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Beneficial Use of Biosolids

Beneficial Use of Biosolids

7.93

24.Dowdy, R. H., and W. E. Larson (1975), “Metal Uptake by Barley Seedlings Grown on Soils Amended with Sewage Sludge,” Journal of Environmental Quality 4:229–233.

25.Dowdy, R. H., and W. E. Larson (1975), “The Availability of Sludge-Borne Metals to Various Vegetable Crops,” Journal of Environmental Quality 4:278–282.

26.Duncomb, D. R., W. E. Larson, C. E. Clapp, R. H. Dowdy, D. R. Linden, and W. K. Johnson (1982), “Effect of Liquid Wastewater Sludge Application on Crop Yield and Water Quality,” Journal of Water Pollution Control Federation 54:1185–1193.

27.Falahi-Ardakani, A., J. C. Bouwkamp, F. R. Gouin, and R. L. Chaney (1988), “Growth Response and Mineral Uptake of Lettuce and Tomato Transplants Grown in Media Amended with Composted Sewage Sludge,” Journal of Environmental Horticulture 6:130–132.

28.Fresquez, P., R. Francis, and G. Dennis (1990), “Soil and Vegetation Responses to Sewage Sludge on a Degraded Semiarid Broom Snakeweed/Blue Gamma Plant Community,” Journal of Range Management 43(4):325–331.

29.Fresquez, P. R., and W. C. Lindemann (1982), “Soil and Rhizosphere Microorganisms in Amended Mine Spoils,” Soil Science Society Annual Journal 46:751–755.

30.Fresquez, P. R., R. Aguilar, R. E. Francis, and E. F. Aldon (1991), “Heavy Metal Uptake by Blue Gamma Growing in a Degraded Semiarid Soil Amended with Sewage Sludge,” Journal of Water Air and Soil Pollution 57–58:903–912.

31.Fresquez, P. R., R. E. Francis, and G. L. Dennis (1990), “Soil and Vegetation Responses to Sewage Sludge on a Degraded Semiarid Broom Snakeweed/Blue Gamma Plant Community,” Journal of Range Management 43:325–331.

32.Fresquez, P. R., R. E. Francis, and G. L. Dennis (1990), “Effects of Sewage Sludge on Soil and Plant Quality in a Degraded Semiarid Grassland,” Journal of Environmental Quality 19:324–329.

33.Garvey, D., C. Guarino, and R. Davis (1993), “Sludge Disposal Trends Around the Globe,” Water/Engineering & Management, pp. 17–20.

34.Gilmor, J. T., F. Roman, and M. D. Clark (1996), “Decomposition of Biosolids in a Disposal Site Soil,” Journal of Environmental Quality 25:1083–1086.

35.Gilmour, J., and M. Clark (1988), “Nitrogen Release from Wastewater Sludge: A Site-Specific Approach,” Journal of Water Pollution Control Federation 60:494–341.

36.Gouin, F. R., and J. M. Walker (1977), “Deciduous Tree Seedling Response to Nursery Soil Amended with Composted Sewage Sludge,” Horticulture Science 12:45–47.

37.Haug, R. T. (1986), “Composting Process Design Criteria,” Biocycle September 1986:36–39.

38.Hegstrom, L. J., and S. D. West (1989), “Heavy Metal Accumulation in Small Mammals Following Sewage Sludge Application to Forests,” Journal of Environmental Quality 18:345–349.

39.Henry, C. (1991), “Nitrogen Dynamics of Pulp and Paper Sludge to Forest Soils,”

Water Science and Technology, 24:417–425.

40.Henry, C., D. Cole, T. Hinckley, and R. Harrison (1993), “The Use of Municipal and Pulp and Paper Sludges to Increase Production in Forestry,” Journal of Sustainable Forestry 1:41–55.

41.Huddleston, J. H., and M. P. Ronayne (1990), “Guide to Soil Suitability and Site Selection for Beneficial Use of Sewage Sludge,” Oregon State University Extension Service.

42.Jewell, W. J. (1980), “Use and Treatment of Municipal Wastewater and Sludge in Land Reclamation and Biomass Production Projects: An Engineering Assessment,” pp. 448–480 in Utilization of Municipal Wastewater and Sludge: An Engineering Assessment for Land Reclamation and Biomass Production, EPA 430/9-81-012, Washington.

43.Jewell, W. J. (1988), “Anaerobic Sewage Treatment,” Environmental Science and Technology 22:14–21.

44.Keeney, D. (1982), “Nitrogen-Availability Indices,” in Page, A. L. (ed.), Methods of Soil Analysis, Part 2, 2d ed., pp. 711–733, American Society of Agronomy, Madison, Wis.

45.Keeney, D., K. Lee, and L. Walsh (1975), “Guidelines for the Application of Wastewater Sludge to Agricultural Land in Wisconsin,” Technical Bulletin 88, Wisconsin Department of Natural Resources, Madison, Wis.

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Beneficial Use of Biosolids

7.94Chapter Seven

46.Kelling, K. A., A. E. Peterson, L. M. Walsh, J. A. Ryan, and D. R. Keeney (1977), “A Field Study of Agricultural Use of Sewage Sludge: Effect on Crop Yield and Uptake of N and P,” Journal of Environmental Quality 6:339–345.

47.Lance, J. C., and C. P. Gerba (1984), “Virus Movement in Soil During Saturated and Unsaturated Flow,” Applied and Environmental Microbiology 47:335–337.

48.Loehr, R., W. Jewell, J. Novak, W. Clarkson, and G. Friedman (1979), Land Application of Wastes, Vol. 2, Van Nostrand Reinhold, New York.

49.Loehr, R. C. (1977), Land as a Waste Management Alternative, Ann Arbor Science, Ann Arbor, Mich.

50.Logan, T. J., and R. L. Chaney (1983), “Utilization of Municipal Wastewater and Sludge on Land: Metals,” pp. 235–326 in A. L. Page et al. (eds.), Utilization of Municipal Wastewater and Sludge on Land, Univ. of California, Riverside, Calif.

51.Luthin, J. N. (1973), Drainage Engineering, Krieger Publishing Company.

52.Magdoff, F. R., D. Ross, and J. Amadon (1984), “A Soil Test for Nitrogen Availability to Corn,” Soil Science Society of America Journal 48:1301–1304.

53.McNab, W. H., and C. R. Berry (1985), “Distribution of Aboveground Biomass in Three Pine Species Planted on a Devastated Site Amended with Sewage Sludge or Inorganic Fertilizer,” Forest Science 31:373–382.

54.National Association of Conservation Districts (1982), “Sludge and the Land: The Role of Soil and Water Conservation Districts in Land Application of Sewage Sludge,” U.S. Environmental Protection Agency, 430/9-82-007, Washington.

55.National Research Council (1996), “Use of Reclaimed Water and Sludge in Food Crop Production,” National Academy Press, Washington.

56.Ottolenghi, A. C., and V. V. Hamparian (1987), “Multi-year Study of Sludge Application to Farmland: Prevalence of Bacterial Enteric Pathogens and Antibody Status of Farm Families,” Applied and Environmental Microbiology 53:1118–1124.

57.Power, J. F., and J. Alessi (1971), “Nitrogen Fertilization of Semiarid Grasslands: Plant Growth and Soil Mineral Nitrogen Levels,” Journal of Agronomy 63:277–280.

58.Rauzi, F., R. L. Lang, and L. I. Painter (1968), “Effects of Nitrogen Fertilization on Native Rangeland,” Journal of Range Management 21:287–291.

59.Reed, S., R. Crites, and E. Middlebrooks (1994), Natural Systems for Waste Management and Treatment, McGraw-Hill, New York.

60.Roberts, J. A., W. L. Daniels, J. C. Bell, and D. C. Martens (1988), “Tall Fescue Production and Nutrient Status on Southwest Virginia Mine Soils,” Journal of Environmental Quality 17:55–62.

61.Roberts, J. A., W. L. Daniels, J. C. Bell, and J. A. Burger (1988), “Early Stages of Mine Soil Genesis as Affected by Topsoiling and Organic Amendments,” Soil Science Society of America Journal 52:730–738.

62.Roberts, J. A., W. L. Daniels, J. C. Bell, and J. A. Burger (1988), “Early Stages of Mine Soil Genesis in a Southwest Virginia Mine Spoil Lithosequence,” Soil Science Society of America Journal 52:716–723.

63.Sabey, B. R., R. L. Pendleton, and B. L. Webb (1990), “Effect of Municipal Sewage Sludge Application on Growth of Two Reclamation Shrub Species in Copper Mine Spoils,” Journal of Environmental Quality 19:580–586.

64.Seaker, E. M., and W. E. Sopper (1988), “Municipal Sludge for Mine Spoil Reclamation: Effects on Microbial Populations and Activity,” Journal of Environmental Quality 17:591–597.

65.Sloan, J. J., and N. T. Basta (1995), “Remediation of Acid Soils by Using Alkaline Biosolids,” Journal of Environmental Quality 24:1097–1103.

66.Sommers, L. E. (1977), “Chemical Composition of Sewage Sludge and Analysis of Their Potential Use as Fertilizers,” Journal of Environmental Quality 6:225–232.

67.Soon, Y. K., T. E. Bates, and J. R. Moyer (1978), “Land Application of Chemically Treated Sewage Sludge: II. Effects on Plant and Soil Phosphorus, Potassium, Calcium, Magnesium and Soil pH,” Journal of Environmental Quality 7:269–273.

68.Soon, Y. K., T. E. Bates, and J. R. Moyer (1980), “Land Application of Chemically Treated Sewage Sludge: In Effects on Soil and Plant Heavy Metal Content,”

Journal of Environmental Quality 9:497–504.

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Beneficial Use of Biosolids

Beneficial Use of Biosolids

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69.Soon, Y. K., T. E. Bates, E. G. Beauchamp, and J. R. Moyer (1978), “Land Application of Chemically Treated Sewage Sludge: In Effects on Crop Yield and Nitrogen Availability,” Journal of Environmental Quality 7:264–269.

70.Sopper, W. (1993), Municipal Sludge Use in Land Reclamation, Lewis Publishers, Boca Raton, Fla.

71.Sopper, W. E. (1992), “Reclamation of Mined Land Using Municipal Sludge,”

Advances in Soil Science 17:351–431.

72.Sorber, C. A., B. E. Moore, D. E. Johnson, H. J. Hardy, and R. E. Thomas (1984), “Microbiological Aerosols from the Application of Liquid Sludge to Land,” Journal of Water Pollution Control Federation, 56(6).

73.South Carolina Department of Health (1987), Land Application of Sludge Guidance Manual.

74.Stark, S. A., and C. E. Clapp (1980), “Residual Nitrogen Availability from Soils Treated with Sewage Sludge in a Field Experiment,” Journal of Environmental Quality 9:505–512.

75.Tchobanoglous, G. (1991), Wastewater Engineering: Treatment Disposal and Reuse,

3rd ed., McGraw-Hill, New York.

76.U.S. Army Corps of Engineers (1987), “Wetlands Delineation Manual,” Technical Report Y-87-1, Waterways Experiment Station, Vicksburg, Miss.

77.U.S. Department of Agriculture (1994), Sewage Sludge: Land Utilization and the Environment, American Society of Agronomy, Crop Science Society of America, Soil Science Society of America, Washington.

78.U.S. Environmental Protection Agency (1983), “Process Design Manual: Land Application of Municipal Sludge,” EPA/625/1-83/016, Washington.

79.U.S. Environmental Protection Agency (1979), “NPDES Compliance Sampling Manual,” PB81-153215, Washington.

80.U.S. Environmental Protection Agency (1979), “Process Design Manual for Sludge Treatment and Disposal,” EPA/625/1-79/011, Washington.

81.U.S. Environmental Protection Agency (1984), “Handbook: Septage Treatment and Disposal,” EPA/625/6-84/009, Washington.

82.U.S. Environmental Protection Agency (1985), “Handbook Estimating Sludge Management Costs,” EPA-625/6-85010, Washington.

83.U.S. Environmental Protection Agency (1990), “Guidance for Writing Case-by-Case Permit Requirements for Municipal Sewage Sludge,” EPA/505/8-90/001, Washington.

84.U.S. Environmental Protection Agency (1990), “Motor Freight Terminals/Railroad Transportation,” EPA/530/SW-90/027K, Washington.

85.U.S. Environmental Protection Agency (1991), “Cooperative Testing of Municipal Sewage Sludges by the Toxicity Characteristic Leaching Procedure and Compositional Analysis,” EPA 430/09-91-007, Washington.

86.U.S. Environmental Protection Agency (1993), “Domestic Septage Regulatory Guidance—A Guide to The EPA 503 Rule,” EPA/832/B-92/005, Washington.

87.U.S. Environmental Protection Agency (1993), “Preparing Sewage Sludge for Land Application or Surface Disposal: A Guide for Preparers of Sewage Sludge on the Monitoring, Recordkeeping, and Reporting Requirements of the Federal Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503,” EPA/831/B-93/002a, Washington.

88.U.S. Environmental Protection Agency (1993), “Regulatory Impact Analysis of the Part 503 Sewage Sludge Regulation,” EPA/821/R-93/006, Washington.

89.U.S. Environmental Protection Agency (1993), “Standards for Use or Disposal of Sewage Sludge. Final Rule, 40 CFR Part 503,” Federal Register 58(32):9248–9415.

90.U.S. Environmental Protection Agency (1993), “Technical Support Document for Land Application of Sewage Sludge, Vol. I,” PB93-110575; Vol. II, PB93110583, Washington.

91.U.S. Environmental Protection Agency (1993), “Standards for the Use or Disposal of Sewage Sludge,” Federal Register 58(32):9248–9415.

92.U.S. Environmental Protection Agency (1994), “A Plain English Guide to the EPA Part 503 Biosolids Rule,” EPA/832/R-93/003, Washington.

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Beneficial Use of Biosolids

7.96Chapter Seven

93.U.S. Environmental Protection Agency (1994), “Biosolids Recycling: Beneficial Technology for a Better Environment,” EPA/832/R-94/009, Washington.

94.U.S. Environmental Protection Agency (1994), “Guide to Septage Treatment and Disposal,” EPA/625/R-94/002, Washington.

95.U.S. Environmental Protection Agency (1994), “Land Application of Sewage Sludge: A Guide for Land Appliers on the Requirements of the Federal Standards for the Use or Disposal of Sewage Sludge, 40 CFR Part 503,” EPA/831/B-93/002b, Washington.

96.U.S. Environmental Protection Agency (1995), “A Guide to the Biosolids Risk Assessments for the EPA Part 503 Rule,” EPA/832/B-93/005, Washington.

97.U.S. Environmental Protection Agency (1995), “Ground-Water and Leachate Treatment Systems,” EPA/625/R-94/005, Washington.

98.U.S. Environmental Protection Agency (1995), “Part 503 Implementation Guidance,” EPA/833/R-95/001, Washington.

99.U.S. Environmental Protection Agency (1995), “Process Design Manual: Land Application of Sewage Sludge and Domestic Septage,” EPA/625/R-95/001, Washington.

100.U.S. Environmental Protection Agency (1995), “Process Design Manual: Surface Disposal of Sewage Sludge and Domestic Septage,” EPA/625/R-95/002, Washington.

101.U.S. Environmental Protection Agency (1999), “Environmental Regulations and Technology: Control of Pathogens and Vector Attraction in Sewage Sludge,” EPA/625/R-92/013, Washington.

102.Vesilind, P. A., G. C. Hattman, and E. T. Shene (1986), Sludge Management and Disposal for the Practicing Engineer, Lewis Publishers, Boca Raton, Fla.

103.Viessman, W., and M. J. Hammer (1985), Water Supply and Pollution Control, 4th ed., Harper Collins, New York.

104.Weber, W. (1972), Physicochemical Processes for Water Quality Control, Wiley, New York.

105.Wei, Q. F., B. Lowery, and A. E. Peterson (1985), “Effect of Sludge Application on Physical Properties of a Silty Clay Loam Soil,” Journal of Environmental Quality 14:178–180.

106.Whitford, W. G., E. A. Aldon, D. W. Freckman, Y. Steinberger, and L. W. Parker (1989), “Effects of Organic Amendments on Soil Biota on a Degraded Rangeland,”

Journal of Range Management 42:56–60.

107.Yingming, L., and R. B. Corey (1993), “Redistribution of Sludge-Borne Cadmium, Copper, and Zinc in a Cultivated Plot,” Journal of Environmental Quality 2:1–8.

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Source: Biosolids Engineering

Chapter

8

Sampling and

Quality Assurance

8.0 Introduction

Throughout the municipal wastewater industry, the terms sludge and biosolids are often used interchangeably. However, from a regulatory standpoint, only municipal wastewater treatment sludge (including domestic septage) that meets certain quality criteria specified in the 40 CFR Part 503 rule should be designated as biosolids [42,48]. Sludge generated from municipal wastewater treatment operations that does not meet these criteria and/or domestic septage that contains industrial and/or commercial wastes are not considered biosolids.

Sampling is the first step in developing a database to monitor performance or to control processing within a municipal wastewater treatment plant. Within publicly owned treatment works (POTW), both sludge and biosolids are sampled routinely by treatment plant personnel to verify compliance with regulatory limits as well as to evaluate the effectiveness of the various sludge/biosolids processing operations. This chapter provides descriptions of both the general sludge and biosolids sampling procedures typically employed at POTWs and those specific biosolids sampling requirements mandated by the 40 CFR Part 503 rule. Finally, for the management of biosolids beneficial-use operations, descriptions of the general sampling procedures used to monitor the effects of biosolids land-application operations on environmental quality (including soil and vegetation) are provided.

8.1

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Sampling and Quality Assurance

8.2Chapter Eight

8.1 General Sampling of Sludge and

Biosolids

Accurate characterization of sludge/biosolids is required to identify and isolate operational problems at the POTW as well as to signal potential limitations to the use or disposal of biosolids. To the extent practicable, the POTW should have a sludge/biosolids sampling program that adequately addresses the random and cyclic variation in influent wastewater quality and the potential for human exposure to biosolids once they are beneficially used or disposed of [28,29,37].

When developing a sludge/biosolids sampling program, the type of sample to be taken must be selected. In general, the selection of the appropriate sample type is governed by (1) the information sought, (2) the unit process being sampled, (3) the regulatory permit requirements, and (4) the variability of constituents over a period of time. The two types of samples available for sludge/biosolids sampling are the grab and composite samples.

A grab sample (sometimes referred to as an individual discrete sample) is defined as a single sample that is collected at a particular time and location. In the case of sludge/biosolids sampling, single grab samples will represent only the instantaneous composition of the sludge/biosolids being sampled. Although its composition is only reflective of the sludge/biosolids quality at a specific time and location, a grab sample is often required in certain types of sludge/biosolids tests (e.g., estimation of pathogen densities).

A composite sample refers to a mixture of grab samples collected at the same sampling point at different times. The composite sample represents the average conditions of the sludge/biosolids over a particular period of time (typically 24 hours). The analytical results from a composite sample provide a more accurate description of the timeand location-weighted average concentrations present in the sludge/biosolids stream. Examples of sampling situations where a composite sample should be obtained include the following: (1) the average sludge/biosolids conditions must be known for process control, (2) a composite sample is specified in the regulatory permit, or (3) the POTW desires to estimate the treatment plant’s overall pollutant-removal efficiency. It should be noted that although a 24-hour composite sample is often used to establish sludge/biosolids quality, these data are only descriptive of the sludge/biosolids quality for that particular day. Historical data are necessary to accurately establish the long-term trend in sludge/biosolids quality [37].

8.1.1 Representative samples

Obtaining a sludge/biosolids sample that reflects the actual compositional characteristics of a particular stream is termed a representative

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Sampling and Quality Assurance

Sampling and Quality Assurance

8.3

sample. To effectively sample a sludge/biosolids stream, it is necessary for POTW management personnel to be aware of the physical characteristics of the sludge/biosolids that may affect the collection of a representative sample. Some of the physical characteristics of municipal wastewater sludge are described in Table 8.1.

Two physical characteristics of sludge/biosolids that have an impact on the representativeness of a given sample are its solids content and viscosity. The solids content is defined as the percent (by weight) of solid material contained in a given volume of sludge/biosolids [29,30,37]. The sludge/biosolids solids content and the settling behavior that characterizes the solids determine whether a given sample

TABLE 8.1 Physical Characteristics of Various Sludge Types Found at Municipal Wastewater Treatment Plants*

Sludge type

Description

Anaerobically digested sludge

Thick slurry of dark-colored particles and entrained

 

gases. When well digested, anaerobically digested

 

sludge dewaters easily and has a nonoffensive odor.

 

Depending on the mode of operation, the percent

 

solids of anaerobically digested sludges ranges from

 

4 to 8 percent.

Aerobically digested sludge

Aerobically digested sludge is a dark-brown,

 

flocculent, relatively inert suspension produced by

 

long-term aeration of sludge. Aerobically digested

 

sludge is bulky and generally difficult to thicken.

 

The effluent percent sludge solids from aerobic

 

digestion is less than that of the influent sludge

 

percent solids (if not decanted), since approximately

 

50 percent of the volatile solids are converted to

 

gaseous end products.

Dewatered sludge

Dewatering converts liquid sludge from a fluid

 

mixture to a cakelike substance. The specific

 

physical characteristics of the dewatered sludge

 

depend on the type of sludge, chemical conditioning,

 

and treatment processes employed. The percent

 

solids content of a dewatered cake ranges from

 

approximately 15 to 50 percent.

Composted sludge

Composting is a process in which the organic

 

material in dewatered sludge undergoes biologic

 

degradation to a stable endproduct. Properly

 

composted sludge is a humuslike material

 

containing 75 to 80 percent solids.

Dried powdered sludge

Dried powdered sludge is the residue from heat

 

drying processes. Sludge drying reduces the

 

sludge’s moisture content by vaporization. The

 

moisture content of dried powdered sludge is less

 

than 10 percent.

 

 

*Adapted from ref. [37].

 

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Sampling and Quality Assurance

8.4Chapter Eight

will separate (i.e., stratify) into various fractions under normal sampling conditions.

In addition to affecting sludge/biosolids sampling, the sludge solids content also affects the accuracy and precision of some analytical measurements. For example, in measuring pathogen densities, a sludge/biosolids sample with a relatively high solids content normally requires dilution prior to analysis, a preparation step that can lead to an increase in experimental error. Similarly, when attempting to quantify the toxic organic compounds or heavy metal concentrations in sludge/biosolids, analytical precision and accuracy may be adversely affected when analyzing samples with a high solids content due to interfering compounds and/or matrix effects.

Viscosity is defined as the characteristic of a material that causes it to resist flow when subjected to an applied force (e.g., pumping action) [37]. The importance of viscosity in sludge/biosolids sampling stems from the use of certain types of automatic liquid sampling equipment. In general, automatic sampling devices that rely on a vacuum lift to withdraw a sample can be employed for continuous sampling if the sludge/biosolids has a solids content of less than 15 percent. Although these types of systems have been employed for sampling sludge/biosolids flows containing higher concentrations of solids, their application in these situations has proven to be unreliable [37]. For sampling sludges/biosolids with a solids content greater than 15 percent, manual sampling equipment is recommended (Fig. 8.1).

8.1.2 Composite sample development

To develop a composite sample whose compositional characteristics reflect the actual sludge/biosolids conditions, accurate volumetric flow (i.e., gallons per day) and/or solids flux (i.e., pounds per day) data must be obtained. Although volumetric flow data can be developed for a liquid sludge/biosolids flow by installing a reliable flowmeter, obtaining solids flux for liquid sludge/biosolids flow requires having information on both the volumetric flow and the average solids content. Given the availability of accurate flow and solids content data, Eq. (8.1) may be used to estimate an average solids flux for a liquid sludge/biosolids flow stream:

Solids flux (lb solids/day)

average flow rate (MG/day) solids concentration (mg/liter)

8.34 lb/MG (mg/liter)

(8.1)

where MG/day is million gallons per day.

For a solid or semisolid sludge/biosolids flow, the solids flux may be estimated using appropriately sized industrial equipment scales.

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Sampling and Quality Assurance

Sampling and Quality Assurance

8.5

Figure 8.1 Photograph of a wastewater treatment operator taking a dewatered biosolids/sludge sample. (Courtesy of the Water Environment Federation.)

Solids flux data from industrial weighing scales normally are corrected to a dry-mass basis by accounting for the average moisture content of the sludge/biosolids flow. Table 8.2 summarizes the types of measurement equipment typically employed to estimate both the volumetric flow and solids flux rates of sludge/biosolids flows.

Having accurate volumetric flow or solids flux data is particularly important when developing a sampling plan for a sludge/biosolids treatment process in which several streams are either entering or leaving the unit operation. To determine the average condition of a set of multiple sludge/biosolids streams, a composite sample that reflects the compositional characteristics for the confluent sludge stream is developed by taking grab samples from each individual stream. Several alternative approaches exist to generate an accurate composite sample for multiple sludge streams (Table 8.3). Example 8.1 illustrates the application of volumetric flow and solids flux data in preparing a composite sludge/biosolids sample.

Example 8.1 The Rogers County Wastewater Treatment Plant has two anaerobic digesters operating in parallel that discharge their treated effluent to a common drying bed for dewatering. The sludge management personnel desire to develop a 1-gal composite sample that characterizes the average conditions of the combined effluent from both anaerobic digesters. If the first digester (digester A) has an average daily flow rate of 4620

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Sampling and Quality Assurance

8.6Chapter Eight

TABLE 8.2 Flow-Measuring Devices

Sludge type

Measurement device: type of measurement

Stabilized liquid sludge

Venturi meter: volumetric flow rate

 

Flow-tube meter: volumetric flow rate

 

Magnetic meter: volumetric flow rate

 

Positive-displacement pump: volumetric flow rate

 

 

Thickened sludge

Magnetic meter: volumetric flow rate

 

Positive-displacement pump: volumetric flow rate

 

 

Dewatered sludge

Belt press scales: solids flux rate

 

 

Dried sludge

Bulk container or truck scales: solids flux rate

Composted sludge

 

Thermally reduced sludge

 

 

 

*Adapted from refs. [28,29,37].

TABLE 8.3 Alternatives for Sampling Multiple Sludge Streams*

Alternative The simplest alternative for sampling multiple sludge streams is to

1withdraw equal volumes of samples from each of the multiple sludge streams to create a composite sample. This approach is justified in the case of multiple sludge/biosolids streams having identical volumetric flow rates and solids content. In the municipal wastewater industry, this type of composite sampling approach is often called a fixed-volume composite sample.

Alternative A second alternative for sampling multiple sludge streams is to generate

2a composite sample by taking grab samples from each sludge flow. In this approach, the size of each grab sample is proportional to the volumetric flow rate of each sludge stream. In the municipal wastewater industry, this type of sample is called a flow-proportioned composite sample. This approach to composite sampling can only be used if accurate volumetric flow data exist.

Alternative The final alternative for sampling multiple sludge streams is to generate

3a composite sample by taking grab samples from each sludge flow. The size of each grab sample should be proportional to the solids flux (lb solids/day) of each sludge stream. In the municipal wastewater industry, this type of sample is called a solids-proportioned composite sample. To employ this sampling approach, the average solids concentration and volumetric flow rate for each sludge stream must be estimated. These parameters can be used to estimate the average solids flux for each sludge/biosolids stream using Eq. (8.1).

*Adapted from ref. [37].

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