickling filters approach those of plastic media at higher wetting rates: Wetting Rate (qj, gpm/ft2 K, 0.1 0.2 0.3 0.4 0.15 0.18 0.20 0.22 An "n" value of 0.5 has been used in these comparisons. The performance of plastic media trickling filters was predicted using a K of 0.21 gpmos/ft15 for wetting rates varying from 0.5 to 2.27 gpm/ft2 The probable reason that the specific surface area of plastic media is not more effectively utilized at conventional organic loading rates in comparison to rock media is oxygen diffusion limitations. The treatment efficiency achieved with both typ media will be determined b< availability of oxygen and effectiveness of the media to aera wastewater. Richards and Reinhardt invest different configurations of plastic using variable depths with the media volume and found performance improved with depth media specific surface areas used i investigation did not vary. Their fi indicated that the 45° and 60° cro.1 configurations performed better either the vertical configuration or r.' dump media. When they evaluatec plant data, they found an "n" of ( best mimic performance of soluble removal. They used an "n" of compare field data. Rotating Media Biological Contractor (RBC's) The design approaches propos RBC manufacturers are primarily on "rational" models. One such ap is summarized in the grai relationship between effective surface area (expressed as flow f of surface area) and effluent : BOD5 shown in Figure 1. relationship indicates benefits fron media with high specific surface The design approach shown in F is based on soluble BOD5 in the and effluent. Unfortunately, the soluble BOD5 portion is highly v For example, the following havi reported for soluble BO05 in | effluents: Plant Soluble BO Pewaukee, Wl Seattle, WA Tucson, AR 66 31-50(41 av 50-71 (56 av The use of influent soluble assumes that insoluble BOD5 is r by some mechanism other than b stabilization. Some insoluble c may be incorporated in biologi and removed by sedimentation, t will be hydrolyzed and metal Therefore, a design approach based on only soluble organic lo a liberal one. Since hydr partjculate organics as well as organics are available substr; design (substrate removal ap empirical approach, or other) st based on total influent substrate. ------- To provide a design approach more insistent with stationary media attached •owth processes and to enable realistic valuation of the available data, Equation has been applied to the RBC process. vailable data for mechanically driven sc and lattice-type RBC systems have een evaluated using this approach and ere summarized earlier in Table 4. lese data represent both full-scale and lot-plant installations. Because lattice media have greater jrface area per unit volume than disc ledia, an analysis of the data was also erformed relating BOD5 removal to »edia surface area according to the illowing equation: BOD out In - - - I = -K (3) BOD. in 5 The performance data in Table 4 have een evaluated in terms of ks, the (efficient related to media surface area, pmn/(ft2)". Figure 2 represents a robability distribution plot of the alculated ks values that imply that media pecific surface area is a more significant arameter for the design of RBC process erformance than media volume. Using a s value of 0.062 gpm°5/ft and media densities of 20 ft2/ft3 for the disc media and 30 ft2/ft,3 for the lattice media, the standard error of estimate would be 5 mg/L. Trickling Filter/Solids Contact The inability to accurately predict trickling filter process performance and the need for uniformly reliable effluent quality have led to the development of a variety of combined trickling filter- suspended growth systems. The TF/SC process is one of the coupled processes consisting of a trickling filter followed by an aeration basin. The trickling filter is lightly loaded, usually 20 to 50 Ib BOD5/1,000 ft3/day. The aeration basin detention time may be 10 min to as long as 1 hr. The TF/SC process relies on the trickling filter to stabilize the majority of the organics while the aeration basin completes the stabilization of the organics and conglomerates the solids into a settleable floe. The evaluation of coupled processes is complicated by the difficulty in separating the removal occurring in the individual process units. The data presented by most investigators are not complete; therefore, a thorough evaluation is not possible. The design and evaluation procedures used in this report are based on the following: • Assume the trickling filter performs in the same manner that it would when operating alone. • The trickling filer soluble BOD will exert a synthesis oxygen demand of 0.5 Ib 02/lb soluble BOD5 synthesized. • The endogenous oxygen demand will be 1.2 Ib 02/lb insoluble BOD5 or synthesized cellular material. An example of the application of these concepts is presented in Table 7 for the field data collected for the Corvallis, OR, TF/SC plant. The Corvallis plant consists of a trickling filter followed by a solids contact aeration basin of 0.02 mil gal volume. The final report describes temperature consideration, nitrification design equations, and example design illustrations. Conclusions This report is a consolidated volume describing the methodology involved in designing attached growth biological wastewater treatment processes to achieve carbonaceous oxidation able 3. Comparison of Predicated vs. Measured Effluent BOD5 Using Rock Media Trickling Filter Data Plant Location Aurora, IL Dayton, OH Oruham, NC Madison, Wl Richard, TX "lainfield, NJ Great Neck, NY Oklahoma City, OK -reemont, OH Storm Lake, IA lichland, WA Misal, CA Chapel Hill, NC Dallas, TX Bridgeport, Ml Jass City, Ml Charlotte, Ml lillsdale, Ml apeer, Ml •tate Prison, Ml assar, Ml nglewood, CO orvallis, OR orvallis, OR Depth, ft 6.0 7.5 7.0 10.0 6.5 6.0 4.0 6.0 3.3 8.0 4.5 32 4.25 7.5 6.0 6.0 6.0 6.0 5.8 8.0 5.6 4.4 8.0 8.0 R — — — — - 06 1.0 1.0 1.5 2.1 2.8 3.1 2.0 0.5 1.2 1.3 — — 0.3 0.1 1.7 1.0 2.4 05 0/A, mgd/ac 2.1 3.5 1.9 2.4 3.9 2.4 7.8 16.3 19.0 21.5 19.6 20.8 16.3 5.6 20.6 10.0 7.7 3.6 73.5 3.8 9.2 74.8 24.6 24.6 W/V, Ib 8005/7,000 fWday 4.4 12 13 6.4 73.3 25 20 78 41 62 44 53 19 21.4 29 23 29 10 22 13 6 60 16 19 BODj, In 70 138 261 738 778 76 117 300 95 381 118 185 77 225 99 151 119 91 65 153 59 158 86 49 mg/L Out 14 33 68 33 20 73 20 66 27 67 20 24 44 37 42 33 63 32 23 17 29 46 32 31 Predicted Effluent BODj, mg/L, from Equation 1 20 34 66 27 32 15 32 78 32 63 25 49 79 45 26 30 39 26 27 34 77 49 32 18 ------- Table 4. Comparison of Predicted vs. Measured Effluent BOD5 Using Plastic Media Trickling Filter Data Plant Location Indianapolis, IN Stockton, CA Akron, OH Buena Vista, Ml Bay City, Ml Essexville, Ml Greenville, Ml Rockwood, Ml ' Indio, CA 2 Linden Rochelle, NJ 3 3 Media Plastic Plastic Plastic dumped Plastic Plastic Plastic Plastic Plastic Plastic Plastic Plastic Plastic Depth, ft 21.5 21.5 25.5 20.0 21.5 21.5 21.5 22.0 33.0 21.5 20.0 10.0 q, gpm/ft2 2.0 0.28 0.36 0.46 0.90 0.75 0.46 0.32 0.27 1.10 1.4 0.6 Rate, gpm/ft2 2.0 0.71 0.75 1.20 1.1 1.50 0.50 0.97 -- 2.77 1.4 0.06 ' Drury, D. D., Carmota, III, J., and Degadillo, A., "Evaluation of High Density Cross Flow Media for 58(5):364, May 1986. 2Fillos, J., Nierstedt, R., and Donahur, A, "Full Scale Evaluation of Plastic Media Roughing Filters, New Orleans, LA, October 1984. 3 Richards, T. and Reinhart, D., "Evaluation of Plastic Media in Trickling Filters," JWPCF, 58(7):774 8C In 112 240 120 54 79 23 62 61 62 100 78 76 JDs, mg/L Out 57 40 20 21 18 11 15 23 72 50 29 41 Predict Effluent B mrj/L fn Equatio, 56 38 18 14 28 7 15 10 46 40 36 42 Rehabilitating an Existing Trickling Filter, " J " Presented at 57th Annual WPCF Con fere , July 1986 Table 5. Comparison of Predicted vs. Measured Effluent BOD5 Attached Growth Model Using RBC Data* Plant Location Pewaukee, Wl Pewaukee, Wl Edgewater, NJ Gladstone, Ml Gladstone, Ml Woodland, WA Kirksville, MO Georgetown, KY Brainerd, MN Media Disc Disc Lattice Disc Lattice Lattice Lattice Lattice Lattice Volume, ft3 197 10,450 6,110 196 16,300 2,413 63,100 25,240 40.715 0, gpm 8.3 235.0 333.0 10.4 550.0 104.0 904.0 765.0 950.0 SOOg, In 172 119 133 100 106 175 164 150 80 mg/L Out 33 20 38 32 20 28 15 21 17 Predict Effluent £ mg/L fr Equatio 38 15 35 26 20 40 12 25 20 'Lehman, P. J., 'Start-up and Operating Characteristics of an RBC Facility in a Cold Climate," JWPCF, 55(10):1233, October 1983. Table 6. Variables Used for Models Evaluation Modified Velz Parameters Rock Media Plastic Media RBC's n K (Equation 1) 0.5 (Equation 2) 0.5 0.21 0.5 0.308 (secondary treatment) and nitrification of domestic wastewater. The theoretical considerations given to design are reviewed, and detailed examples using the most accurate approaches are presented. Cost analyses were facilitated by using a computer; however, the procedures are straightforward and can easily be done manually. Several mathematical models have been used to design attached growth systems. None are particularly accurate in predicting process performai some are quite complicatt carbonaceous removal, the Velz is as accurate as any and conveniently applied to all growth processes. The Velz equ ------- 30 25 20 Q O 00 J> 15 to 0) 70- 5 - /?flC Process Design Criteria Domestic Wastewater Treatment Wastewater Temperature = 5 4-Stage Operation Influent Soluhif «OOS mg/L ISO 120 100 1 1 1 1 1 1— 0 0.5 1.0 1.5 2.0 2.5 3.0 Hydraulic Loading, gpd. ft2 Igun 1. Manufacturer's design approach for RBC's. 3.5 —i— 4.0 —i— 4.S a applied to rock media, plastic or spropriate modifications. Total plant capital and O&M costs have »en estimated for various size facilities sing attached growth biological •ocesses for secondary treatment arbonaceous oxidation) and for nitrification in the final report. RBC's are estimated to be the most economical attached growth process for carbonaceous oxidation and for single- stage nitrification. The estimated costs for the TF/SC process are essentially the same as for the RCB process above 10 mgd. The relative ranking of these costs for estimating purposes should be tempered by site-specific conditions and engineering judgment. This report was submitted in fulfillment of Contract No. 68-03-2556 by CWC/HDR Engineers under the sponsorship of the U.S. Environmental Protection Agency. ------- 0.088 0.080 0.072 0.064 0.056 0.048 0.040 5 10 20 30 40 50 60 70 80 90 Percent of Time Ka is Equal to or Less Than Stated Value Figure 2. Probability of RBC performance based on media surface area ------- 'able 7. Evaluation of TF/SC Process lorvallis TF/SC Plant (1983-1984) Month Q, mgd Temp., °C Influent 800$, mg/L TSS, mg/L TF Effluent SODj, mg/L SSOOg, mg/L rSS, mg/L Cn mg/L Cg, mg/L Or, mgd1 Solids Aeration, Ib2 Reaeration, Ib3 Clarifier, Ib4 Total, Ib SRT, days BODs/TSS Ratio6 Oxygen Demand, Ib/day Synthesis7 Endogenous Aeration^ Endogenous Reaeration9 Oxygen Demand, mg/Uhr O2 Demand Aeration10 O2 Demand Reaeration" Apr. 12.2 15 66 75 25 6 63 13,075 3,110 3.8 520 2,180 17,300 20,000 3.1 0.3 90 63 266 38 67 May 74 18 90 82 34 5 72 8,091 2,150 2.7 360 1,350 7,600 9,310 2.1 0.4 71 72 270 36 68 June 7.3 20 87 74 32 6 61 8,180 1,940 2.3 324 1,364 6,450 8,138 2.2 0.4 91 75 154 42 39 July 6.2 20 78 68 28 5 60 6,345 1,768 2.4 295 1,060 5,280 6.635 1.9 0.4 69 68 244 34 61 Aug. 6.2 22 72 63 29 5 57 5,437 1,557 2.5 260 907 4,700 5,867 1.8 0.4 74 69 240 36 60 Sept. 5.7 22 94 68 39 8 59 5,415 1.675 2.6 280 903 4,800 5,983 1.9 0.53 112 98 170 53 43 Oct, 5.6 21 114 66 38 8 56 70,293 2,948 2.2 490 1,720 8,040 10,250 3.3 0.54 108 164 572 68 143 Nov. 15.2 17 56 56 33 6 55 13,703 3,571 5.4 595 2,285 25,560 28,340 4.0 0.5 106 139 534 61 134 Dec. 17.9 14 35 58 26 4 59 76,739 4,278 6.3 703 2,690 35,520 38,973 4.5 0.36 63 707 368 43 92 Jan. 13.4 14 49 56 26 4 54 17,170 4,777 5.2 797 2,870 30,800 34,464 5.5 0.42 58 127 457 46 774 Feb. 16.6 13 56 64 22 3 59 76,523 4,832 6.9 806 2,760 39,390 42,956 4.8 0.32 44 91 312 34 78 Mar. 12.7 13 48 64 22 3 58 75,353 4,982 6.1 830 2,560 32,550 35,940 5.3 0.33 41 97 299 35 75 ' Q, = < 2 Aeration Ib solids = CaxVax 8.34 = Cax 0.02 x 8.34 3 Reaeration Ib solids = CrVrx8.34 = Crx 0.02 x 5.34 4 Clarifier Ib solids = (0, * Q,) Ca x 8.34/24, assuming 1-hr time to achieve Cr 5 Total Ib solids/(Q in x TF TSS out x 8.34) « BODs/TSS ratio = (TF 8O05 out - TF SBOD5 out)/TF TSS out 7 Synthesis Oxygen, 0.5 xTF SBOD5 out x 24 x Vax 8.34 KSK, KSK, ta+1 » Endogenous Oxygen, Aeration, Ibid = 1.2 Cax 8.34 x (BODs/TSS ratio) ' Endogenous Oxygen, Reaeration, Ib/d = 1.2 Crx 8.34 x (BODJTSS ra '° Oxygen Demand Aeration, mg/Uhr = (Synthesis + Endogenous Aeration)/(V, x 8.34 x 24) '' Oxygen Demand Reaeration, mg/Uhr = (Endogenous Aeratin)/(Vr x 8.34 x 24) Vhere: Q, = RAS flow mgd 0, = In flow mgd Ca = MLSS, mg/L Cr = RAS concentration, mg/L V, = Aeration basin volume, mil gal Vr = Reaeration basin volume, mil gal TF SS out - trickling filter effluent suspended solids, mg/L TT BOD out = trickling filter effluent 800$, mg/L TF SBOD out = trickling filter effluent soluble 800$, mg/L Ks= lShri@20'C Ke = 0.02 hr> @ 20"C Kt = 1.072 (T-20) t = aeration detention time, hr ------- Henry H. Benjes, Jr., is with CWC/HDR Engineers, Dallas, TX 75230. John J. Convery is the EPA Project Officer (see below). The complete report, entitled "Capital and O&M Cost Estimates for Attached Growth Biological Wastewater Treatment Processes," (Order No. PB 89-148 3241 AS; Cost: $36.95, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Risk Reduction Engineering Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 10 ------- 11 Is « C in o HOOWO OHO O 00 2 o f. 3 I HI H H» H O CM4 O ON s W «B O x r'l' O ------- |