Two water treatment plants located in Kandy district, Sri Lanka, which are operating with two different processes, conventional water treatment and Pulsator water treatment followed by rapid sand filtration, were compared from the perspectives of ease and cost of operation. Pulsator technology has an advantage in its compactness, as it incorporates coagulation, flocculation, and clarification in a single unit, while the electricity consumption for the production of a unit of water was 30% higher than for the conventional process. The Pulsator water treatment process was considered to be best suited for populated areas with high land values.
In this work, we prepared calcium phosphate from commercial calcium carbonate and orthophosphoric acid, and from corbicula shells and orthophosphoric acid, by a hydrothermal process. The chemical composition and powder properties of the products were investigated. Commercial calcium carbonate and corbicula shells reacted with orthophosphoric acid to produce calcium hydrogen phosphate via the hydrothermal process. The reaction between commercial calcium carbonate and orthophosphoric acid occurred in 1 h at 120ºC, while the reaction between corbicula shells and orthophosphoric acid needed over 3 h at 120ºC.
In this study, we hydrated calcines of biomineral calcium carbonate resources such as eggshells and scallop shells and converted them to hydroxyapatite (HAp) under different conditions for use as Ru catalyst supports. The catalytic activity of Ru/HAp in the hydrolysis of sodium borohydride was investigated by measuring the volume of hydrogen gas generated from the alkaline solution at 298 K. The results clarify that, when different calcium sources are used as starting materials, high Ru content does not always produce high catalytic activity. The hydrogen generation rate is closely correlated with average pore size of the catalyst. High-performance catalysts obtained in the present study have average pore sizes of 20 nm or less and a molar ratio Ca/P of approximately 1.60.
Cyanobacteria produce potent toxins which have been responsible for numerous livestock and human poisonings. Among cyanotoxins, microcystins, cylindrospermopsins and nodularins are known to cause acute and chronic illnesses. Concern about cyanotoxins in the dry zone water sources of Sri Lanka has grown due to a numerous negative health impacts, including the epidemic of Chronic Kidney Disease of unknown etiology (CKDu). The study aimed a region of high CKDu prevalence in Sri Lanka, Girandurukotte which consisted of CKDu and CKD patients and their well waters. Control samples were collected from other parts and all were analyzed in terms of potential cyanotoxin producers. A questionnaire analysis was carried out with 330 subjects (CKD n=33, CKDu n= 244 patients and healthy individuals n=53). Eleven factors showed significant difference (p<0.05) that could be related to the CKDu. Among them, well water source for drinking was (p=0) notable. Potential microcystin and cylindrospermopsin producing cyanobacteria were morphologically identified from 110 (CKD n=11, CKDu n=74 and Healthy individuals n=25) water samples. Compared to Girandurukotte patients' well water samples, cyanobacterial diversity was found to be less in healthy individuals' well waters. Among potential toxin producers, presence of Phormidium spp in CKDu patients' well waters were found to be significant (P=0.004) compared to other two populations. 50 CKDu and 15 CKD + healthy individuals' well water samples were assayed for partial mycE gene, cylindrospermopsin specific NRPS and PK genes and partial nodularin synthetase (nda) gene. Among these, presence of cylindrospermopsin producers (p= 0.049) and nodularin producing Nodularia species (p=0.0029) were found to be significant.