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NCAB Decisions 2012

03/2012 | 01/2012

Resolutions of the National Coal Ash Board (NCAB) 03/2012

The NCAB decided in its meeting held in March 2012, to continue to advance and promote research and development on the following subject:

  • Environment – Radiation from concrete containing coal ash and its dependence on the source of coal.
The effect of the source of the coal ash on radiation from concrete Radiation tests were carried out in the NRG labs in Holland on concrete samples from Israel containing coal ash from various coal sources, The tests at the NRG were perfumed as a comparative control of the tests carried out simultaneously at the Soreq Nuclear Research Center in Israel to examine the effect of the source of the coal on the level of ionizing radiation from concretes containing coal ash.
 
Brief description of the Work
Human beings are exposed to low levels of ionizing radiation from construction products via two tracks –external exposure to gamma radiation and internal exposure (of the lungs and the respiratory system) to alpha radiation from the disintegration of inhaled radon and its daughters. The internal exposure considered to be more dangerous than the external exposure, and is also more complex to measure. Israeli Standard 5098 – Setting Limits on the Content of Natural Radioactive Elements in Building Products, provides guidance/instructions on the measurement methods to be used and restrictions set on the exposure of residents and members of the public to ionizing radiation via both tracks.

According to studies carried out worldwide and in Israel, the addition of coal ash to concrete significantly reduces the rate of radon exhalation from concrete. This phenomenon has received further confirmation recently in a comprehensive study conducted by a joint team of researchers from the Teknion and the Sore Nuclear Energy Center and the corresponding tests carried out at the NRG laboratories in Holland.

The Coal Ash Board is carrying out a systematic review of the effect of coal ash from different sources, whose characteristics differ from one another, on the exposure to radiation from concrete, and particularly on radon exhalation (decision of the Coal Ash Board of July 2011). At the same time, the Coal Ash Board is examining the findings of the tests carried out using the Israeli method in comparison to the findings of the tests carried out according to the Dutch standard (Coal Ash Board decisions of September 2010, April 2011).
 
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Decisions of the National Coal Ash Board (NCAB) 01/2012

At the meeting of the National Coal Ash Board held in January 2012, it was decided to continue to advance and promote research and development on the following subject:

  • Agriculture – Sewage sludge stabilized with alkaline lime and fly ash additives for agricultural use.
  • Environment – Monitoring of odor emission from sewage stabilized with alkaline lime and fly ash additives.
Sewage sludge stabilized with lime and fly ash additives for agricultural use A follow-up study to monitor and supervise the agricultural application of sewage sludge stabilized with fly ash and lime. Investigator: Dr. Pinchas Fine, Volcani Center, ARO.
 
Brief description of the Work
The use of fly ash as an alkaline component, together with lime, to stabilize sewage sludge for agricultural use as an organic and mineral additive to the soil, is based on the American N-Viro technology developed by a group of researchers and developers in Ohio. It has been applied in numerous facilities throughout the United States and in other countries for the past 30 years. The addition of high pH alkaline substances, such as fly and lime, pasteurizes the sludge and makes it possible to use it without restriction in agriculture (such as for crops intended for human consumption). The addition of fly ash helps to stabilize the sludge (reducing ammonia emission and noxious odors) and turns it from a semi-liquid substance with 20% solids (its composition following compression in the sewage treatment plant) into a solid, friable substance (70% solids), which can be effectively scattered on fields. The current phase of the research is aimed mainly at overseeing the implementation of the application of sewage sludge stabilized with the alkaline additives lime and fly ash, produced at the Dan-Viro facility in the Shafdan Wastewater Treatment Plant, and at performing a follow up on the agricultural and environmental effects of adding the treated sludge to the soil. The study is being carried out in collaboration with Dan-Viro, the owner of the facility at the Shafdan. It constitutes a continuation of the study’s preliminary stage (Coal Ash Board Decision September 2007), carried out during 2008-2011 and in which the environmental aspects of the land application of the treated sludge were investigated in initial field experiments.
 
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Odor emissions from sewage stabilized with alkaline lime and fly ash Assessment of odor nuisance that can be anticipated from sludge stabilized with coal ash and alkaline lime additives. Investigator: Dr. Yael Laor, Dr. Pinchas Fine, Neve Yaar Research Center, ARO.
 
Brief overview
Microbial activity in sludge leads to the creation and accumulation of ammonium, which under certain conditions can turn into ammonia that is volatile and hence emitted into the environment. Addition of lime and coal ash results in a rise in the pH level of the sludge-containing mixtures, leading to two opposing effects: an acceleration of the transition from ammonium to ammonia, and a reduction in the microbial activity.

As a result of irregularities that occurred in the production of the stabilized sewage using alkaline lime and fly ash additives in the Dan-Viro facility at the Shafdan Wastewater Treatment Plant, the Ministry of Environmental Protection decided on a sludge-treatment procedure that requires exceptional enrichment with lime in order to step up the stabilization process. The resulting high level of lime, damages the quality of the sludge from the agricultural point of view. Odor tests that prove that stabilizing sewage sludge using alkaline lime and fly ash additives can reach the required stabilization level by using the original lime content within a 24-hour treatment period, will enable the continued production of a product which is optimal for agricultural use.

Air samples from the sewage sludge stabilized with alkaline lime and fly ash additives will be at the Dan-Viro facility in the Shafdan plant at different points in its production process and after the treated sludge is held in a container for 24 hours. Odor analyses will be carried out in the Neve Yaar specialized laboratory, and the findings fed into a distribution assessment model that considers the local climactic and geographic conditions.
 
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