Separately collected urine ("yellow water") can be utilized as fertilizer. In order to decrease storage volumes and energy consumption for yellow water transport to fields, enrichment of nutrients in yellow water has to be considered. Laboratory-scale batch freeze concentration of yellow water has been tested in ice-front freezing apparatus: a stirred vessel and a falling film freeze concentrator (coolant temperatures: -6 to -16 degrees C). With progressing enrichment of the liquid concentrate, the frozen ice was increasingly contaminated with yellow water constituents (ammonia, total nitrogen, total phosphorus, TOC, and salts determined as conductivity). The higher the initial salinity of the yellow water and the lower the mechanical agitation of the liquid phase contacting the growing ice front, the more the frozen ice was contaminated. The results indicate, that in ice-front freezing devices multistage processes are necessary, i.e. the melted ice phase has to be purified (and the concentrates must be further enriched) in a second or even in a third stage. Energy consumption of this process is very high. However, technical scale suspension freeze concentration is reasonable in centralized ecological sanitation schemes if the population exceeds 0.5 million and distance of yellow water transportation to fields is more than 80 km.

No abstract

No abstract

A method for determination of 226 Ra and 228 Ra in environmental samples using the α-β coincidence liquid scintillation counting (LSC) has been developed. Radium were preconcentrated from environmental samples by coprecipitation with BaSO 4 , then purified from others radionuclide interferences using the cation column exchange (Bio-Rad AG 50 W-X4 resin with 200 -400 mesh size and H + form) and operating in warm temperature which is between 70˚C -80˚C. Then, the Ba(Ra)SO 4 precipitate was filtered through the Millipore filter paper, dried and weighed to calculate chemical yield. The activity concentration of radium isotopes in mixture of liquid scintillation cocktails were measured using LSC after being stored for over 21 days to allow the growth of the progeny nuclides. The method has been validated with a certified reference material supplied by the International Atomic Energy Agency and reliable results were obtained. The radiochemical yields for radium were 59% -90% and recovery was 97% and 80% for 226 Ra and 228 Ra, respectively. Sixteen seawater and fish flesh samples collected in Kapar coastal water have been analyzed with the developed method. The obtained radium activity concentrations in seawater were in the range of 2.08 ± 0.82 mBq/L to 3.69 ± 1.29 mBq/L for 226 Ra and 6.01 ± 3.05 mBq/L to 17.07 ± 6.62 mBq/L for 228 Ra. Meanwhile, the activity concentrations of 226 Ra and 228 Ra in fish flesh were in the range of 11.82 ± 5. Bq/kg dry wt., respectively.

No abstract