Michael E. Norman, Sunil Kapoor, G. Allan Smalley Jr.
ENSR Consulting & Engineering
Houston
Bruce M. Daniel
ENSR Consulting & Engineering
Redmond, Wash.
Since 1990, the refining industry's focus has been primarily on the difficulty and cost of complying with new Clean Air Act regulations. This focus sometimes overlooks new and anticipated regulatory requirements for wastewater, which will rival air regulations in cost and complexity.
In 2-5 Nears, many refineries will have to almost totally reconstruct their wastewater systems; from drains and sewers to massive storage tanks, and back-end treatment facilities.
Although it is difficult to determine the cost of this effort, a recent American Petroleum Institute (API) study estimated the initial cost of complying with just three of these regulations (Benzene Neshaps, Toxicity Characteristic, and Primary Sludge) at $8 billion. The study estimated the initial cost of complying with clean fuel requirements at $4 billion, and air toxics standards, many of which will be directed at emissions from wastewater, at $3 billion.
Design and construction of new or modified wastewater systems can easily cost $20-30 million at a small refinery, and well over $100 million at larger facilities.
As high as these costs may be, they do not begin to rival the cost of complying with other less understood water-related regulations such as revised effluent standards for refineries and Maximum Achievable Control Technology (MACT) standards, as well as the regulations that will come out of the reauthorization of Resource Conservation and Recovery Act (RCRA) and the Clean Water Act.
To meet these new regulatory standards, the refinery wastewater system of the mid-90s may require:
- Totally enclosed, emission controlled, hard-piped collection systems and treatment units for all process wastewater.
- Replacement of most surface impoundments, including those used for stormwater, with tanks. (Those impoundments that do remain in service will usually require extensive reconstruction to meet double-liner and other standards.)
- Replacement of in-ground biotreatment systems with totally enclosed bioreactors.
- Additional treatment of stormwater to meet new discharge criteria.
- Extensive polishing treatment for organics, metals, and chlorides to meet new water quality standards.
- Extensive remediation of existing treatment units and sediments in outfall areas.
- Recycling of process water.
Many of these upgrades to wastewater systems will have to be done in the next 5 years, within the same time period as Clean Air Act modifications. As with many environmental rules, those affecting wastewater are complex and difficult to understand.
Dealt with one at a time, and by different groups at a facility, there is a danger that current projects will not meet future requirements, forcing them to be redone at substantial additional cost. Proper understanding of current and future regulatory requirements and development of an integrated master plan can minimize total costs, control cash flow, and ensure continued compliance.
This three-part series presents an overview of the regulatory issues most likely to have a major impact on refinery wastewater systems. Part 1 covers air regulations. Part 2 will look at hazardous waste rules, and Part 3 will go over water regulations.
The discussions include the authors' best judgment on future regulatory requirements. The effects on wastewater system design are presented for each regulation, with the final section of Part 3 providing a summary of how these requirements impact overall system design.
VOC EMISSIONS
There are a number of air regulations that directly affect wastewater treatment, including the final rule for control of Volatile Organic Compounds (VOC) emissions from refinery wastewater management systems.
This rule was published on Nov. 23, 1988 (53 FR 478618) as 40 CFR 60.690.699 (Subpart QQQ). It applies to any construction, modification, or reconstruction of the wastewater system started after May 4, 1987 (the date it was proposed).
These few pages have created much confusion, and even now the specific provisions are not well understood. This confusion is growing, with time, because of numerous other rules relating to VOC controls. The purpose of Subpart QQQ is to reduce the potential for VOC emissions from atmospheric sewer systems resulting from construction of new drain systems or reconstruction and modification of existing systems. It can cover systems from the source to the oil/water separator used in the sewer train.
Most affected facilities have integrated sewer upgrade designs into their projects that incorporated "P" traps, junction box liquid seals of incoming laterals, vapor control for openings (manholes), and many other relatively direct intervention vapor collection/absorption devices.
The proposed controls did not always seem very practical, nor were they easy to maintain. The systems also did not provide adequate control for extremely hazardous substances (EHS), if present.
The rules implied that an adequate control level would be 500 ppm of detectable VOCs, but the suggested efficiency of 95% recovery for control devices is not always adequate for control of EHS chemicals listed in the Clean Air Act Amendments of 1990.
In addition, it is not necessarily always adequate for protection of workers under U.S. Occupational Safety & Health Administration (OSHA) permissible exposure limits (without protection devices).
Compliance with Subpart QQQ became more complicated in 1990 with promulgation of Benzene National Emission Standards for Hazardous Air Pollutants (Neshaps) and Toxicity Characteristic (TC) rules. These rules imposed a different and often conflicting set of controls on streams that had 10 ppm, or 0.5 ppm benzene.
Therefore, before the QQQ rules were implemented to any great degree, U.S. Environmental Protection Agency (EPA) essentially preempted them with benzene controls.
AFFECTED FACILITIES
Standards for control apply to individual drain systems, down to and including the first downstream junction box or oil/water separator. They also can be required for the entire downstream sewer system, down to and including the secondary oil/water separator (the "aggregate facility").
The extent standards apply depends on whether the construction, reconstruction, or modification will result in additional emissions, as well as whether a capital expenditure is involved. Standards generally apply to:
- New individual drain systems that serve new or existing units, regardless of the level of additional emissions; and the aggregate facility, if there will be an emissions increase, regardless of the capital cost.
- Existing individual drain systems, if physical or operational changes will result in an emissions increase; and the aggregate facility, if a capital expenditure (7% of total capital cost of the facility) is involved.
If the total emissions can be offset elsewhere within the existing wastewater treatment facility, the aggregate facility may be exempted from meeting the standard.
EXCLUSIONS
The 1988 rules excluded:
- Wastewater components downstream of the oil/water separator (excluding the slop system)
- Modifications or reconstruction of systems having a catch basin, prior to May 4, 1987
- Air flotation systems, including dissolved air flotation (DAF) and induced air flotation (IAF)
- Totally segregated Stormwater systems
- Stormwater surge tanks.
SPECIFIC EQUIPMENT RULES
The specific equipment for which standards apply are:
- Drain openings
- Junction box covers
- Oil/water separators
- VOC control devices
- Slop oil facilities
- Sewer lines
- Connections or openings.
SPECIAL EQUIPMENT PROVISIONS
Subpart QQQ also provides special rules governing the method of control for certain equipment. These rules are as follows:
- Oil/water separators:
- New
- fixed roof for < 250 gpm (no vent control required)
- closed vent system for 250 gpm (control device required).
- Existing
- fixed roof for < 600 gpm
- fixed roof and control device for 600 gpm, or
- a floating roof (double seal) over the entire separator tank.
- New
- Slop oil tanks are not covered under Subparts K, Ka, or Kb of 40 CFR 60.
- Storage tanks must have fixed roofs.
- Closed (no opening) systems are valid substitutes for sealed systems.
MONITORING
There are provisions for initial and semiannual monitoring with a portable hydrocarbon analyzer using EPA test method 21 to determine if the equipment is performing properly.
BENZENE NESHAPS
The Benzene Neshaps rule was finalized on Mar. 7, 1990 (55 FR 8292), and is described in 40 CFR 61.340-358 (Subpart FF).
This rule primarily impacts facilities with more than 10 megagrams (Mg) total annual benzene (TAB) in their wastewater streams.
For these facilities, the rule generally requires that waste streams containing 10 ppm or more benzene (including nonwastewater streams) must:
- Be treated to reduce the concentration of benzene to a level < 10 ppm or by 99% or greater, and
- Be managed prior to treatment in units (sewers, ditches, impoundments, tanks, separators) equipped with specified emission controls.
This is a complex rule with numerous specifications for monitoring, reporting, and control methods. The point of generation at which the TAB is to be measured proved to be a source of much confusion.
For example, the point of generation for desalter water (the major source of benzene in the wastewater) is the exit from the desalter, not any associated deoiling unit. However, for any streams treated for sulfur removal, the point of generation for the TAB calculation is the exit from the sour water stripper.
Organic waste streams must be included in the TAB if mixed with water at some point after its generation. Many refineries that thought they were under the 10 Mg threshold discovered they are covered by the rule.
The original compliance date for facilities to control and treat affected streams was Mar. 7, 1992. Because of confusion surrounding interpretation of this rule and the probability of widespread noncompliance and several lawsuits, EPA has staved the effectiveness of Subpart FF and will repromulgate it no later than Dec. 1, 1992 (57 FR 8012, Mar. 5, 1992).
Along with the stay, EPA issued clarifying amendments in a Notice of Proposed Rulemaking (57 FR 8017, Mar. 5, 1992), without altering the basic intent and control requirements of the original rule. After repromulgation, facilities will have 90 days to comply with all provisions (approximately Mar. 1, 1993).
EPA is also proposing to grant facility-specific waivers of compliance for a maximum period of up to 2 years, provided there has been a "good faith effort" to meet the compliance date, and that there is an enforceable commitment to obtain "mitigating environmental benefits." EPA has not yet issued guidance on how this will be determined, but it may require offsetting decreases in benzene emissions from other areas of the facility.
The most complete approach to complying with Benzene Neshaps seems to be isolating 10 ppm or greater waste streams, managing them in totally enclosed emission-controlled systems, and treating them in a centralized unit, usually a stripper. After treatment, the streams are combined with the other wastewater streams for treatment in the facility wastewater treatment plant (Fig. 1)
Some facilities may decide to treat individual streams at the source, or group several nearby sources for treatment, using several treatment units throughout the facility. Treated streams could be discharged to the existing sewer system and commingled with untreated wastewater.
This approach may be appropriate for facilities with few affected streams, or where sources are located far apart and the cost of constructing and operating multiple treatment units is less than the cost of enclosed sewers and a central treatment unit (Fig. 2).
With both of these approaches, it may be possible to exempt some streams that have more than 10 ppm benzene. If the amount of benzene in both treated and untreated process wastewater is reduced to below 1 Mg/year, then untreated process wastewater streams are exempt from control and treatment requirements. This exclusion is not allowed for wastes other than process wastewater.
A different approach is to combine all process water streams, regardless of benzene content. Although dilution is not allowed solely for the purpose of achieving compliance by reducing the benzene concentration to allowable levels (i.e., < 10 ppm), additional requirements are provided in the rule for facilities that wish to combine waste streams and use their existing treatment units.
In this case, emission controls must be applied to all wastewater units (sewers, tanks, separators, etc.) until:
- The concentration of benzene in the waste system is below 10 ppm, and either
- The total quantity of benzene in all process water for the facility has been reduced to < 1 Mg/year, or
- The waste stream enters an enhanced biodegradation unit (EBU).
These rules enable a facility to design a sewer system that does not try to segregate wastewater based on benzene content. Often, the combined streams will be < 10 ppm benzene, allowing the continued use of existing biological treatment without adding emission controls to the unit.
If the benzene concentration is 10 ppm after combining the streams, the EBU would have to meet Neshaps emission controls. In both cases, the entire wastewater system up to the EBU has to meet Neshaps control standards. Also note that the EBU has to meet specific performance criteria (Fig. 3). Using this particular approach, the sewer replacement and upgrade of system components may cost more, but could be offset by eliminating the construction and operating costs of a stripper or other benzene-specific treatment unit.
In many cases, an existing sewer system can be upgraded at substantially less cost than a new system, especially if a segregated stormwater system is already in place. Variations of this design, including using a stripper to reduce the TAB to < 1 Mg/year, are worth exploring.
Recycling process water to the desalter and using the sour water stripper are also options with merit, particularly because the total amount of process wastewater can be reduced.
Alternate approaches to meeting Neshaps requirements may offer added benefits as well by:
- Providing "additional environmental benefit," which could qualify a facility for a compliance extension
- Meeting MACT requirements that will be required by 1995-1997 anyway (see the following section on MACT standards)
- Reducing emissions and providing a basis for MACT extensions on other units under the early reduction program
- Reducing waste volumes or water flows that have to be reported under Superfund Amendments and Reauthorization Act (SARA), and may be mandated by RCRA reauthorization and revised refinery effluent standards under the National Pollutant Discharge Elimination System (Npdes) program.
MACT REQUIREMENTS
In the Clean Air Act Amendments of 1990, Congress rewrote Section 112, which deals with Neshaps. Prior to the amendments, EPA was to set standards for Hazardous Air Pollutants (HAPs), which provided an ample margin of safety to protect the public.
There was much disagreement over the interpretation, and EPA was unable to develop more than a few Neshaps over the last 13 years. (The Benzene Neshaps discussed in the previous section was one of these.)
Congress' solution was to shift Section 112 from a health basis to a technology basis, followed by a health-based evaluation (so called residual risk) 8 years after promulgation of an applicable standard.
Copyright 1992 Oil & Gas Journal. All Rights Reserved.
