From: Hunt, Tim

To: Spence, Kelley

Cc: Bradfield, John; Dunkins, Robin; Vipin Varma

Subject: NSPS follow-up

Date: Monday, January 20, 2014 7:21:26 PM

Attachments: TRS treatment at hard-pipe mills_NCASI Summary 1-20-14.pdf

Kelley,

As a follow-up to our November meeting, here is some additional information from  hardpipe mills

showing significant TRS reductions (roughly 70%) that NCASI was able to compile. I hope you find

this helpful.  Please let me know if you have any questions.

Tim Hunt

Senior Director, Air Quality Programs

Tim_Hunt@afandpa.org

(202) 463-2588

AMERICAN FOREST & PAPER ASSOCIATION

1101 K Street, N.W., Suite 700

Washington, D.C. 20005

 

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ncasi – summary of available information – Jan 2014

Treatment of Total Reduced Sulfur (TRS) Compounds in Kraft Mill Condensates at Facilities 

Employing the Clean Condensate Alternative (CCA) Option

Background 

The Maximum Achievable Control Technology (MACT) rule for subpart S sources requires the collection 

and treatment of hazardous air pollutants (HAPs) in kraft pulping condensates by either (a) collecting

and discharging condensates below the surface of a biological treatment system (hardpiping) or (b) 

routing condensates to a steam stripper, to reduce total HAP’s by at least 92 percent or more by weight 

(§63.446). In lieu of the requirement to collect and treat emissions from high volume low concentration 

(HVLC) sources such as the brownstock washers, facilities are allowed to demonstrate compliance using 

the clean condensate alternative (CCA) (§63.447). Majority of facilities utilizing the CCA option 

demonstrate compliance by over-collecting and over-treating HAP in condensates. Emissions reductions 

under CCA are achieved by (a) diverting additional condensates away from open sewers and primary 

clarifier(s) and (b) reducing the HAP content in condensates used in brownstock washer showers and 

other affected process sources. 

In the context of the ongoing review of new source performance standards (NSPS) for kraft pulp mill 

sources, EPA requested a qualitative assessment on the extent of control of total reduced sulfur (TRS)

compounds achieved at facilities that utilize the CCA option. The following apply: 

1. The over-collection of condensates under CCA, for treatment in steam strippers or in biological 

treatment systems, results in a corresponding reduction in HAP and TRS content in process 

water and brownstock washer shower water. The use of cleaner condensates, as process and 

shower water, can lead to lower TRS emissions from brownstock washers, i.e., a certain level of 

control is achieved due to changes in condensate reuse practices. However, the impact of 

condensate quality on TRS emissions has not been the subject of technical studies since the 

MACT rule focused only on HAP emissions.

2. Facilities that treat over-collected condensates in steam strippers achieve TRS control when the 

stripper-off-gases (SOG) are incinerated. TRS control in this case is expected to be similar to that 

achieved from the incineration of LVHC and HVLC gases. (Stripper-off-gases (SOG) are burned 

along with low volume high concentration (LVHC) gases in boilers, lime kilns, or incinerators). 

3. Facilities that over-collect condensates in the hardpipe for subsequent treatment in biological 

treatment systems also achieve TRS control. However, an assessment of the level of TRS control 

achieved at hardpiping mills using CCA requires knowledge of (a) TRS content in pulp mill 

condensates and (b) TRS control across aerated biological treatment systems. Unfortunately, 

given that the subpart S MACT rule focused primarily on HAPs, there is a lack of comprehensive 

information on TRS contents in pulp mill condensates and on its removal across biological 

treatment systems. 

 
ncasi – summary of available information – Jan 2014

Concurrent TRS Control Achieved as a Result of CCA Approaches 

TRS content in hardpiped condensates 

As part of a study to investigate odor around wastewater treatment plants (WWTPs), NCASI evaluated 

existing analytical methods and developed new methods to identify and quantify wastewater 

constituents that may contribute to odors in and around treatment systems. As part of this effort, 

NCASI Method RSC-02.02 - “Reduced Sulfur Compounds by Direct Injection GC/PFPD,” was employed for 

the determination of total (inorganic) sulfide, methyl mercaptan (MeSH), dimethyl sulfide (DMS), 

dimethyl disulfide (DMDS), and dimethyl trisulfide (DMTS) in pulp and paper mill wastewaters (NCASI 

Technical Bulletin No. 933). The appendix to TB No. 933 includes analytical results for wastewater 

streams from a number of facilities, including TRS concentrations in hardpiped condensates at four pulp 

mills. Additionally, NCASI also carried out a detailed study to quantify TRS emissions from WWTPs 

situated at kraft mills in 2005/06. As part of this study, concurrent liquid sampling was carried out to 

quantify the levels of organic reduced sulfur compounds (RSC) using NCASI Method RSC-02.02 (NCASI 

Technical Bulletin No. 956). Two hard-pipe mills were included in this study. 

The combined dataset consists of eleven grab samples at six pulp mills. TRS concentrations in hardpiped 

condensates at these mills ranged from 27 to 230 mg/L as sulfur, with a mean of 134 mg/L as sulfur. 

When converted to a TRS loading rate and indexed to mill production, this corresponds to a TRS load in 

hardpiped condensates ranging from 0.42 to 6.23 lb/ton as sulfur, with an average of 2.53 lb/ton as 

sulfur. 

 

TRS Control across WWTPs 

TRS emissions from two Aerated Stabilization Basins (ASBs) receiving hardpiped condensates were also 

measured as part of the above-mentioned study. When combined with inlet loading and effluent 

discharge rates, an apparent destruction percent can be calculated through a mass-balance. At Mill A

(from NCASI Technical Bulletin No. 956), the average emission rate was 4.88 g/s as sulfur with an 

apparent percent destruction of 63%. At Mill B, the average emission rate was 1.46 g/s as sulfur; with a 

calculated percent destruction was 76%. The mean percent destruction of TRS compounds in ASBs 

receiving hardpiped condensates was 69%. When combined with the mean TRS loading factor above, 

the average treatment of TRS compounds at hard-pipe mills is 1.75 lb/ton as sulfur. 

By comparison, TRS (as sulfur) emissions from BSWs average 0.055 lb/ton (NCASI 2013). In other words, 

this represents the average level of TRS control that could be achieved by installing hoods on NSPS BSWs 

at CCA mills. By comparison, data on TRS content in condensates (and its destruction across biological 

treatment systems) indicate that significantly higher levels of TRS control is achieved in hardpiping mills 

through MACT compliance. Even when assuming only a 10% level of condensate over-collection in the 

hardpipe (at CCA mills), this corresponds to 0.18 lb/ton (as sulfur) of TRS control (1.75 lb/ton x 0.1), 

much higher than the level of treatment achieved through BSW collection. 

 
ncasi – summary of available information – Jan 2014

Summary 

The over-collection of condensates under CCA achieves TRS control due to (a) removal during biological

treatment and (b) additional reduction in TRS emissions from brownstock washers due to the use of 

cleaner condensates. Facilities treating over-collected condensates in steam strippers achieve levels of 

TRS control from the incineration of SOGs (stripper-off-gases (SOG) are burned along with LVHCs and 

HVLCs in boilers, lime kilns, or incinerators). Additionally, limited characterization studies indicate that 

~70% of the TRS (as sulfur) in condensates is treated when the condensates are collected in a hard pipe 

and subsequently routed to biological treatment. On a lb/ton basis, the level of TRS control achieved 

from treating condensates in biological treatment systems far exceeds the treatment that could be 

achieved by enclosing BSW systems. 

Challenges with quantifying TRS content in process condensates 

Site-specific measurements of TRS loadings and demonstrations of treatment at hard-pipe mills are 

challenging, if not infeasible, at this juncture. The associated sampling and analytical techniques are 

complex and difficult to implement. First and foremost, direct measurements of TRS emissions from 

large wastewater treatment sources require research-level resources and methods (such as the spatial 

ambient air sampling technique outlined in NCASI Technical Bulletin No. 957). In principle, an approach 

similar to the one used in Appendix C Form V could be used to estimate TRS emissions from wastewater 

sources (method used for hardpipe quarterly compliance demonstrations). However, this method 

requires accurate speciated TRS concentration data from the various mixing zones of the ASB. The only

suitable measurement method, NCASI Method RSC -02.02 has sample hold-time and analyte stability 

issues that make it more suitable for research-level projects and analyses. The method is not widely 

offered by contract laboratories and is prohibitively expensive when available. 

References 

National Council for Air and Stream Improvement, Inc. (NCASI). 2013. Compilation of air toxics emissions 

data for sources at pulp and paper mills including boilers. NCASI AIR TOXICS EMISSIONS DATABASE. 

National Council for Air and Stream Improvement, Inc. (NCASI). 2008. Emissions of reduced sulfur 

compounds and methane from kraft mill wastewater treatment plants. Technical Bulletin No. 956, 

Research Triangle Park, NC: National Council for Air and Stream Improvement, Inc. 

National Council for Air and Stream Improvement, Inc. (NCASI). 2008. Spatial ambient air sampling and 

analysis methods for quantifying reduced sulfur compound and methane emissions from kraft mill 

wastewater treatment plants. Technical Bulletin No. 957, Research Triangle Park, NC: National Council 

for Air and Stream Improvement, Inc. 

National Council for Air and Stream Improvement, Inc. (NCASI). 2007. Development and application of a 

method for measuring reduced sulfur compounds in pulp and paper mill wastewaters. Technical Bulletin 

No. 933, Research Triangle Park, NC: National Council for Air and Stream Improvement, Inc.