Environmental Technologies

Modified significantly from their original version, the long-awaited federal regulations are considered much more palatable by the U.S. paper industry

Four Years of Work, Debate Produce First Phase of EPA's Cluster Rules

BY BILL NICHOLS

The new Phase I combined air and water "cluster rules" for the pulp and paper industry mark the culmination of nearly four years of discussion by regulatory, environmental, and industrial groups. The cluster rules are the first attempt by the Environmental Protection Agency (EPA) at combining air and water requirements into an ecosystemwide approach to regulate the pulp and paper industry.

The cluster rules were initially proposed in December 1993, with amended proposals for process air emissions in March 1996 and for bleached kraft and sulfite mills in July 1996. This article analyzes the impact the recently signed cluster rule will have on existing North American facilities and particularly mills with bleached and unbleached kraft process.

OVERVIEW. The cluster rules contain technology-based process air and water standards for bleached kraft and soda and paper grade sulfite categories. The rule also contains technology-based process air standards for the other chemical pulp mills (i.e., unbleached kraft and semichemical). The process air rules-i.e., maximum achievable control technology (MACT) III-for mechanical, secondary fiber, nonwood, and paper machines were also issued.

The best available technology (BAT) requirements for bleached paper grade kraft and soda mills are summed up in Table 1. The paper grade sulfite requirements range from totally chlorine-free (TCF) bleaching for nonammonia-based mills to elemental chlorine-free (ECF) bleaching for ammonia and specialty grade mills.

Process air or noncondensible gas (NCG) requirements for bleached and unbleached kraft mills are similar to the original cluster rule proposals (i.e., December 1993 and March 1996). The rule requires treatment of the pulp mill condensates, HVLC gases, and LVHC gases. The semichemical and soda pulping will only require LVHC treatment. The paper grade sulfite mills will require treatment for vents from the digester system, evaporator system, pulp washing, and emission control reduction equipment areas. Additionally, bleach plant gaseous emissions will need to be controlled.

The combustion sources-namely, recovery furnace or liquor incinerator, lime kiln, and smelt-dissolving tank-will require treatment under MACT II. However, only the combustion source portion of the rule was proposed at this time.

The BAT water requirements for the other pulping categories were not proposed at this time and will be submitted according to the following:

Phase II

Unbleached kraft

Semichemical

Mechanical

Nonwood

Secondary fiber nondeink

Secondary fiber deink

Nonintegrated fine

Nonintegrated tissue and board.

Phase III

Dissolving kraft

Dissolving sulfite.

The estimated time for publication of the Phase II and III rules ranges from one year to never. The EPA, in its July 8 Federal Register submittal, indicated it is considering not modifying the water requirements for the other categories. The chemical oxygen demand (COD) standard for the chemical pulping mills will probably be issued, at the earliest, within the next two years.

The original rule included not only ECF but also oxygen or extended delignification requirements. The industry's belief is that ECF is all that is necessary to reduce the bleach plant effluent to both a minimal "toxic chemical" level and an acceptable adsorbable organic halide (AOX) level.

North American usage of ECF bleaching has shown a phenomenal twentyfold increase since 1990. On the other hand, North America represents less than 2%
of the worldwide TCF production. Perhaps these statistics have helped sway the EPA to an ECF position vs a TCF position. The EPA, in its tier approach, recognizes that it will take 11 to 16 years before the U.S. has a significant low-AOX pulp production rate.

After review by the OMB of the proposed rule and its suggested modifications (June through October 1997), the EPA administrator signed it on November 14, 1997. The rule then appeared in the Federal Register in early December; this means that 60 days after its appearance (February 1998), the cluster rules will take effect. The first important date is for the Best Management Practices (BMP) plan that must be submitted within 12 months and implemented within 12 to 36 months of the rule taking effect. Figure 1 provides the timeline for the cluster rules.

The following will discuss the major differences between the currently proposed cluster rules and the original 1993 proposal or assumptions (for the case of the combustion sources) for these major areas:

NCGs

Condensates

Combustion sources

Pulping

Bleaching

End-of-pipe.

The emphasis will be on the kraft process.

NCGs. The following delineates the applicable areas for the kraft pulping MACT I or process air standards:

LVHC system streams

Pulp washing system

Oxygen delignification system

Decker system

- Not use freshwater or whitewater
- Or uses water with hazardous air pollutant (HAP) concentrations greater than or equal to 400 ppm by weight

Knotter system

- Emissions greater than or equal to 0.05 kg/1,000 kg o.d. pulp

Screen system

- Emissions greater than or equal to 0.10 kg/1,000 kg o.d. pulp

Knotter and screen system

- Combined emissions greater than or equal to 0.15 kg/1,000 kg o.d. pulp.

LVHC. There is no difference in the LVHC sources and control requirements under the current proposal. The sources still are the digester, turpentine, evaporator, concentrator, and steam stripper vents. The control requirement is satisfied by any one of the following:

98% total hazardous air pollutant (HAP as methanol) destruction;

1600F and 34-sec. retention time;

20 ppm methanol at 10% oxygen control device exit concentration for a thermal oxidizer.

The major changes are the compliance period (formerly unspecified) of three years from date of rule promulgation and the amount of allowable downtime of 1% for the control equipment. The downtime is exclusive of startups, shutdowns, and malfunctions.

Typically, the LVHC NCGs are incinerated in the lime kiln, meaning that this will need to have a 99% availability when the digesters or evaporator system are running. This uptime requirement may force mills into installing an incinerator to treat the LVHCs and use the lime kiln only as a backup.

HVLC. The control requirements, the same as for the LVHC, have not changed from the original proposal. However, the sources have changed in the following fashion:

Added: intermediate brownstock and interstage oxygen delignification pulp storage chests;

Conditional: deckers if they use wash water containing greater than 400 ppm methanol;

Conditional: knotters, screens, and tanks ahead of brownstock washers if emissions are greater than 0.30 lb methanol/ton of unbleached pulp;

Deleted: existing weak black liquor tanks (still required for new weak black liquor tanks).

The biggest change is the collection exclusion for existing weak black liquor tanks. This is not only a major capital cost savings, but will also reduce the complexity of the HVLC collection system.

The downtime for the HVLC system is a much more generous 4%, exclusive of startups, shutdowns, and malfunctions. This has the potential of not requiring a dedicated backup incineration device. However, again, this is dependent on the uptime of the mill's power or recovery boilers, which are the typical HVLC incineration devices.

Another additional HVLC compliance alternate is the clean condensate alternative (CCA), which includes:

Implement kraft condensate standard control systems

Exclude any reductions that come from equipment installed (prior to December 1993) to comply with local, state, or federal standards

Use treated, reduced HAP condensates in lieu of pulp mill vent controls

Demonstrate compliance

- HAP reduction equal or greater than that achieved by pulp mill vent controls as estimated by emission test data or engineering assessment

- Emission testing

Expanded source to include papermaking and causticizing system

Mill must designate equipment within the expanded sources with which to generate the HAP reduction.

Bleach plant. The sources and control requirements have not changed from the original proposal. They include:

Applicability

- Kraft, sulfite, and soda mills that use chlorinated compounds

Enclose process equipment and route through a closed vent, leak-free system to a control device

Controls (one of the following)

- 99% reduction of chlorinated HAPS

- Outlet concentration of 10 ppmv chlorinated HAP

- Mass emission of 0.001 kg chlorinated HAP/1,000 kg o.d. pulp

Chlorine may be used as a surrogate for measuring total chlorinated HAP

Mechanical, nonwood, and secondary fiber that use elemental chlorine or chlorine dioxide

- EPA not aware of any available control technology, so floor control is "no control."

A scrubber utilizing white liquor and caustic soda is the typical avenue to comply with the requirements. There is also no specified downtime other than for shutdowns, startups, or malfunctions.

MACT III. The MACT III process air standards are also contained in the rule. These will impact:

Mechanical mills

Secondary fiber mills

Nonwood mills

Paper machines.

However, the air standard for these mills is simply a determination that under section 112(d) of the Federal Clean Air Act, no controls for HAPs are warranted at this time. Therefore, the floor control for these sources is "no control."

CONDENSATES. The pulping process wastewater definition has been changed slightly from the original proposal. The digester and turpentine condenser condensates are still included, but NCG system condensates have also been added. In addition, the definition for evaporator condensates has been changed to evaporator system weak liquor feed stage condensates instead of those with a HAP concentration greater than 500 ppm (by weight). This implies collecting the condensates from fifth and sixth effect and the surface condenser at a maximum.

The treatment options and the level of control have also been modified from the original proposal. The treatment options have been expanded from the steam stripper, recycle to controlled system, and biological treatment options to include segregation and treatment of the "rich stream" only.

The recycle to a controlled system would generally refer to using the condensates on deckers and washers equipped with HVLC collection systems. The segregation strategy entails collecting and minimizing the volume of the evaporator, digester, and turpentine condensates. The segregation must collect at least 65% of the HAPs; this normally consists of between 10% and 20% of the total volume of condensates generated in a given effect.

The removal level has also been modified significantly from the original proposal's 90% HAP removal rate to the following:

92% HAP removal

5.1 kg methanol removed/1,000 kg of unbleached pulp for bleached kraft (3.3 kg for unbleached kraft mills)

330 ppmw stripper outlet HAP concentration for bleached kraft mills (220 ppmw for unbleached kraft mills).

Probably the easiest means to accomplish the above is the 5.1 kg/1,000 kg of methanol removal for the bleached kraft mill. This would imply a 4 to 5 kg/1,000 kg BOD removal rate that should be easily attainable with a stripper, where normally a 5 to 10 kg/1,000 kg BOD removal is assumed. Another alternative is to hard pipe the condensates to a well operated biological system capable of 92% HAP reduction as measured by soluble BOD.

However, the one common thread to all the treatment options is a closed-pipe, leak-free collection system. The collection system will need to be inspected every 30 days to ensure
its leak-free integrity. The downtime allowance for the stripper is 10% total, exclusive of shutdowns and startups. The MACT I monitoring, record keeping, and reporting provisions are shown in Table 2.

COMBUSTION SOURCES. The combustion sources, although informally proposed in the past, have never been published in the Federal Register. The combustion sources are the recovery furnace, lime kiln, and smelt-dissolving tank. Figure 2presents the proposed new limits.

The major changes from the initial proposal include:

Smelt-dissolving tank particulate matter for existing sources increased from 0.12 to 0.20 lb/ton of black liquor solids fired

Lime kiln particulate matter for existing sources increased from 0.02 to 0.067 grains per dry standard cubic foot (gr/dscf) corrected to 10% oxygen

Recovery furnace particulate matter for new sources from 0.01 to 0.015 gr/dscf corrected to 8% oxygen

Inclusion of a total particulate matter HAP as an alternate test for the sources

No gaseous organic HAP control

No HCl control.

An alternate "bubble" compliance HAP standard was also suggested. This would recognize those mills whose combustion controls for some devices were doing better than the suggested standard, while other devices were doing more poorly. The bubble alternative involves developing mill-specific particulate matter or particulate matter HAP emission limits based on calculated values of the sum of the individual emission limits for recovery furnaces, smelt-dissolving tanks, and lime kilns. The lack of gaseous organic HAP controls means that direct contact evaporators and black liquor oxidizers do not need to be replaced.

PULPING. The major change in the pulping area is the elimination for bleached kraft mills of the BAT requirement for extended delignification. This elimination is based on increased adsorbable organic halide (AOX) limits described in the bleaching differences section below.

The requirements for the best management practices (BMP) plan have also been modified, and some of the essential points include:

At this time, only required for bleached kraft and paper grade sulfite, although the EPA will more than likely extend them for the other chemical pulping categories

Focus solely on spent pulping liquor, soap, and turpentine discharge control

Return spilled or diverted streams to the maximum extent possible to the pulping and recovery areas or discharge at a rate that will not disrupt the wastewater treatment system

Flexible approach to implementation

Framework for continuously monitoring (i.e., conductivity or pH) the performance and effectiveness of the BMP

Employee training

Exceedance reporting and investigation mechanism

Secondary containment for turpentine bulk storage and, ideally, for spent pulping liquor

Formulate an early warning system to detect trends in spent pulping liquor losses. The parameter of choice is chemical oxygen demand (COD), although conductivity or salt cake losses may be acceptable.

The early warning system entails establishing action limits at the influent to the wastewater treatment facility or at another essential location. There are two limits-the lower, requiring only investigation; and the upper, requiring corrective action. Exceedances of these limits are not intended to constitute a violation of the facility's national pollutant discharge elimination system (NPDES) permit, but failing to monitor or investigate exceedances will result in a violation.

The BMP plan must be submitted within one year of the effective date of the rule. The plan will also include the action limits, which must be based on a six-month monitoring program. The rule compliance schedule (based on the effective date of the rule) consists of:

Within 12 months: implement all BMPs that do not require the construction of containment or diversion system or installation of monitoring/alarm system;

Within 24 months: commence operation of any new or upgraded continuous, automatic monitoring systems not associated with containment or diversion structures;

Within 36 months: complete construction and commence operation of any collection, containment, diversion, or other facilities and their associated continuous monitoring systems;

Within 45 months: establish revised action levels after fully implementing BMPs.

BLEACHING DIFFERENCES. The number of chemicals to be analyzed in the bleach plant effluent and the frequency of monitoring has been modified from the original proposal, including:

Removed acetone, methylene chloride, and methyl ethyl ketone from requirements

Furan limits changed from production-normalized, mass-based limitation to a concentration basis

Monthly analysis for all bleach plant chemicals (i.e., furan, dioxin, and 12 chlorinated phenolic chemicals), except for chloroform, which is weekly

Only daily maximum limits, with exception of chloroform, which will have a monthly average limit.

The BAT technology of ECF, plus the good pulping operation mentioned earlier, also yielded increased AOX limits:

Daily maximum: 0.951 kg/1,000 kg a.d. unbleached pulp

Monthly average: 0.623 kg/1,000 kg a.d. unbleached pulp

Annual average: 0.512 kg/1,000 kg a.d. unbleached pulp for noncontinuous dischargers.

The EPA has also introduced three voluntary advanced technology alternative tiers, shown in Figure 3. The EPA does not believe that TCF is required to meet either Tier II or III. However, they will allow all TCF mills to participate in the voluntary program. The EPA will also allow existing mills that qualify for the tiers to participate. In addition, all or some of a mill's fiberlines may participate in the voluntary program at the same or different levels.

The mills must sign up for the voluntary program within one year of the effective date of the rule. An enforceable compliance schedule is then developed that includes an initial "anti-backsliding" provision to maintain current AOX levels. The mills would then be expected to submit a milestone or interim limitation plan that would be incorporated in the facility's NPDES permit.

The voluntary program also has several incentives, including:

Greater certainty for obtaining extended permit life

Reduced wastewater monitoring (Figure 4)

Lower priority for routine inspections of Tier I (once per two years), Tier II (twice per five years), and Tier III (once per five years)

Public recognition

Reduced penalties by up to 100% for NPDES violations.

Fast-track permit modifications.

END-OF-PIPE. The end-of-pipe changes are significant and include:

Elimination of color requirements on a federal basis

No change from present five-day biochemical oxygen demand and total suspended solids limits

No COD limits promulgated at this time.

The color limits will not be federally mandated for all mills but will be deferred to a water quality standard compliance case only. The COD limits will be eventually promulgated when the EPA has had an opportunity to gather further data and better understand the impact on COD from nonpulping sources (i.e., papermaking, mechanical pulping, etc.).

IMPACT OF RULE. Air. The following are the major opportunities now possible with the new proposal:

With careful consideration, elimination of the initial proposal's backup incineration device for the HVLCs and also, possibly for the LVHCs.

Appropriate condensate control (i.e., to less than 400 ppm HAP) for decker washwater eliminates the need to cover the decker.

Segregation of the evaporator condensates is mandatory whether it is with existing baffles, external heaters, or in a new pre-evaporator. Segregation reduces the size of the stripper and can increase the reuse of condensates by producing an overall lower methanol content combined condensate.

Closed systems may also be employed to handle the condensates.

Lime kiln and smelt-dissolving tank scrubber modifications are probably all that is required to comply with the new particulate matter standards.

BMP. On the other hand, for the water-based requirements, the BMP plan translates into minimizing spent pulping liquor discharges into the sewer system. A BMP plan is ideally designed to remove the COD peaks from the operation, as Figure 5 illustrates.

To determine what peaks must be "shaved," generally a spill potential analysis is performed on the impacted streams. The spill potential is a means of separating in-plant data between base-line or normal operations and spill-related losses from minor and major spills.

Figure 6 represents the spill potential analysis for four mills. Mills A and B are high pollutant loss mills where the losses occur primarily from both baseline and moderate spills. The low major spill contributions indicate the mills are plagued with recurring-probably every other day-spills of an hour to two hours' duration.

On the other hand, mills C and D reflect mills where spills, both moderate and major in nature, are a problem. This means a larger spill control system would be necessary (than for mills A and B) to handle the major spills.

THE FUTURE. The indications are that the cluster rules will be much more palatable than the original proposals. It will probably be two to three years before the EPA issues, if it does, revised end-of-pipe limits for the remaining categories (i.e., unbleached kraft, semichemical, nonintegrated, recycle, etc.). It is anticipated the same degree of relief as was afforded the bleached kraft category. Additionally, within one to three years, the COD limits should be promulgated for the bleached kraft/soda and paper grade sulfite categories.

Finally, based on the proposed cluster rules trends, the future holds the following:

Flow reduction, not only in the pulping area but also in the paper machine area

Raw material maximization, which entails recycling, reusing, and recovering more of the chemicals and fibers used in the pulping and papermaking processes.

Teamwork, where the whole mill is involved in compliance.