No abstract

Use of bottled water in Sri Lanka has increased over the last decade, while new brands of bottled water are often introduced to the market. However, the manufacturers' adherence to bottled water regulations is questionable, raising concerns regarding the quality of bottled water. The objective of the current study was to investigate the microbiological and chemical quality of bottled water in Sri Lanka. Thirty bottled water brands were sampled and their chemical and microbiological parameters were analyzed. Microbiological analysis was carried out within 1 to 3, 3 to 6, 6 to 9, and 9 to 12 mo after the date of manufacture. The results indicated that 63% of brands tested exceeded the levels permitted by the Sri Lanka Standards Institution (SLSI) for presumptive total coliforms (TC) (<10 cfu per 100 mL) whereas 97% brands exceeded the World Health Organization (WHO) permitted level. Thirty percent of brands exceeded the limit for presumptive fecal coliforms (FC) (0 cfu per 100 mL in accordance with WHO permitted levels, SLSI and the Sri Lanka Health Ministry requirement). Eighty percent of brands showed higher heterotrophic plate counts (HPC) which exceeded the WHO guidelines for bottled drinking water. Throughout their shelf life, the counts of TC, FC, and HPC bacteria decreased. Bacteria identified were Klebsiella pneumoniae ssp. pneumoniae, Enterobacter cloacae, Pseudomonas aeruginosa, and Pasteurella haemolytica, the most frequently being P. aeruginosa. The dominant fungi identified were Aspergillus sp. and Penicillium sp. Inorganic chemical parameters were within permitted levels for all brands except for initial content of ammonia. The results of this study show the need for the bottling industry to be monitored closely by relevant authorities, in order to provide safe bottled drinking water to consumers in Sri Lanka.

Background Trichomonas vaginalis infection is underreported due to nonspecific clinical presentation and the nonavailability of sensitive laboratory diagnostic tests at the clinical setup. Hence, this study was designed to compare the sensitivity and specificity of microscopy and culture methods with polymerase chain reaction (PCR). The socio-demographic factors associated with the infection were explored. Methods The study was carried out at the National Sexually Transmitted Diseases and Acquired Immuno Deficiency Syndrome Control Programme in Colombo and Sexually Transmitted Diseases and Acquired Immuno Deficiency Syndrome Control Programme in Kandy. Samples were collected from a total of 385 patients including, 272 females (70.7%) and 113 males (29.3%), and tested using microscopy (wet mount and Giemsa staining), culture, and PCR. Genus-specific primer set (TFR1/TFR2) that amplifies 5.8S rRNA and species-specific primer sets (TV16Sf-2/TV16Sr-2 and TVK3/7) that amplifies 18S rRNA and repetitive DNA, respectively, were used. Patient’s socio-demographic and sexual behaviour data were obtained using a standard interviewer-administered questionnaire. Data were analyzed with R statistical software Version 3.6.3. Results The overall prevalence of trichomoniasis was 4.4% (17/385). Of these, six (1.6%) were positive for microscopic examination, 7 (1.8%) were positive for culture, and 13 (3.4%) for TVK3/7, 15 (3.9%) for TV16Sf/r, and TFR1/2 17 (4.4%) were positive for PCR. Sensitivities of PCR using TFR1/2, TV16Sf/r, and TVK3/7 primer sets were 100%, 88.20%, and 76.50%, respectively, against the expanded gold standard. Trichomoniasis was associated with age above 36 (p = 0.033), not using condoms in last three months (p = 0.016), multiple sex partners (p = 0.001), reason for attendance (p = 0.027), symptomatic nature (p = 0.015), and the presence of other sexually transmitted diseases (p = 0.001). Conclusions The study highlighted that age over 36 years, multiple sex partners, not using condoms, reason for attendance, symptomatic nature, and having other sexually transmitted diseases can increase the risk of acquiring trichomoniasis. Furthermore, this study confirmed PCR as highly sensitive and specific diagnostic test for the diagnosis of trichomoniasis in comparison to microscopy and culture methods.

Pseudomonas aeruginosa, a food- and water-borne opportunistic pathogen, constitutes a health risk mostly to immunocompromised patients, and also affects the taste, odour and turbidity of potable water. In order to detect P. aeruginosa in bottled water in Sri Lanka, 36 bottled water brands were collected randomly from retail and supermarkets island wide. P. aeruginosa was detected by the membrane filtration technique, using cetrimide agar supplemented with nalidixic acid. The isolates were subjected to confirmatory tests, viz: ISO 16266:2006 methods and growth at 4 and 42°C, and API 20NE followed by DNA sequencing. Presumptive isolates of P. aeruginosa were observed on cetrimide agar in 50% of brands. Among these isolates, ISO procedures confirmed 58% as P. aeruginosa. Thirty-nine randomly selected isolates were identified as P. aeruginosa by the API 20NE, three of which were further confirmed by DNA sequencing. The presence of P. aeruginosa in bottled water raises health concerns since P. aeruginosa is an indicator of inferior water quality. Therefore, strict regulations and regular monitoring of bottling plants are recommended in order to supply safe and acceptable bottled drinking water to the Sri Lankan market.

Renewable energy is identified as a solution for the growing future electricity demand. Photovoltaic (PV) is a leading type of renewable energy source used for electricity generation. Among the PV systems, distributed PV systems are becoming popular among the domestic consumers and hence the number of domestic PV installations is on the rise continuously. Intermittent output power variations and inability to use the PV power during the night peak hours are major issues with PV systems. Energy storage is a possible mitigation technique for these issues. In order to effectively utilize local generations, storage, and loads, energy management system (EMS) becomes an essential component in future domestic PV installations. EMS for domestic consumers needs to be inexpensive, while a reasonable accuracy level is maintained. In this paper, optimization problem-based EMS and rule-based EMS were developed and compared to investigate the accuracy and the processing speed, thereby to select a fast and accurate EMS for a domestic PV installation. Furthermore, in the proposed EMS, a day-ahead generation and load profiles are generated from predictions, and thus the battery’s state of charge (SoC) levels over a day is estimated through the EMS. In order to utilize the storage effectively, time-varying local maximum and minimum SoC limits for the battery are introduced, which are inside the global maximum and minimum SoC limits. With the aid of real-PV profiles and typical loading profiles, the EMS was implemented using optimization- and rule-based techniques with local SoC limits. The results verified that the rule-based EMS produced accurate results in comparison to optimization-based EMS with lesser processing time. Further results verified that the introduction of local SoC limits improved the performance of the EMS in the unforeseen conditions.