Evaluation of solar photosensitised river water treatment in the Caribbean

An economical supply of hygienic potable water is one of the most pressing public health issues facing developing countries in the Caribbean region today. This project investigates the performance of a novel solar photochemical reactor for disinfecting river water. The prototype photochemical reactor was designed, constructed, and tested for the microbiological degradation of faecal coliform present in River Water. The experiments evaluated the efficacy of two photosensitive dyes (malachite green and methylene blue) as agents for detoxification with concentrations ranging from 0.5 to 3.0 mg/L. The photochemical reactor operated in a single-pass mode and compared the disinfection rates with direct photolysis. The photosensitizers showed a high efficacy rate using natural sunlight with microbial reduction ranging from 97 to 99% for concentrations as low as 0.5 mg/L of dye. The sensitizers were found to be photobleaching and were very effective at lower concentrations (<2.0 mg/L). Direct photolysis inactivation rate constants were 0.034 and 0.046 min−1, whilst degradation rates using methylene blue ranged from 0.057 to 0.088 min−1 and for malachite green from 0.057 to 0.086 min−1, respectively. One-way ANOVA was tested between the inflow and outflow pH, as well as the degradation rates constants for both photosensitisers with . Post-solar disinfection included the use of a coconut fiber filter which polished the water removing residual dye concentrations and bacterial contaminants

Modelling of a sustainable refugee camp drainage system for stormwater management

A novel decentralised Sustainable Refugee Camp Drainage System (SRCDS) has been developed for the effective management of stormwater in the Dadaab refugee camp, Kenya. The SRCDS uses the principle of Best Management Practices (BMPs) for runoff generated from extreme rainfall events in order to minimise flooding of inhabited areas of the camp. The performance of the drainage system was modelled by the Storm-water Management Model (SWMM) and Micro Drainage Sustainable Drainage Systems (MDSuDS) software to obtain: (i) the total stormwater flow in a sub-catchment in order to obtain total runoff volume and peak runoff rate and (ii) the required dimensions of the SRCDS to effectively drain and store runoff for reuse. The results showed that the total volume of runoff generated over the sub-catchment area reduces significantly as the volume of water drained by the SRCDS increases, and the peak runoff rate decreases as the size of the SRCDS increases. The SRCDS was effective in dealing with the peak rate and total volume of runoff anticipated

Developing novel photocatalytic cementitious permeable pavements for depollution of contaminants and impurities in urban cities

Photocatalyst such as Titanium Dioxide (TiO2) has been recently introduced as a nanoparticle into cementitious permeable pavements. Combining photocatalytic compounds within concrete permeable pavements can aid with depollution of several contaminants found in urban water streams and air impurities. This paper presents research carried out at the Uni-versity of Greenwich, UK using photocatalytic concrete with varying percentages of TiO2 (0 %, 1% and 5%) to assess the levels depollution which can be achieved.Concrete samples were testing against the degradation of 2, 4-Dichlorophenoxyacetic Acid, a harmful chemical found in herbicides. This advanced oxidation process can aid in the re-duction of urban pollution from an air and water perspective, improving sustainability for urban cities. Self-cleaning benefits of photocatalytic concrete permeable pavements can be used to keep urban infrastructure cleaner and more aesthetically pleasing. Experimental tests were carried out on the characterisation of inorganics through X-Ray diffraction and Fourier Transform Infrared Spectroscopy to ensure that the structures of the concrete samples were not altered by addition of the na-noparticles (photocatalyst). Experimental results were compared to that found in previous literature and confirmed that the addition of 5% TiO2 did not affect the structure of the concrete samples and can be a viable option used in urban infrastruc-ture such as permeable pavements

A Simplified Equation for Calculating the Water Quality Index (WQI), Kalu River, Sri Lanka

The water supply system plays a major role in the community. The water source is carefully selected based on quality, quantity, and reliability. The quality of water at its sources is continuously deteriorating due to various anthropogenic activities and is a major concern to public health as well. The Kalu River is one of the major water resources in Sri Lanka that supplies potable water to the Kalutara district (a highly populated area) and Rathnapura district. But, there has been no significant research or investigation to examine anthropogenic activities in the river. Due to this, it is difficult to find any proper study related to the overall water quality in the Kalu River. Therefore, this study covers a crucial part related to the water quality of the Kalu River. The spatiotemporal variation of river water quality is highly important not only to processing any treatment activities but also to implementing policy decisions. In this context, water quality management is a global concern as countries strive to meet the United Nations Sustainable Development Goal 6, which aims to ensure the availability and sustainable management of water and sanitation for all. Poor water quality can have severe consequences on human health, ecosystems, and economies. Contaminated water sources pose risks of waterborne diseases, reduced agricultural productivity, and ecological imbalances. Hence, assessing and improving water quality is crucial for achieving sustainable development worldwide. Therefore, this paper presents a comprehensive analysis of spatiotemporal analysis of the water quality of the Kalu River using the water quality data of eight locations for 6 years from 2017 to 2023. Nine water quality parameters, including the pH, electrical conductivity, temperature, chemical oxygen demand, biological oxygen demand, total nitrate, total phosphate, total sulfate, total chlorine, and hardness, were used to develop a simple equation to investigate the water quality index (WQI) of the river. Higher WQI values were not recorded near the famous Kalutara Bridge throughout the years, even though the area is highly urbanized and toured due to religious importance. Overall, the water quality of the river can be considered acceptable based on the results of the WQI. The country lockdowns due to COVID-19 might have impacted the results in 2020; this can be clearly seen with the variation of the annual WQI average, as it clearly indicates decreased levels of the WQI in the years 2020 and 2021, and again, the rise of the WQI level in 2022, as this time period corresponds to the lockdown season and relaxation of the lockdown season in the country. Somehow, for most cases in the Kalu River, the WQI level is well below 25, which can be considered acceptable and suitable for human purposes. But, it may need some attention towards the areas to find possible reasons that are not in the range. Nevertheless, the results suggest the importance of continuous water quality monitoring in the Kalu River

Assessment of the physical characteristics and stormwater effluent quality of permeable pavement systems containing recycled materials

This paper evaluates the physical characteristics of two recycled materials and the pollutant removal efficiencies of four 0.2 m2 tanked permeable pavement rigs in the laboratory, that contained either natural aggregates or these recycled materials in the sub-base. The selected recycled materials were Crushed Concrete Aggregates (CCA) and Cement-bounded Expanded Polystyrene beads (C-EPS) whilst the natural aggregates were basalt and quartzite. Natural stormwater runoff was used as influent. Effluent was collected for analysis after 7–10 mins of discharge. Influent and effluent were analysed for pH, Chemical Oxygen Demand (COD), Dissolved Oxygen (DO), Electroconductivity (EC), turbidity, Total Suspended Solids (TSS), Total Dissolved Solids (TDS), Nitrate-Nitrogen (NO3-N), reactive phosphorous (PO43-) and sulphates (SO42-). Both CCA and C-EPS had suitable physical properties for use as sub-base materials in PPS. However, C-EPS is recommended for use in pavements with light to no traffic because of its relatively low compressive strength. In terms of pollutant removal efficiencies, significant differences (p 0.05) were found with respect to TSS, turbidity, COD and NO3-N. Effluent from rigs containing CCA and C-EPS saw significant increases in pH, EC and TDS measurements whilst improvements in DO, TSS, turbidity, COD, PO43- and SO42- were observed. All mean values except pH were, however, within the Maximum Permissible Levels (MPLs) of water pollutants discharged into the environment according to the Trinidad and Tobago Environmental Management Authority (EMA) or the United States Environmental Protection Agency (US EPA). In this regard, the CCA and C-EPS performed satisfactorily as sub-base materials in the permeable pavement rigs. It is noted, however, that further analysis is recommended through leaching tests on the recycled materials

Challenges of poor surface water drainage and wastewater management in refugee camps

Since refugee camps are meant to be temporary and setting them up usually require urgency, little attention has been given to provision of surface water drainage and to a lesser extent wastewater management. As the population of refugees in these camps continues to grow, the effectiveness of drainage infrastructure continues to diminish. In addition, availability of sufficient safe drinking water and wastewater management have become difficult in the refugee camps across the world. The present situation in refugee camps across the world, such as flooding and outbreak of water-related diseases in South Sudan refugee camps, has made the need for sustainable approach to solving the problems to be very urgent. One sustainable way of solving the problems of flooding and outbreak of diseases in refugee camps is to provide effective drainage and wastewater infrastructure that ensures all the wastewater are properly collected, treated and reused for various purposes such as agriculture, drinking, laundry and other relevant uses. This paper therefore presents the current state of drainage and wastewater management in two refugee camps and propose low-cost technologies for stormwater management, wastewater collection, treatment and potential reuse, suitable for these refugee camps

Evaluation of the solar photocatalytic degradation of organochlorine compound trichloroethanoic acid using titanium dioxide and zinc oxide in the Caribbean region

© IWA Publishing 2015. Advanced oxidation processes driven by solar energy can be an efficient method in removing organochlorine compounds from river water especially in tropical environments like the Caribbean region. The feasibility of solar photocatalytic degradation of an organochlorine compound, namely trichloroethanoic acid (TCA), which is commonly used in the Caribbean islands of Trinidad and Tobago, was separately assessed using titanium dioxide and zinc oxide as photocatalysts in suspended solution. Overall the prototype solar photoreactor operated and performed efficiently for the photodegradation of TCA. This study showed that a basic photocatalytic oxidation method for treating water using solar energy as the primary driver gives enhanced decomposition rates of the organochlorine compound when coupled to the additional application of the two separate semiconductor photocatalysts. The results further showed that for varying concentrations of TCA and photocatalysts alike, the organochlorine compound could be completely photocatalytically degraded using short exposure times under the applied influx of solar radiation. This means that this process could be optimised by judicious use of sensors so that dosage rates of the photocatalyst could be altered with variations in influent contamination levels, and the exposure time in the reactor could be altered according to daily variations in solar radiation intensity

Artificial neural network simulation of combined permeable pavement and earth energy systems treating storm water

Artificial intelligence techniques, such as neural networks, are modeling tools that can be applied to analyze urban runoff quality issues. Artificial neural networks are frequently used to model various highly variable and nonlinear physical phenomena in the water and environmental engineering fields. The application of neural networks for analyzing the performance of combined permeable pavement and earth energy systems is timely and novel. This paper presents the application of back-propagation neural networks and the testing of the Levenberg-Marquardt, Quasi-Newton, and Bayesian Regularization algorithms. The neural networks were statistically assessed for their goodness of prediction with respect to the biochemical oxygen demand (BOD), ammonia-nitrogen, nitrate-nitrogen, and ortho-phosphate-phosphorus by numerical computation of the mean absolute error, root-mean-square error, mean absolute relative error, and the coefficient of correlation for the prediction compared with the corresponding measured data. The three neural network models were assessed for their efficiency in accurately simulating the effluent water quality parameters from various experimental pavement systems. The models predicted all key parameters with high correlation coefficients and low minimum statistical errors. The back-propagation and feed-forward neural network models performed optimally as pollutant removal predictors with regard to these two sustainable technologies

Permeable (pervious) pavements and geothermal heat pumps: Addressing sustainable urban stormwater management and renewable energy

Water and energy are the two most fundamental ingredients of modern civilisation and are also the most precious and essential resources around the globe. They are inseparably coupled and with increasing pressures on these resources as the world's populations grow, the concepts of a combined approach can be applied while addressing the economic, climate, water and energy crises. Sustainable development depends on the efficient use of water and energy resources and on the widespread of water recycling, reuse and renewable energy. The use of permeable pavements with integrated geothermal heat pumps (GHP) for the treatment of urban runoff is a novel application and addresses the concept of concurrently reducing the carbon footprint for non-conventional heating and cooling systems whilst treating urban stormwater runoff. At The University of Edinburgh, Institute of Infrastructure and Environment, research is being carried out on GHP (ground source) and permeable pavement systems (PPS) to provide scientific evidence of their workability as a combined system for residential and commercial uses. The research enables decision-makers to assess public health risks, treatment requirements and removal efficiencies, and the potential for urban water runoff recycling as well as alleviation of flood risk