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Biosolids Engineering - Michael McFarland

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Biosolids Management Practices and Regulatory Requirements

Management Practices and Regulatory Requirements

1.101

TABLE 1.34 Risk-Specific Concentrations for Chromium Based on Incinerator System*

Chromium

RSC ( g/m3)

Fluidized bed with wet scrubber

0.650

Fluidized bed with wet scrubber and wet electrostatic precipitator

0.230

Other types of wet scrubbers

0.064

Other types of wet scrubbers and wet electrostatic precipitators

0.016

 

 

*Adapted from refs. [21,22,30].

will be in violation of the 40 CFR Part 503 (Subpart E) rule until system adjustments are made that allow the limits to be met. Such system adjustments include, but are not limited to, improvements in biosolids quality through pretreatment (see Chap. 4), reduction in the biosolids feed rate, improved furnace operation, or addition of an air pollution control device to improve pollutant control efficiency. It should be noted that if furnace or air pollution control device improvements are made, the performance test used to establish the pollutant control efficiency must be repeated and documented for the permitting authority.

In addition to pollutant limits, the USEPA established operational standards for certain pollutants included in the exhaust gases. The pollutants that are regulated in the exhaust gases include beryllium, mercury, and total hydrocarbons (or carbon monoxide). The following sections describe the regulatory framework used to establish the permissible pollutant emission levels in the exhaust gases.

Example 1.8 The Baldwin County Water Reclamation Facility (see Example 1.7) has scheduled to bring its biosolids incinerator system on line within 90 days. From performance tests on the fluidized-bed incinerator system, the wet scrubbers used to treat the exhaust gas have been found to have a pollutant control efficiency of 98 percent for all regulated pollutants. If the biosolids feed rate is 700 dmt/day and the dispersion factor is 3.5 g/m3 g s, estimate the biosolid pollutant limits for lead, arsenic, cadmium, nickel, and chromium. Assume that the current NAAQS for lead is 1.5 g/m3.

solution

Step 1. Estimate the pollutant limit for lead using Eq. (1.6).

0.1 NAAQS 86,400

 

Clead

 

DF (1 CE)

SF

 

0.1 (1.5 g/m3) 86,400

 

 

3.5 g

(1

700 dmt

 

 

0.98)

m3 g s

 

day

264.5 mg

 

 

 

 

 

 

 

kg

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Biosolids Management Practices and Regulatory Requirements

1.102 Chapter One

Step 2. Estimate the pollutant limit for arsenic, cadmium, and nickel using Eq. (1.7) and Table 1.33. From Table 1.33, the RSCs for arsenic, cadmium, and nickel are 0.023, 0.057, and 2.000, respectively.

Carsenic

RCS 86,400

 

 

 

 

 

 

 

DF (1 CD)

SF

 

 

 

0.023 86,400

 

 

 

 

3.5 g

(1

700 dmt

 

 

 

0.98)

 

m3 g s

 

 

day

 

40.6 mg

 

 

 

 

 

 

 

 

 

 

 

 

kg

 

 

 

 

 

Ccadmium

RCS 86,400

 

 

 

 

 

 

DF (1 CE)

SF

 

 

 

 

0.057 86,400

 

 

 

 

3.5 g

 

 

700 dmt

 

 

 

 

(1 0.98)

 

m3 g s

 

day

 

 

100.5 mg

 

 

 

 

 

 

 

 

 

 

 

 

kg

 

 

 

 

 

 

RCS 86,400

 

 

Cnickel

 

 

 

DF (1 CE)

SF

 

 

 

 

2.000 86,400

 

 

 

 

3.5 g

 

 

700 dmt

 

 

 

 

(1 0.98)

 

m3 g s

 

day

 

 

3526.3 mg

 

 

 

 

 

 

 

 

 

 

 

 

kg

 

 

 

 

 

Step 3. Estimate the pollutant limit chromium using the RSC for a flu- idized-bed incinerator equipped from a wet scrubber. From Table 1.34, the RSC for chromium is 0.65.

 

RCS 86,400

 

 

Cchromium

 

 

DF (1 CE)

SF

 

 

0.65 86,400

 

 

 

3.5 g

(1

700 dmt

 

 

 

0.98)

 

m3 g s

 

day

 

1146.1 mg

 

 

 

 

 

 

 

 

kg

 

 

 

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Biosolids Management Practices and Regulatory Requirements

Management Practices and Regulatory Requirements

1.103

1.4.6.3Emission limits for beryllium and mercury. The emission limits for beryllium and mercury contained in a biosolids incinerator exhaust gas are based on the National Emission Standards for Hazardous Air Pollutants (NESHAP) for incineration (40 CFR Part 61). The NESHAP for beryllium requires that the total quantity of beryllium emitted from a biosolids incinerator not exceed 10 g during any 24-hour period. The NESHAP emission limitation for beryllium can be waived if written approval has been obtained from the USEPA regional administrator, which may occur if (1) the ambient beryllium concentration in the proximity of the biosolids incinerator does not exceed 0.01 g/m3 when averaged over a 30-day period or (2) if the biosolids incinerator operator can demonstrate (with historical data) that the biosolids fired in the incinerator do not contain beryllium [21,22,24,30]. The NESHAP emission limitation for mercury requires that the total quantity of mercury emitted from each biosolids incinerator not exceed 3200 g during any 24-hour period [22,24,30].

1.4.6.4Emission limits for total hydrocarbons and carbon monoxide.

Organic compounds that are generated as a result of incomplete combustion or are produced as combustion by-products (e.g., benzene, phenol, vinyl chloride, etc.) can be present in biosolids incinerator emissions. Since these compounds can be harmful to public health, the 40 CFR Part 503 (Subpart E) rule limits the emission of total hydrocarbons (THCs) in the exhaust gases from biosolids incinerators. As an alternative approach for ensuring that the THC emission limits will be met, the USEPA has allowed the monitoring of carbon monoxide (CO) in the exhaust gas as a surrogate measurement for total hydrocarbons [24,30].

To be in compliance with the 40 CFR Part 503 rule, the maximum monthly average concentration of THCs (or CO) in the exhaust gas from a biosolids incinerator can be no greater than 100 parts per million (volume basis, ppmv). The 40 CFR Part 503 rule defines the monthly average THC (or CO) concentration as the arithmetic mean of the hourly pollutant measurement averages, each of which must be calculated based on at least two readings taken each hour that the incinerator operates [22,30]. In addition to the number of exhaust air samples that must be taken, the 40 CFR Part 503 rule specifies that the THC (or CO) concentration must be measured using a flame ionization detector (FID) with a sampling line heated to at least 150°C (300°F) (which minimizes pollutant condensation).

It should be noted that certain incinerator operational conditions will affect the THC (or CO) measurement. The two primary incinerator operational conditions that affect the THC (or CO) measurement

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Biosolids Management Practices and Regulatory Requirements

1.104 Chapter One

are (1) feed biosolids moisture content and (2) excess airflow rates. To account for the effects of these incinerator operational conditions (as well as others) on the exhaust gas pollutant measurements, the USEPA requires that the measured THC (or CO) concentration be corrected to 0 percent moisture and 7 percent oxygen content before being compared with the 100-ppmv regulatory limit.

To correct the THC (or CO) exhaust gas concentrations to 0 percent moisture, Eq. (1.9) may be used, while THC (or CO) measurements may be normalized to 7 percent oxygen using Eq. (1.10). Example 1.9 illustrates the approach for standardizing the THC (or CO) stack measurements to the requisite regulatory conditions necessary for compliance verification.

 

1

(1.9)

Correction factormoisture

1

X

 

where X decimal fraction of percent moisture in the stack gas

14

(1.10)

Correction factoroxygen

21 Y

 

where 14 difference between percent oxygen in air (i.e., 21 percent) and 7 percent oxygen

21 percent oxygen in air

Y percent oxygen concentration in incinerator exhaust gas (volume/volume)

Example 1.9 The Baldwin County Water Reclamation Facility (see Example 1.7) has opted to monitor carbon monoxide as a surrogate for total hydrocarbons (THCs). If the measured monthly average CO concentration for each of the four incinerators is 23 ppmv (unit I), 72 ppmv (unit II), 49 ppmv (unit III), and 84 ppmv (unit IV), determine the compliance status of each of the units. Assume that the average moisture and oxygen contents of the exhaust gas of each unit are 15 and 10 percent, respectively.

solution

Step 1. Estimate the moisture and oxygen correction factors using Eqs. (1.9) and (1.10), respectively.

 

1

1

1.1765

Correction factormoisture

 

 

1 X

1 0.15

 

Correction factoroxygen

14

14

 

1.2727

 

21 Y

21 10

 

Step 2. Multiply each of the carbon dioxide stack measurements by both the moisture and oxygen correction factors to obtain the regulatory measurement.

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Biosolids Management Practices and Regulatory Requirements

Management Practices and Regulatory Requirements

1.105

Unit I:

Regulatory CO measurement

stack measurement correction factormoisture correction factoroxygen

23 ppm 1.1765 1.2727

34.4 ppm

Unit II:

Regulatory CO measurement

stack measurement correction factormoisture correction factoroxygen

72 ppm 1.1765 1.2727

107.8 ppm

Unit III:

Regulatory CO measurement

stack measurement correction factormoisture correction factoroxygen

49 ppm 1.1765 1.2727

73.4 ppm

Unit VI:

Regulatory CO measurement

stack measurement correction factormoisture correction factoroxygen

84 ppm 1.1765 1.2727

125.8 ppm

NOTE: Incinerators II and IV are out of compliance with the 40 CFR Part 503 (Subpart E) rule.

It should be noted that if the normalized monthly average THC (or CO) concentration were found to be above 100 ppmv, the biosolids incinerator would be in violation of the 40 CFR Part 503 (Subpart E) rule until adjustments are made to achieve the regulatory limits (typical adjustments include altering the furnace temperature and/or improving the pollutant control efficiency).

1.4.7 Management practices for biosolids incineration

The 40 CFR Part 503 rule specifies several management practices that must be followed to legally operate a biosolids incinerator.

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Biosolids Management Practices and Regulatory Requirements

1.106 Chapter One

Management practices include (1) instrument operation and maintenance, (2) temperature requirements, (3) operation of air pollution control devices, and (4) protection of threatened or endangered species.

Biosolids incinerator operators must use instruments to continuously measure and record certain information, including (1) THCs (or CO) in the exhaust gas, (2) oxygen content in the exhaust gas, (3) information used to calculate moisture content of the exhaust gas, and (4) furnace combustion temperatures. Biosolids management practices require that each of the instruments used for these measurements be installed, calibrated, operated, and maintained according to guidance provided by the permitting authority. Examples of instruments used to monitor the incineration process include (1) flame ionization detector (FID, for measurement of THCs or CO), (2) extractive or in situ oxygen analyzers (for O2 measurement in exhaust gas), (3) thermocouples (temperature measurements), and (4) dew point detectors (for moisture content estimation of exhaust gas). In addition to using an FID, management practices require that the THC (or CO) monitoring system employ a sampling line heated to at least 150°C (300°F) and that the FID detector be calibrated using propane at least once every 24hour operating period [24,30].

1.4.7.1Temperature requirements. Because of its impact on both the pollutant control efficiency and auxiliary fuel requirements, incinerator temperature is a critical system operational parameter. The permitting authority, based on performance test data, establishes the maximum combustion temperature allowed in the incinerator furnace. A limit on combustion temperature is necessary to ensure that the daily performance of the incinerator is similar to what was recorded during the performance test. If biosolids were incinerated at higher temperatures than those recorded during the performance test, the pollutant control efficiency may be significantly different during normal operation.

1.4.7.2Air pollution control devices. In addition to the maximum combustion temperature, the regulatory authority is responsible for determining the permissible operational conditions for any air pollution control device treating exhaust gases from the biosolids incinerator. The range of acceptable values for the operational parameters (e.g., liquid flow rate, pressure drop, temperature, etc.) is determined by the permitting authority using data obtained during the system performance test. The operational conditions are established to ensure that the air pollution control device will achieve the desired level of pollutant control efficiency. Examples of operational parameters that are

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Biosolids Management Practices and Regulatory Requirements

 

Management Practices and Regulatory Requirements

1.107

TABLE 1.35 Operational Parameters for Air Pollution Control Devices*

 

 

 

 

Operational parameter

Air pollution control device

Measuring instrument

 

 

 

Pressure drop

Venturi scrubber

Differential pressure

 

Fabric filter

gauge

 

 

Mist eliminator

 

 

 

Impingement scrubber

 

 

Liquid flow rate

Venturi scrubber

Orifice plate with

 

 

Impingement scrubber

differential pressure

 

Wet electrostatic precipitator

gauge

 

Gas temperature

Venturi scrubber

Thermocouple

 

 

Impingement scrubber

 

 

 

Fabric filter

 

 

 

Dry scrubber

 

 

Compressed air pressure

Dry scrubber

Pressure gauge

 

Opacity

Fabric filter

Transmissometer

 

Liquid/reagent flow

Dry scrubber

Magnetic flowmeter

Atomized motor power

Dry scrubber

Wattmeter

 

 

 

 

 

*Adapted from refs. [24,30].

typically used to control the performance of air pollution control devices are summarized in Table 1.35.

1.4.7.3 Protection of threatened or endangered species. The 40 CFR Part 503 (Subpart E) rule does not allow biosolids to be incinerated if a threatened or endangered animal or plant species or its “critical habitat” is likely to be adversely affected. Critical habitat is defined as any place where a threatened or endangered species lives and grows during any stage of its life cycle [21,24,30]. Any direct or indirect action (or the result of any direct or indirect action) in a critical habitat that diminishes the likelihood of survival and recovery of a listed species is considered destructive of a critical habitat [24]. A list of endangered and threatened species is published annually by the U.S. Fish and Wildlife Service as mandated by the Endangered Species Act (PL 99-625). Specific regulations pertaining to the protection of endangered and threatened plants and animals may be found in 50 CFR Part 17 [21].

1.4.8 Monitoring frequency

The owner/operator of a biosolids incinerator must monitor at specified intervals for various biosolids quality parameters as well as pollutants in incinerator emissions. A summary of these monitoring requirements is provided in Table 1.36.

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Biosolids Management Practices and Regulatory Requirements

1.108 Chapter One

TABLE 1.36 Parameters That Must Be Monitored during Biosolids Incineration*

1.Concentration of metals in biosolids (arsenic, cadmium, chromium, lead, and nickel)

2.Concentration of beryllium and mercury in exhaust gas

3.Concentration of THCs (or CO) in exhaust gas

4.Concentration of oxygen in exhaust gas

5.Moisture content of exhaust gas

6.Combustion temperature in the furnace

7.Operating conditions of the air pollution control device

8.Biosolids feed rate

*Adapted from refs. [24,30].

For the regulated metals contained in feed biosolids (i.e., arsenic, cadmium, chromium, lead, and nickel), the minimum frequency for monitoring is based on the amount of biosolids incinerated. POTWs incinerating zero to less than 290 dry metric tons (dmt) annually must test for these metals once per year. Those POTWs incinerating 290 to less than 1500 dmt of biosolids per year must evaluate for these metals in biosolids once per quarter, whereas POTWs incinerating 1500 to less than 15,000 dmt of biosolids per year must test for these metals once every 60 days. POTWs incinerating 15,000 dmt or more of biosolids must evaluate for the concentration of these metals once per month.

Continuous emissions monitoring (CEM) of the exhaust gas is required to quantify the (1) THC (or CO) concentration, (2) oxygen content, and (3) moisture content. CEM is also required for ensuring that the combustion temperature in the furnace remains within the permissible range. In addition, the permitting authority typically requires that certain operating conditions of air pollution control devices be monitored routinely. The specific parameters that must be monitored are based on the type of air pollution control device used and the operating parameters that are important for maintaining the established pollutant control efficiency. Finally, the permitting authority will determine how often the facility operator must monitor for beryllium and mercury in the exhaust gas.

1.4.9 Recordkeeping

The owner/operator of the biosolids incinerator must develop and maintain certain records for a minimum of 5 years. The recordkeeping requirements, which include information on the pollutant limits, management practices, and monitoring requirements, are summarized in Table 1.37.

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Biosolids Management Practices and Regulatory Requirements

Management Practices and Regulatory Requirements

1.109

TABLE 1.37 Records That Must Be Kept by Owner/Operator of Biosolids Incinerator for 5 Years*

1.The concentrations of arsenic, chromium, cadmium, lead, and nickel in the biosolids fed to the incinerator.

2.The concentrations of THCs, moisture, and oxygen in the exhaust gases and information used to measure these parameters.

3.Information indicating that the beryllium and mercury emission limits specified in 40 CFR Part 61 are met.

4.Combustion temperature range including the maximum temperature as set by the permitting authority.

5.Operating parameter values for the air pollution control device.

6.The biosolids feed rate for each incinerator.

7.The stack height and dispersion factor for the site.

8.The pollutant control efficiency for lead, arsenic, cadmium, chromium, and nickel.

9.The risk specific concentration (RSC) for chromium, if calculated.

10.A calibration and maintenance log for monitors used to measure the combustion temperature, THC concentration, oxygen concentration, and moisture content.

*Adapted from refs. [24,30].

1.4.10 Reporting requirements

All Class I treatment works, treatment works serving a population of 10,000 or more, and treatment works with a 1 million gallon per day (1 MGD) or greater design wastewater influent flow must report the following information to the permitting authority: (1) pollutant concentration in biosolids fired to the incinerator, (2) THCs (or CO) in exhaust gas, (3) oxygen and moisture contents of exhaust gas, (4) mercury and beryllium emission data, (5) furnace combustion temperature, and (6) operational data for the air pollution control device(s). POTW reporting information must be submitted to the permitting authority in an annual report, which is due by February 19 of the following calendar year.

1.4.11 USEPA Biosolids Data Management

System

Although the 40 CFR Part 503 rule requires all Class I facilities to submit biosolids annual reports, the USEPA currently does not have a centralized database to collect and review the data quality. The Biosolids Data Management System (BDMS), which has been developed by the USEPA (Region VIII), will be employed for assessing the quality of biosolids data collected throughout the United States. The BDMS is basically an electronic file cabinet designed for the storage

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Biosolids Management Practices and Regulatory Requirements

1.110 Chapter One

and retrieval of biosolids management data. The system enables the user to store, search, retrieve, and review all information necessary to determine a facility’s compliance status. BDMS allows the user to identify discrepancies in the data submitted by facilities with its errorchecking capabilities. With the data in the BDMS, biosolids quality together with the compliance status of biosolids management systems can be evaluated within a state, USEPA region, or across the United States. By increasing access to biosolids data, it is anticipated that public confidence in the biosolids program will increase.

The BDMS consists of nine active databases and ten libraries [5]. The active databases include (1) general facilities information (e.g., point of contact, addresses, phone numbers), (2) biosolids treatment provided, (3) use/disposal method, (4) land-application site information, (5) cumulative loading tracking, (6) monitoring data (yearly averages and maximums), (7) monitoring data tracking (individual data points), (8) pathogen reduction and vector attraction reduction, and (9) findings. The libraries are a repository for the data that are common to all databases.

1.4.12 Criticisms of the 40 CFR Part 503 rule

The 40 CFR Part 503 rule has provided a set of risk-based and/or operational standards designed to promote regulatory uniformity for biosolids beneficial use. Although some critics have argued that the 40 CFR Part 503 rule is unnecessarily restrictive, most published criticisms have focused on claims of inadequate protection of public health and the environment [6]. The majority of complaints regarding the 40 CFR Part 503 rule fall into one of the following three categories: (1) alternative protection paradigms, (2) unaddressed issues, or (3) methodologic arguments.

Paradigm-based criticisms reflect the fact that an individual or organization has a fundamentally different philosophical approach to biosolids recycling than does the USEPA. An example of an alternative protection paradigm is exemplified by the policy-formulated regulations of some European countries, which are based on soil-protection goals that balance soil metal inputs and losses. This approach to establishing biosolids land-application rates would result in numerical soil loadings that are significantly more restrictive than the 40 CFR Part 503 rule [2,3].

With regard to unaddressed issues, most objections of the 40 CFR Part 503 rule have focused on the additive effects of metals relative to phytotoxicity and/or pathogen regrowth in stored biosolids. In addition, there have been criticisms pertaining to the existence of unregulated contaminants in biosolids that may pose a significant human

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