Biosolids Engineering - Michael McFarland.pdf - ksiazki w pdf - shaerogorath

Source: Biosolids Engineering

Biosolids Management

Practices and

Regulatory Requirements

1.0 Introduction

In 1948, the U.S. Congress enacted the original Federal Water Pollu-

tion Control Act (FWPCA). Since its passage, the FWPCA has been

amended many times. Two of the most important amendments were

(1) the 1972 FWPCA Amendments and (2) the 1977 Clean Water Act

Amendments [10]. These amendments define the basic national frame-

work for water quality and water pollution control in the United

States. Today, the comprehensive federal law is simply referred to as

the U.S. Clean Water Act (CWA).

The primary objective of the CWA is to restore and maintain the

chemical, physical, and biological integrity of the nation’s waters. To

prevent contamination and deterioration of water quality, wastewater

from industrial, commercial, and residential activities is treated at

wastewater treatment plants (WWTPs) before it is discharged to sur-

face water or groundwater (Fig. 1.1).

At present, there are more than 15,000 municipal wastewater treat-

ment plants or publicly owned treatment works (POTWs) in the

United States that process over 34 billion gallons of domestic sewage

and other wastewater each day [21]. Sewage sludge represents the

largest source of residual solids generated during the treatment of

municipal wastewater by POTWs as well as by privately and federally

1.1

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Chapter

Biosolids Management Practices and Regulatory Requirements

1.2

Chapter One

Figure 1.1 Aerial view of typical municipal wastewater treatment plant

(WWTP). ( Courtesy of Waterlink, Inc. )

owned wastewater treatment works. The annual amount of sewage

sludge (i.e., biosolids) generated during the treatment of domestic

sewage is estimated at approximately 47 pounds for every individual

in the United States. Figure 1.2 illustrates the collection and treat-

ment of domestic and industrial wastewater resulting in the produc-

tion, treatment, use, and disposal of sewage sludge.

In the United States, the use or disposal of sewage sludge has been

regulated under various federal environmental statutes. Land dispos-

al and reuse of sewage sludge were regulated initially under the solid

waste disposal regulations of 40 Code of Federal Regulations (CFR)

Part 257, which was jointly promulgated under the 1976 Resource

Conservation and Recovery Act (RCRA) and Sections 405 and 307 of

the 1977 CWA Amendments. RCRA (PL 94-580) required that solid

wastes be used or disposed in a safe and environmentally acceptable

manner. Sewage sludge was included by definition in the RCRA provi-

sions relating to solid waste management. The 1977 CWA

Amendments (PL 95-217) contained two major provisions affecting

sewage sludge use and disposal. First, Section 405 of the 1977 CWA

Amendments required that the U.S. Environmental Protection Agency

(USEPA) issue guidelines and regulations for the disposal and reuse of

sewage sludge. Second, Section 307 of the CWA Amendments required

pretreatment of industrial wastes if such wastes, when discharged

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Biosolids Management Practices and Regulatory Requirements

Management Practices and Regulatory Requirements

1.3

Figure 1.2 Schematic illustration of the generation, treatment, use, and disposal of

sewage sludge.

into municipal sewage collection systems, inhibited wastewater treat-

ment or the beneficial use of sewage sludge. In addition to RCRA and

the CWA Amendments, the 1972 Marine Protection, Research and

Sanctuaries Act (MPRSA) regulated the discharging of sewage sludge

to oceans and estuaries until the Ocean Dumping Ban Act of 1988 pro-

hibited this disposal practice [10].

In 1987, Section 405(d) of the CWA was amended to require the

USEPA to establish sewage sludge pollutant standards that adequate-

ly protected public health and the environment from any reasonably

anticipated adverse effects of pollutants in sewage sludge that is used

or disposed [21]. These regulations were to include identification of the

various beneficial uses for sludge while specifying factors to be taken

into account in developing management practices for each type of

reuse or disposal option. The 1987 CWA Amendments also required

that any CWA Section 402 (National Pollutant Discharge Elimination

System, NPDES) permit include sewage sludge use or disposal stan-

dards unless these requirements were included in another permit. The

1987 CWA Amendments expanded the regulated universe to include

all treatment works treating domestic sewage (TWTDS), even those

not requiring an NPDES permit. TWTDS include all sewage sludge or

wastewater treatment systems used to store, treat, recycle, and

reclaim municipal or domestic sewage.

In summary, to maintain regulatory compliance with the CWA

requirements, POTWs must adopt and implement federally mandated

procedures ensuring the proper treatment, use, and disposal of sewage

sludge. Furthermore, as a result of Section 405 of the 1977 and 1987

CWA Amendments, increased use of sewage sludge recycling has

become a clear objective of U.S. environmental policy.

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Biosolids Management Practices and Regulatory Requirements

1.4

Chapter One

1.0.1 Summary statistics for sewage

sludge use and disposal in the

United States

In 1988, the USEPA collected information on the use or disposal of

sewage sludge through a two-part National Sewage Sludge Survey

(NSSS). In Part I, a questionnaire survey was used to obtain both tech-

nical and financial information on the sewage sludge use or disposal

practices employed by POTWs. In Part II, information on the quality of

sewage sludge was obtained by analyzing sewage sludge from several

POTWs for specific pollutants. Results from the NSSS were used as the

basis for establishing several of the sewage sludge pollutant limits

found in the 40 CFR Part 503 sludge rule (see Sec. 1.1). The number of

POTWs and the magnitude of sewage sludge generated (dry-mass

basis) as reported in the 1988 NSSS are sumarized in Table 1.1.

In 1988, POTWs with a design flow rate of over 100 million gallons

per day (MGD) accounted for 30.1 percent of the sewage sludge used

or disposed by POTWs. POTWs with a design flow rate of between 10

and 100 MGD used or disposed 38.4 percent of the total annual

amount of sewage sludge generated in the United States, while

POTWs with a flow rate of between 1 and 10 MGD used or disposed

24.0 percent of the sewage sludge. In contrast, while they account for

more than half of all POTWs in the United States, POTWs with a flow

rate of less than 1 MGD generated only 7.5 percent of the annual

amount of sewage sludge used or disposed.

The 1988 NSSS identified four principal categories of practices

employed by POTWs for the reuse and or disposal of sewage sludge.

Table 1.2 illustrates that, in 1988, the most prevalent sludge reuse/dis-

posal practice was land application (34.6 percent), followed by sewage

sludge codisposal in municipal solid waste landfills. With respect to

the total mass of sewage sludge generated, codisposal in municipal

landfills was the preferred disposal practice in 1988, accounting for

33.7 percent of the total amount of sludge generated.

TABLE 1.1 Number of Publicly Owned Treatment Works (POTWs), Actual Flow,

and Estimated Sewage Sludge Quantities in the United States*

POTW flow rate

Quantity of sewage sludge

(MGD)†

No. of POTWs

(dmt)‡

Percent

100

2,120,512

30.1

10 –100

459

2,709,604

38.4

1–10

2,666

1,692,086

24.0

9,588

530,339

7.5

TOTAL

12,748

7,052,540

100.0

*Adapted from ref. [18].

†MGD, million gallons per day.

‡dmt, dry metric ton (1000 kg) = 0.9072

U.S. ton. (kg = 2.2 lb.)

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Biosolids Management Practices and Regulatory Requirements

Management Practices and Regulatory Requirements

1.5

TABLE 1.2 Use and Disposal Practices of Sewage Sludge in the United States*

Percentage of POTWs

Percentage of total

Use/disposal practice

using a particular practice

sewage sludge generated

Land application

34.6

33.5

Codisposal landfill

22.2

33.7

Incineration

2.8

16.1

Surface disposal

10.1

10.4

Unknown transfers

30.3

6.3†

*Adapted from refs. [21,23].

† Ocean disposal— banned in 1988.

Due to the increased level to which municipal wastewater is now

required to be treated, it is anticipated that the sewage sludge vol-

umes have increased significantly since 1988. Some of the regulatory

requirements that have mandated higher levels of wastewater treat-

ment include (1) the reduction in permissible levels of nitrogen and

phosphorus in wastewater discharges to surface waters and (2) the

conversion of primary treatment-only facilities to full secondary treat-

ment [21]. In addition to the increased stringency in federal and local

water quality discharge standards, industrial pretreatment programs

have had a significant impact on sewage sludge management. With

the overall improvement in sewage sludge quality as a result of imple-

mentation of industrial pretreatment programs, a large volume of

sewage sludge can now be directed toward beneficial use, such as land

application and the production and sale of sewage sludge amendment

products (e.g., compost, heat-dried pellets, alkaline-stabilized soil

additives, and soil substitute products). To document the impact of

changing water quality standards on sewage sludge quality and gen-

eration rates, the USEPA is currently developing the scope for a sec-

ond national sewage sludge survey [2,3].

Although regulatory compliance issues have led to consideration of

new approaches to sewage sludge recycling, in some cases, rising trans-

portation and labor costs have stimulated changes in sewage sludge

management. For example, wastewater treatment authorities recently

have been faced with dramatic increases in sewage sludge disposal

costs. In the 1970s, costs for sewage sludge disposal generally were less

than $100 per dry ton, whereas recent short-term private contracts to

implement land-based sewage sludge disposal alternatives have been

reported to be as high as $800 per dry ton [23]. Such increases in dis-

posal costs, along with the difficulties in siting sewage sludge disposal

facilities, have led to situations where long-distance sewage sludge

transport becomes necessary (e.g., New York City sewage sludge trans-

ported to Arizona for reuse/disposal). With such high sewage sludge

management costs, more attention is being paid to the development and

implementation of innovative approaches to sewage sludge recycling.

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