Inga ZINICOVSCAIA 1,2 1 Joint Institute for Nuclear Research, 6 Joliot-Curie Str., , Dubna, Russia, 2 Institute of Chemistry of the Academy of Science of Moldova, 3, Academiei Str.,Chisinau, Moldova «NEUTRON ACTIVATION ANALYSIS FOR WASTEWATER TREATMENT»

 wastewaters  solid wastes  oil-fuel  pesticides 2

Wastewater treatment process 3

 Oxidation  Ion exchange  Precipitation  Sorption 4

Sorbents ExpensiveCheap Specially obtained Activated carbon Metal oxides, etc. Obtained from the environment Waste, rough products Plants Alga Microorganisms 5

6 Biosorption Bacteria MicroalgaFungi Yeast

Object of study Spirulina platensis Spirulina is a filamentous plankton cyanobacteria (gram-negative), or a multicellular helical filamentous alga. To carry out the experiment, algological pure culture of Spirulina platensis CNM-CB-02 strain from the National Collection of Nonpathogenic microorganisms (Institute of Microbiology and Biotechnology, Academy of Sciences of Moldova) was used. 7

IBR-2 and Radioanalytical complex REGATA Short irradiation – 3 min Long irradiation- 4 days

Zinc biosorption

Results C ZnSO4·7H2O : 100mg/L and 1000mg/L Experiment time = 1 hour Samples were obtained in 5, 15, 30 and 60 minutes Zinc content in the S. platensis biomass versus to the time of exposure to zinc sulfate: (a) 100 mg/L; (b) 1000 mg/L 56% removed 30% removed 10

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Notation of the variants Form/ amount of spirulina biomass, mgr Amount of residual water, ml Further additionsContact time I st type of experiment I Filtered/ 50100−30 min II Filtered/ ,68 g NaHCO 3 30 min III Filtered/ SP-1 in macro environment required amount for 100 ml medium [20] 30 min II nd type of experiment IVCulture on the third day in 100 ml medium / 50 mg 100 − 3 days Experimental scheme 12

Experimental variant Content of elements in biomass, mg/ kg Spirulina survival ZnFeKAsW I 2060± ± ±4007.6±0.58.2±2 − II 74900± ± ±5004.2±0.33.6±1 − III 82500± ± ±4004.7±0.34.0±1 − IV 52000± ± ±9002.5±0.23.5±1 + M 50±11356± ±9000.6± ±0.3 Zn, Fe, K, As and W content in spirulina biomass after its interaction with wastewater Results 13

Experimental scheme 14

Results Zinc content in wastewater versus the contact time with the S. platensis biomass Zinc content in the S. plantensis biomass versus the contact time with the wastewater initial concentration - 95mg/l Fe and Sb distribution in the Spirulina platensis biomass 15

Chromium and nickel biosorption

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Nickel content in S. platensis biomass and in the wastewater versus the contact time Chromium content in S. platensis biomass and in the wastewater versus the contact time Results 18 66% removed 90% removed

Fe, Zn, and Ba concentrations in S. platensis biomass as a function of the contact time with the industrial effluents containing nickel. Fe and Ni concentrations in S. platensis biomass as a function of the contact time with the industrial effluents containing chromium 19

Conclusions  Spirulina platensis native biomass is an efficient biosorbent for the removal of zinc, chromium and nickel from wastewater;  Metal ions can be efficiently removed from wastewater when their concentration is less than 100 mg/L;  In addition to zinc, chromium and nickel spirulina native biomass accumulates other metals present in wastewater;  It is recommended to use microbial biomass in the process of removal of metals from wastewater at low metal concentrations, or for wastewater post-treatment. 1919

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