Persulfate Chemical Oxidation and Sulfates in Groundwater

 

I read with interest a recent article (Peroxygen Talk, June 2010) by FMC's Technical Manager, Phil Block, concerning the fate of sulfate in groundwater when employing FMC's patented Klozur® chemical oxidation process. The article discussed the formation of sulfate and sulfides resulting from the application of persulfate when employing the Klozur® process. Sulfate reducing bacteria can (and do) reduce residual sulfate in the groundwater, the end product from the chemical reaction of persulfate by sulfate reducing bacteria. One concern about the application of persulfate is that sulfate by itself is a pollutant and there are secondary drinking water criteria for sulfates. This is an obvious concern when applying persulfates in drinking water aquifer settings.

Another concern, not addressed in the article, is the formation of sulfuric acid from sulfides which are formed by sulfate reducing bacteria. This occurs commonly in sewers where sulfate reducing bacteria and organic matter are present according to the following reactions:

SO4-- + organic matter ---> S-- + H20 + C02

S-- + 2 H+ ---> H2S

In the presence of oxygen and bacteria in sewers, the bacteria will then oxidize the hydrogen sulfide to sulfuric acid:

H2S + 2O2 ---> H2SO4

The formation of sulfuric acid will cause corrosion of concrete sewers over time. This phenomenon is known as "crown corrosion" as the acid gas rises and attacks the top or "crown" of the pipe. Since sewer systems are often subject infiltration from groundwater, this can be a problem with persulfate oxidation projects. 

Interestingly, a remedy for this is simply to apply hydrogen peroxide for conversion of the acid to elemental sulfur:

H2O2 + H2S ---> 2H2O +S

In conclusion, when utilizing persulfate oxidation processes are employed for groundwater contamination cleanup, the formation of sulfate and hydrogen sulfide should be anticipated and appropriate control measures should be considered as part of the application process to avoid violation of secondary drinking water standards for sulfate and potential creation of crown corrosion problems where sewer systems are present in the treatment area.

Norfolk Ram Group has successfully employed the Klozur® process for numerous groundwater treatment projects.  Call Brian Moran at (508) 478-1276 x12 should you wish to discuss any chemical oxidation project needs you may have.

National Geothermal in today’s New England Real Estate Journal

     An editorial by Mark Bartlett, president of National Geothermal, appears in a special "green building" section in today's New England Real Estate Journal.  The article explains why developers and homeowners should consider geothermal energy as a sustainable alternative to traditional heating and cooling systems.

     Mark also discusses the rapid growth in the New England geothermal industry during the last several years, which has resulted in a 400 percent increase in total geothermal installation projects for National Geothermal.  Click here to read about the environmental and economic benefits of geothermal!

Dispatches from Uganda - Follow up

     I've recently returned from the assessment trip to Shilongo Village, Mbale District in Uganda, which was a fruitful and successful visit. The project is part of the Engineers without Borders program, run through the Tufts University chapter, where I serve as the project mentor.  The travel project team of five students and was highly motivated, resourceful and pragmatic in carrying out the tasks we had defined in the pre-trip planning.

     Upon arrival in the village, we realized that there were multiple sources of water available within the village, and we would need to determine the water quality levels in each source as well as an estimate of how frequently used each source was. The project team strategically utilized each team member's specific skill sets to carry out certain tasks. The students with a more technical background took the lead on the water quality testing and the students with non-technical backgrounds took the lead on the community health surveys. All team members helped each other out and stayed on top of the tasks to make sure we gathered all the information we needed in our limited time in the country. I was very impressed with the students on this trip; their compassion for the people of the village, as well as their willingness to help tempered with the reality of the limitations for the project, showed me that they were a mature, intelligent, inspired collection.  We accomplished a lot in our short time over there, including water quality sampling and testing of the sources (2 boreholes and three springs), as well as limited topographic survey of the areas surrounding the springs. We also held meetings with community leaders and interacted with the general community members. The people in Shilongo were very welcoming and appreciative of our efforts. They will play a crucial role in the long term success of the project, so it was reassuring to see their excitement and commitment to the project.

     As the project moves forward, our background data collections indicates that there will be four (4) potential courses of action for this project, listed in order of importance to the village:

1.  Collection, storage and distribution for the village at the Shilongo Borehole, the main drinking water source in the village

2.  Collection, treatment and storage at the Nabubolo spring or one of the other springs

3.  Rainwater harvesting, and

4.  Development of a brick production process for the village

     The team collected a large amount of useful data during this assessment trip. We will need to pull together all of the GPS, topographic survey, community heath survey  and water quality information in order to put together a design that will aide maximum amount of villagers possible, utilizing sustainable design practices and materials locally available in the Mbale district. The design process will occur over the next year, once Tufts resumes classes and we should have a design ready to be implemented by the second trip, around the same time next year.

Southeastern students to design rain garden

Norfolk Ram's partnership with the students of Southeastern Regional Vocational Technical High School was featured in a recent Stoughton Journal.  We are pleased to provide pro bono support for the school's upcoming sustainability projects, and we applaud the students who have been considering plans to build an on-campus rain garden to purify water run-off that flows into the surrounding habitat.  We are excited to begin work on this project, after which we plan to conduct further meetings with the school's environmental program students to consider other sustainability programs for the Southeastern Regional Vocational Technical High School campus.  For more information about our involvement with SRVTHS, please visit here.

Dispatches from Uganda 2

     I've been in Shilongo for the past couple of days evaluating the water sources and issues that would affect their water quality. Some of the springs are testing positive for bacteria, while the boreholes are testing clean.  The topography is rather undulating, which presents quite a challenge. The students I'm working with are a talented bunch and I've been impressed with their initiative. Hopefully we'll be able to put together a helpful project for the community. ~ John

Dispatches from Uganda

     John McAllister, a project engineer, is currently on a trip to Uganda, working as a mentor for a Tufts University (his alma mater) chapter of the Engineers without Borders program. The project's goal is to provide a safe, clean drinking water supply to the people of the village of Shilongo, an agricultural village of about 1,000 people.  He will provide periodic blog updates of his journey; this is his first entry.

     I arrived in Uganda yesterday after some long travelling.  Scott, one of the project leaders, was there to pick me up at the airport in Entebbe. All together, there are five students from Tufts on the project: Christina, Dave, Drew, Laney, and Scott.  The drive from Entebbe to Mbale was a good six hours, as we got caught in rush hour traffic in the capital, Kampala.  In Mbale, we had lunch with the leader of the NGO we are working with, Foundation for the Development of Needy Communities (FDNC).  They have been very helpful in setting us up and providing us with everything we need.  They set us up in a nice home on the hillside, outside Shilongo, in Nyondo. The house is very nice and even has running water and reliable electricity, which was more than I was expecting! We are about a ten-minute walk away from Shilongo.  The people taking care of the house (David and James) are really nice and they cook delicious food for us.  Last night we played soccer in our front yard with three young kids who live nearby.

     So far the students have completed about 34 community health surveys, which is about the number we were aiming for. The FDNC has provided interns to act as translators (the native language here is Lugisu).

     Today we're going to have one group conducting more interviews and another going around to collect water samples for water quality testing, so I can see where the various sources are. Apparently, during the wet season we are in, there are multiple sources of water for the villagers to draw from.  We hope to set up some meetings with the village leaders and the women this week, and have a whole community meeting this weekend since people are busy during the week with the kids back in school.  So far, so good with the project and hopefully we can put together a successful project to help the people of Shilongo village.

Can Modified Fenton’s Reagent be Used at Sites with Light Non-aqueous Phase Liquid (LNAPL)?

Over the years, we occasionally receive calls where a client asks whether or not modified Fenton's reagent (i.e. hydrogen peroxide and an iron catalyst) can be used at a site where LNAPL is present.  Historically, the application of Fenton's reagent at sites with significant thicknesses of LNAPL has not often been recommended due to potential safety concerns or potential mobilization of NAPL.  Additionally, the application of any oxidant as a sole remedial option at a site containing substantial volumes of NAPL needs to be carefully considered, because the presence of NAPL should be seen as an indication that the mass of oxidant required could be cost prohibitive.  That said, the presence of measurable NAPL should not necessarily preclude the use of Fenton's Reagent as a significant remedial option, in some cases.

Norfolk has had substantial success in using Fenton's Reagent in conjunction with oil recovery mechanisms to enhance the recovery of heating oils and similar petroleum products.  The application of fluid temporarily reduces pore pressures and can "liberate" oil from the soil matrix.  Heat and gasses generated by the Fenton's Reagent can a do the same and also temporarily reduce the viscosity of the oil, thereby creating an opportunity to enhance recovery efforts.  We often find that LNAPL thickness will increase in wells after Fenton's Reagent applications and that oil recovery wells that had previously reached a point of diminishing returns, in terms of oil recovery, will become more productive.  At the same time, treatment of surrounding areas of the site is also accomplished (e.g. an overlying unsaturated soil zone, smear zone, and/or soils and groundwater surrounding the area of NAPL).    

2010 Massachusetts Envirothon

Norfolk's Mark Bartlett joined with over 40 Judges (forming 8 teams of 5+ judges) on May 13, 2010, for the 2010 Massachusetts Envirothon held at the Otter River State Forest in Baldwinville, MA

Over 41 of the state's high schools were represented by teams of students competing for the top prizes.  This year's issue that was addressed by each team of students was "Groundwater Protection".   Click here for more information on this terrific annual event that promotes environmental education and community involvement.

Environmental Business Council of New England's Environ101: Wastewater Series

John McAllister gave a presentation last night (4/29/10) at the Environmental Business Council of New England's Environ101: Wastewater Series,  at Lir Pub on Boylston Street in Boston.  John's presentation gave background on the importance of treating wastewater, the regulations of on-site subsurface disposal systems under Title 5, as well as a brief overview of small package treatments regulated under the DEP's Groundwater Discharge Permit.  The powerpoint slides can be downloaded here, unfortunately though, you won't be able to download the charm provided during the presentation.  If you would like further information on any wastewater and/or permitting issues, feel free to contact John or Kevin Klein at 508-747-7900 extensions 117 and 130, respectively.

Superfund Cleanup Tax Opposed

 

The U.S. Congress has recently proposed reinstatement of the ‘Superfund' tax under the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), which expired in 1995. The original Superfund tax was historically imposed upon industry in order to fund the cleanup of abandoned toxic waste sites in the country. Since its expiration the funding for cleanup has come from general revenues from corporate taxes. Senator Frank Lautenberg (D-NJ) has introduced a bill to reinstate the original tax, which placed a feedstock tax on 42 industrial chemicals and crude oil.  The chemical industry strongly opposes reinstating the tax, however, fearing that it will drive more of an already ailing domestic chemical industry offshore to countries like China who do not impose a tax of this type. The original tax was designed to create a trust fund for cleanup of orphaned sites. The fund grew larger than originally expected and did not run out money until 2003. It is uncertain at this time how fast, if at all, the bill will proceed. If enough support is garnered, however, the bill could pass as a rider to another bill.  A weak Superfund program may lead to undesirable consequences concerning cleanup of toxic and hazardous waste sites.