First International Conference on MOLDAVIAN RISKS – FROM ...

<strong>First</strong> <strong>International</strong> <strong>Conference</strong> on MOLDAVIAN RISKS - FROM GLOBAL TO LOCAL SCALE
16-19 May 2012, Bacau, Romania
MULTIVARIATE ANALYSIS OF PHYSICO-CHEMICAL
DATA CHARACTERISTICS OF WASTES WITH POTENTIAL
RADIOACTIVE RISK NEAR BACAU CITY
Sorina Zirnea 1 , Iuliana Lazar 2 , Brice Ulrich Saha Foudjo 2, 3 , Gabriel Lazar 1
1 “Vasile Alecsandri” University of Bacau, Department of Mechanical and Environmental
Engineering
2 “Vasile Alecsandri” University of Bacau, Department of Chemical and Food Engineering
3 University of Yaoundé I, Cameroon , Dep. of Biochemistry
Corresponding author: Sorina Zirnea, sorina.zirnea@ub.ro
Abstract: An important environmental issue for Romania is the industrial wastes and their
reintroduction in business and in all its sectors. The problem of valorization of these wastes
is currently discussed under technical and economic, and in particular ecological aspects.
A specific case of hazardous waste is the radioactive waste. Among the main types of
hazardous waste present in appreciable quantities in our country are those generated by the
chemical industry sector prevailing the waste of soda ash (Alba, Dolj and Valcea County)
and phosphogypsum (Bacau County). Phosphogypsum is a waste by-product of phosphoric
acid (H3PO4), an essential component used in the fertilizer industry is mostly disposed of
without any treatment, usually being disposed in phosphogypsum dumps in close to
phosphoric acid plants or being thrown into water or recycled. Per tonne of phosphoric
acid produced are generated about five tones of phosphogypsum. In 2007, the study of
characterization of phosphogypsum from Platform Sofert S.A. Bacau, made by I.C.I.M.
Bucharest, shows that in terms of chemical composition, the waste is not hazardous
because it contains heavy metals (0.1%) and mineral compounds of phosphorus (0.367 to
0.473%). Thus, in 2007 following physico-chemical parameters of phosphogypsum
samples: humidity, loss on calcinations and silica, phosphorus content, alkali metals
content, alkaline earth and heavy metals after specific mineralization for each metal were
analyzed in accordance to applicable standards. Until now, such analysis was not repeated.
Further investigation was conducted by Regional Agency of Environmental Protection
Bacau (RAEP) and was limited to measuring β radioactivity of phosphogypsum and soil
samples using the CMR beta measuring system with ND-304 scintillation probe. In this
study our aim is to analyze public data from this area in order to be able to make a
descriptive statistics interpretation and perform a cluster analysis to identify potential risks
and correlations. Evaluation of potential characteristics of taken samples was performed
using analytical hierarchy process (AHP) and cluster analysis. The results obtained
revealed a marked reduction of radioactivity in the soil in 2011 but also an increase over
the average radioactivity in the phosphogypsum during the years 2007-2010. From this
preliminary analysis we notice the need to resume a complex analysis at the environment
level in the area of the potential risk of radioactive contamination.
Keywords: phosphogypsum, β radioactivity, descriptive statistics, cluster analysis.
99