The reliability and process capability assessment of suspended growth sewage treatment plant in Melaka, Malaysia.

This paper presents the promising method of synchronizing the Six Sigma and reliability analyses at 15 sewage treatment plants (STPs) operating in Melaka, Malaysia. Five different suspended growth treatment technologies in various capacities were investigated. The sequential batch reactor (SBR) and extended aeration activated sludge (EAAS) processes, conventional activated sludge (CAS), aerated lagoon (AL), and oxidation pond (OP) were compared using innovative Niku's treatment reliability and Six Sigma process capability method for biological oxygen demand (BOD5), chemical oxygen demand (COD), total suspended solids (TSS), oil and grease (O&G), and ammoniacal nitrogen (NH3-N) effluent parameters and justified the importance of understanding the lognormal behavior of the effluent parameters in interpreting the performance monitoring results and discharge compliance. The results showed that the SBR and EAAS systems relatively fulfilled the highest performance (>95%) compared to conventional systems to ensure the high quality of effluent discharge. Although the whole system is incapable of removing nutrients efficiently, ranging between 42.31% and 90.48%, may lead to eutrophication issues. Process modification and treatment control should become a critical priority in order to reduce variability, improve stability, and increase the efficiency of nutrient removal. These initiatives promote global sustainable development goals (SDGs) 2030 and the domestic water sector transformation (WST) 2040 by treatment cost reduction, improving environmental sustainability and guaranteeing social and health benefits.

Doses to patients in routine X-ray examinations in Malaysia.

A collaborative national survey initiated by the University of Malaya and the Ministry of Health was conducted from 1993 to 1995 to establish baseline patient dose data for seven common types (12 projections) of X-ray examinations in Malaysia. A total of 12 randomly selected public hospitals and 867 patients were included in this survey. The entrance surface doses (ESD) received by the patients were measured using thermoluminescent dosemeters (TLDs) attached to the patient's skin. Histograms are presented showing wide, positively skewed distributions of measured entrance surface doses for each examination. Mean, median, first and third quartile values of ESD and median effective dose are reported. Survey results are generally comparable with those reported in the UK, USA and by the International Atomic Energy Agency (IAEA). The results also provide information on dose level for a lower weight population (mean weight 60 kg) compared with the international reference dose values based on a 70 kg standard. The findings support the importance of the on-going national quality assurance programme to ensure doses are kept to a level consistent with optimum image quality. The data will also be useful for the formulation of national guidance levels as recommended by the IAEA. Furthermore, this study provides patient dosimetry information on healthcare level II countries.