Resuscitation of Bacteria after Dechlorination of Treated Drinking Water

In this study, the effects of initial bacterial load (102 , 104 and 106 cells/ml) and dechlorination idiosyncrasy on the efficacy of varying concentrations (0.018–0.126% v/v applied for 30 minutes) of a point-of-use chlorine-based proprietary disinfectant (WaterCare®) were investigated in drinking water. Results indicated that higher initial cell populations significantly affected the efficacy of the disinfectant.Subsequent dechlorination of the disinfected water resulted in resuscitation of bacteria. This was demonstrated after 1440 minutes post-dechlorination for Salmonella typhi and after at least 120 minutes for Escherichia coli, Proteus vulgaris and Shigella dysenteriae, particularly at lower disinfectant concentrations (0.018–0.054% v/v). Thus, whilst the use of WaterCare® at the recommended dosage(0.072% v/v or 10 ml to 25 litres of clean water for 30 minutes) may produce microbiologically safe drinking water high initial microbial load and post-disinfection residual chlorine loss may limit its efficacy. Keywords: Bacterial resuscitation, Escherichia coli, Dechlorination, Drinking water, Salmonella typhi, WaterCare

Fungal Airsporal Contamination of Different Hospital Environments in Lagos, Nigeria

Hospital infections caused by fungi have been frequently reported in hospitalized patients, with a high morbidity and mortality, making it increasingly important to the awareness of air quality. This study is designed to isolate, identify and investigate the occurrence of airborne fungal spores present in various working environments of some selected hospitals within Lagos State, Nigeria. Air samples at six working area (reception, out-patient, male ward, female ward, maternity ward and operating theatre) of the selected hospitals were obtained on triplicate of Sabouraud dextrose agar plates, every week days for six consecutive weeks. Isolated fungi were subsequently identified using both microscopic and macroscopic characteristics. Seven species of fungi belonging to three genera were recovered during this study period; Aspergillus niger, A. flavus, A. fumigatus, A. species, Candida species, Penicillium citrinum and P. species. The most abundant fungus encountered in this study is A. niger with P. species being the least isolated fungus from all the investigated hospitals. Of the six working areas sampled in the eight hospitals, the reception and out-patient areas appeared to record the highest occurrence of encountered fungi while the examined operating theatre rooms had the least fungal airsporal contaminant. It was gathered from this study that despite the daily cleaning of the investigated hospital working environments with different antiseptic and disinfectants, fungal contaminant was observed throughout the sampled period. We thereby conclude that the hospital environments are continuously monitored in order to identify and eliminate the sources of these fungal spores

Modelling and prediction of water current using artificial neural networks: A case study of the commodore channel

Water current modelling and prediction techniques along coastal inlets have attracted growing concern in recent years. This is largely so because water current component continues to be a major contributor to movement of sediments, tracers and pollutants, and to a whole range of offshore applications in engineering, environmental observations, exploration and oceanography. However, most research works are lacking adequate methods for developing precise prediction models along the commodore channel in Lagos State. This research work presents water current prediction using Artificial Neural Networks (ANNs). The Back Propagation (BP) technique with feed forward architecture and optimized training algorithm known as Levenbergq-Marquardt was used to develop a Neural Network Water Current Prediction model-(NNWLM) in a MATLAB programming environment. It was passed through model sensitivity analysis and afterwards tested with data from the Commodore channel (Lagos Lagoon). The result revealed prediction accuracy ranging from 0.012 to 0.045 in terms of Mean Square Error (MSE) and 0.80 to 0.83 in terms of correlation coefficient (R-value). With this high performance, the Neural network developed in this work can be used as a veritable tool for water current prediction along the Commodore channel and in extension a wide variety of coastal engineering and development, covering sediment management program: dredging, sand bypassing, beach-contingency plans, and protection of beaches vulnerable to storm erosion and monitoring and prediction of long-term water current variations in coastal inlets. Keywords: Artificial Neural Network, Commodore Channel, Coastal Inlet, Water Current, Back Propagation

RADIOLOGICAL RISKS OF RADIUM-226 ON GROUNDWATER BASED-DRINKING IN KUBWA AND GOSA AREA OF ABUJA , NORTH CENTRAL NIGERIA

The radiological risks associated with radium-226 in groundwater samples were analyzed using Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The mean annual effective dose from the natural radionuclide of radium-226 (226R) was estimated to be 2.2 x 10‒5 mSv. In the groundwater samples, Lifetime average daily dose (LADD) ranged from 1 x 10‒3 to 2 x 10‒3 μg kg‒1 day‒1. The LADDs and the highest cancer mortality risk was found at Kubwa borehole with a value of 3.1 × 10‒8 and lower value reported at Gosa borehole with a value of 1.8 x 10‒8 . The highest cancer morbidity of 9.7 x 10‒9 was noted at Kubwa whereas lower value of 5.2 x 10‒9 reported at Gosa borehole. The radiological risks of 226Ra in the water samples were found to be low, typically in magnitude of 10−7. With this low level of radiological implications, it may be the chemical toxicity associated with 226Ra as a heavy metal. The values obtained in the study area may not pose radiological hazards to the residents that rely on groundwater. At the same time, measures of groundwater quality protection and monitoring should be enhanced and new supply source which has lower risk must found

Radioactivity And Radiological Impact Assessment In Ota-Dumping Site, Ogun State, Nigeria

Background radiation levels and distributed radionuclides in Ota-dumping site were conducted in different stations to determine the concentrations of natural radionuclides and their possible radiological effects. The external gamma absorbed dose rate and concentration of radionuclides in the area were measured using portable hand-held plastic scintillometer (RS-125 Radiation detector). The activity concentrations vary from 2.47 ± 0.3 to 25.01 ± 1.0 BqK-1, 12.49 ± 0.8 to 105.97 ± 0.6 BqK-1 and 15.65 ± 0.2 to 46.95 ± 0.2 BqK-1 for 238U, 232Th and 40K respectively. The highest activity value of 238U, 232Th and 40K reported in stations 11, 12 and 7 respectively. The absorbed gamma dose rates exposed to people in the area varies from 12.65 ± 2.2 to 44.45 ± 6.6 nGry-1 with the highest value of 44.45 ± 6.6 nGry-1 noted 50 m away from the site at station 12. This could be attributed to the effect of geological features and dose rates from the dumping site tilted towards the Northeast Southwest. The annual effective dose, radium equivalent activity and external hazard index exposed to people in the area are 0.055 mSvy-1, 52.22 ± 0.6 BqK-1 and 0.4 respectively. All the values of radiological risks are within the recommended level by [18], but suggest that the inhabitants residing south western (SW) part of area should adjust if possible 500 m away from the dump-site to avoid long term accumulation which could pose cancer risk

Geochemical Analysis of Domestic Groundwater Sources in a Suburb of Ota, Southwestern Nigeria

Groundwater as one of the most valuable natural resources supports human health, economic development and ecological diversity. The activities of many constituents related to groundwater such as micro-organisms, gases, inorganic and organic materials can lead to contamination of well water, municipal drinking water sources and the environment. Therefore, geochemical analyses of domestic groundwater sources within Iju, Southwestern Nigeria have been conducted to determine the groundwater properties of water samples from available hand-dug wells and boreholes within the area. Fifteen (15) water samples sourced from wells and boreholes within the study area were analyzed for their major trace elements using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in the laboratory and physiochemical characteristics such as pH, total dissolved solids and conductivity were calculated to determine the suitability of such water for agricultural and domestic consumption. The bulk analysis on the water samples revealed that majority of the trace elements when compared with the World Health Organization (WHO) drinking water standards and Acme Laboratory Canada Method Detection Limits (MDL) have values that agree with the recommended limit. These findings show that the present status of groundwater in Iju is good for domestic and agricultural purposes. However, the presence of trace elements such as Lead, Bromide, Copper, Potassium, Manganese, Rubidium and Silicon in fairly high quantities in the groundwater samples which may be as a result of treatment in the water or dissolved salts in the groundwater may constitute major health hazards if not quickly checked. In spite of groundwater studies done in Ota, important information on groundwater resources in Iju is still largely unavailable. Thus, groundwater management can be effectively planned based on these results for the study area

Nosocomial infections and the challenges of control in developing countries.

Nosocomial infection is a recognized public health problem world-wide with a prevalence rate of 3.0-20.7% and an incidence rate of 5-10%. It has become increasingly obvious that infections acquired in the hospital lead to increased morbidity and mortality which has added noticeably to economic burden. However, after about three decades of nosocomial infection surveillance and control world-wide, it still remains an important problem for hospitals today. Studies have shown that most hospitals in developing countries especially Africa, have no effective infection control programme due to lack of awareness of the problem, lack of personnel, poor water supply, erratic electricity supply, ineffective antibiotic policies with emergence of multiply antibiotic resistant microbes, poor laboratory backup, poor funding and non-adherence to safe practices by health workers. It is recommended that the cost of hospital infection control programme should be included in the health budget of the country and fund allocated for the infection control committee for routine control purposes and to bear the cost of outbreaks. There is need for adequate staffing and continuous education of staff on the principles of infection control, especially hand washing which is the single most important effective measure to reduce the risks of cross infection.

Analysis of Geotechnical Parameters from Geophysical Information

In our part of the world where legislations related to site investigations before constructions are not strictly enforced, it may be difficult to carrying out a comprehensive geotechnical investigation to characterize a site because of the expenses and the time involved. Another factor that can discourage a developer is the fact that most of the geotechnical tests procedures utilized during site investigations, to a certain extent, alter the existing environment of the site. This study suggests a quick, non-destructive and non-intrusive method of obtaining key subsoil geotechnical properties necessary for foundation design for proposed engineering facilities. Seismic wave velocities generated from near surface refraction method was used to determine the bulk density of soil, Young’s modulus, bulk modulus, shear modulus and allowable bearing capacity of a competent layer that can bear structural load at the particular study site. Also, regression equations were developed in order to directly obtain the bulk density of soil, Young’s modulus, bulk modulus, shear modulus and allowable bearing capacity from the compressional wave velocities. The results obtained correlated with the results of standard geotechnical investigations carried out

Foundation Settlement Determination: A Simplified Approach

The heterogeneous nature of the subsurface requires the use of factual information to deal with rather than empirical or generalized equations. Therefore, there is need to determine the actual rate of possible settlement in the soil before structures are built on it. This information will help to determining the type of foundation design and the kind of reinforcement that will be necessary in constructions. This paper presents a simplified and a faster approach to determining foundation settlement in the soil using real field data acquired from seismic refraction techniques and cone penetration tests. This approach was also able to determine the depth of settlement of each strata of soil. The rate of settlement for the four profiles was found to vary between 0.019 m and 0.035 m. The results obtained revealed the different depth of possible settlement

Foundation Settlement Detennination: A Simplified Approach

The heterogeneous nature of the subswface requires the use of factual information to deal with rather than empirical or generalized equations. Therefore, there is need to determine the actual rate of possible settlement in the soil before structures are built on it. This information will help to determining the type of formdation design and the kind of reinforcement that will be necessary in constructions. This study presents a simplified and a faster approach to determining formdation settlement in the soil using real field data acquired from seismic refraction techniques and cone penetration tests. This approach was also able to determine the depth of settlement of each strata of soil. The rate of settlement for the four profiles was fmmd to vary between 0.019 and 0.035 m. The results obtained revealed the different depthof possible settlemen