This paper reviews the design and component of two types of RWHS, namely roof harvesting system (RHS) and pond harvesting system (PHS). The performance in terms of quantity and quality of collected rainwater and energy consumption for RWHS with different capacities were evaluated, as well as the benefits and challenges particularly in environmental, economic and social aspects. Presently, RHS is more commonly applied but its effectiveness is limited by its small scale. The PHS is of larger scale and has greater potentials and effectiveness as an alternative water supply system. Results also indicate the many advantages of PHS especially in terms of economics, environmental aspects and volume of water harvested. While RHS may be suited to individual or existing buildings, PHS has greater potentials and should be applied in newly developed urban areas with wet equatorial climate.

Water reuse for irrigation is increasingly recognized as an essential and economical strategy in areas with water scarcity. A simple, low-cost, low-maintenance, and highly efficient Pond-In-Pond (PIP) treatment system can be used for wastewater reuse. PIP is a treatment technology in which two types of ponds -- anaerobic and aerobic -- are combined into a single pond and consist of a deeper inner section entirely submerged within the outer pond. Previous studies on PIPs and PIP-like systems have reinforced the potential for reuse through promising performance results with BOD removal over 80% and a reduction in land area requirements by approximately 40%. Yet, no prior efforts have been made to understand the performance mechanism of such systems. This study makes use of two, 2-D modeling tools in developing a fundamental understanding of PIP flow dynamics and the expected performance. The modeling results showed that the PIP configuration offers improved flow diversion along with reduced flow velocity. Additionally, the PIP retained approximately 17% more (p<0.05) particles than the traditional pond with most of the particles concentrated within the inner pond. Lower velocity and the higher solids retention in the PIP thus allowed for better treatment performance compared to traditional ponds. The findings from this study can be used as preliminary data for future in-depth investigations of the PIP system leading toward effective and optimal designs. This will help address the major societal concern of water scarcity with low-cost and effective wastewater treatment.

The majority of the phosphogypsum produced by a fertilizer plant in the Philippines is just stockpiled, which is considered a liability with no commercial prospects. It is important that we find use of this industrial waste by-product sooner than it becomes an environmental issue. Our study investigated the economic potential of the phosphogypsum by determining its rare earth elements (REE) composition. Phosphogypsum samples were collected from 2 m-depth trenches at 0.5 m intervals in 24 locations in the tailings ponds. ICPMS analysis of the phosphogypsum samples shows that the ponds have a mean Ʃ REE + Y concentrations of 266.15 mg kg^-1. The individual REE concentrations are within the world average concentrations in phosphogypsum, although there is relative depletion of Yb, Tb, and Tm. There are huge variations in REE concentrations between the ponds, likely because these are produced from the processing of more than ten types of exported phosphate rocks since the start of operation of the fertilizer plant in 1980s. The major REE abundance is in the order of Y (26 %) > Ce (25 %) > La (16 %) > Nd (15 %). There is an estimated 66 M USD worth of REE oxides in the phosphogypsum ponds with a potential added value of 3.3 to 6.6 M USD for 1 to 2 Mt phosphogypsum produced annually at 50 % recovery rate. This study provides a comprehensive REE concentration and economic analyses of Philippine phosphogypsum produced from different types of imported phosphate rocks for potential REE extraction.

Infected fish have been known to recover from mild illness when they are able to locate to warmer water. This study aimed to replicate this ‘behavioural fever’ effect in an aquaculture setting by artificially heating a section of a fish pond (thereby introducing a thermal gradient) and effectively modifying pond design. This was achieved through the construction of a ‘greenhouse’ type structure above a section of the pond. Over the length of the production cycle at three typical Nile tilapia (Oreochromis niloticus) farms, the study collected data on water quality and fish growth and at the end of the cycle, blood samples were taken and total production was recorded. At each farm, fish were divided into two identical ponds, one with a greenhouse covering 3% of the pond surface area and one without. Results showed that greenhouse was effective in warming the surface of the water immediately below it. Oxygen levels were also higher under the greenhouse than outside of it and higher than in the control pond. Fish reared in the greenhouse ponds tended to be larger than the control ponds and had improved physiological and immune status (i.e., better liver and kidney function, higher antioxidant activity and lysozyme count; p &lt; 0.05). The results of this study suggest that low-cost interventions that introduce thermal gradients in aquaculture systems may hold promise for improving health and welfare status of farmed fish in developing countries.

Legacy mining industry has left a large number of tailings ponds exposed to water and wind erosion that causes serious environmental and health problems. Prior to rehabilitation actions a deep sampling of the materials infilling the pond used to be necessary. Thus, the primary objective of this study is to demonstrate the usefulness of the Electrical Resistivity Tomography (ERT) method as a non-invasive tool to determine the physicochemical composition of mine tailings ponds, enabling more efficient and low-cost surveys. To achieve this objective, three ERT profiles and three boreholes in each profile were carried out, from each borehole three waste samples from differents depths were collected and a geochemical characterization of the samples was carried. In order to estimate the composition of the infilling wastes in tailing ponds from electrical resistivity measures, several regression models were calculated for different physicochemical properties and metal concentrations. As a result, a high resistivity area was depicted in profiles G2 and G3 while a non-resistive area (profile G1) was also found. Relationships among low resistivity values and high salinity, clay content and high metal concentrations and mobility were established. Specifically, calibrated models were obtained for electrical conductivity, particles sizes of 0.02-50 µm and 50-2000 µm, total Zn and Cd concentration, and bioavailable Ni, Cd and Fe. Therefore, the ERT technique could be considered as a useful tool for mine tailings ponds characterization, and it can be used to estmate some physicochemical properties and metal concentrations of this mine waste.

Salinity acts as a critical environmental filter on microbial communities in natural systems, negatively affecting microbial diversity. However, how salinity affects the community assembly remains unclear. This study used Wendeng multi-pond saltern as a model to evaluate the prokaryotic community composition and diversity and quantify the relative importance of ecological processes across salinity gradients. Results showed that low saline salterns (45-80 g/L) exhibited higher bacterial diversity than those in high saline salterns (175-265 g/L). The relative abundance of taxa assigned to Halanaerobiaceae, Haloferacaceae, Desulfohalobiaceae, Phormidiaceae, Rohodobacteraceae, and Nitrococcaceae was higher with increasing salinity. Salinity and pH were the primary environmental factors that directly or indirectly determined the composition and diversity of prokaryotic communities. Microbial co-occurrence network dynamics were more complex in the sediment than in water of salterns. An infer Community Assembly Mechanisms by Phylogenetic-bin-based null model analysis (iCAMP) showed that microbial community assembly in sediment and water differed. Our findings provide more information about microbial community structure and the importance of various ecological processes in controlling microbial community diversity and succession along salinity gradients in water and sediment environments.

Buruli ulcer (BU), caused by Mycobacterium ulcerans, is a neglected tropical disease associated with freshwater habitats. A variety of limnic organisms harbor this pathogen, including aquatic bugs (Hemiptera: Heteroptera), which have been hypothesized to be epidemiologically important reservoirs. Aquatic Hemiptera exhibit high levels of diversity in the tropics, but species identification remains challenging. In this study, we collected aquatic bugs from emerging foci of BU in the Southwest Region of Cameroon, which were identified using morphological and molecular methods. The bugs were screened for mycobacterial DNA and a selection of 20 mycobacteria-positive specimens from the families Gerridae and Veliidae were subjected to next-generation sequencing. Only one individual revealed putative M. ulcerans DNA, but all specimens contained sequences from the widespread alpha-proteobacterial symbiont, Wolbachia. Phylogenetic analysis placed the Wolbachia sequences into supergroups A, B and F. Circularized mitogenomes were obtained for seven gerrids and two veliids, the first from these families for the African continent. This study suggests that aquatic Hemiptera may have a minor role (if any) in the spread of BU in Southwest Cameroon. Our metagenomic analysis provides new insights into the incursion of Wolbachia into aquatic environments and generates valuable resources to aid molecular taxonomic studies of aquatic Hemiptera.

Fish currently provide 6.7% of all protein consumed by humans globally, nevertheless, aquaculture system has been linked to fish and environmental contamination and disease outbreak. This study aims to isolate, identify, and characterise, bacteria in fish and pond water as well as the antibiotic profile of detected Coliforms. The susceptibility of the isolates was tested using the Kirby-Bauer disc diffusion method on Mueller Hinton agar. A total of forty (40) isolates were isolated from the water samples of which (5) species were Gram Positive bacteria and 35 species of Gram Negative bacteria. The temperature for all ponds ranged from 25°C to 28°C. The mean bacteria count for pond C1 to T2 were 4.9 × 102, 4.9 × 102, 5.4 × 102, 2.5 × 102, 2.2 × 102, and 1.9 × 102 CFU/ml respectively. All isolates were 100% resistant to ceftazidime, cefuroxime and augmentin. More resistance to cefixime (80%) and gentamicin (73.3%) and nitrofurantoin (66.7%) was recorded. However, only 16.6% and 8.3% of the isolates were resistant to ciprofloxacin and ofloxacin respectively. The multiple antimicrobial resistance index (MARI) ranged from 0.5 to 0.9. The water quality parameters (temperature and pH) and the type of bacteria detected in all pond type did not differ significantly. The Multi-drug resistance bacteria detected could be pathogenic to fish and consumers.

Increasing salt intake has substantial negative impacts on health and well-being. This review article focusses on the effect of salinity intrusion (SI) on the water quality and community health of coastal Bangladesh and to find out the effectiveness of interventions for reducing the negative effects of salinity. Saline water is a noteworthy reason for hypertension or high blood pressure in the coastal areas. Health status of women especially the pregnant women are vulnerable because of drinking water sodium (DWS) prompting to pre-eclampsia, high blood pressure and hypertension as well as infant mortality. Several interventions such as rainwater harvesting and Pond sand filter (PSF) system as well as managed aquifer recharge (MAR) usage and the integration of mixed sources were reviewed on the content of drinking water sodium (DWS). Although rainwater has the positive impact of low or no sodium intake on human health, it still possesses negative impacts from not having vital minerals. Despite what might be expected, in MAR a steady increment in sodium concentration through the span of the dry season was observed. It is, subsequently, important to increase awareness about drinking water sodium (DWS) intake by providing and adopting correct technological interventions.

Coastal areas are increasingly being damaged with the expansion of seawater intrusion areas. We suggest a three-step method for reducing seawater intrusion areas by predicting future damage to groundwater being used continuously. First, the area most vulnerable to seawater intrusion damage is selected from among 25 areas on the west coast of the Republic of Korea. Having identified the Taean area as the region in question in the second step, we use RCP 4.5 and 8.5 as future sea level rise scenarios and predict the future usage of groundwater using linear-regression analysis of data for the past 10 years. Consequently, for RCP 8.5 (groundwater-usage scenario 1.0), 68.5% of the total Taean area is projected to be influenced by seawater intrusion. In the third step, the effectiveness of seawater intrusion reduction measures is analyzed considering the projected future situation and the local characteristics of the Taean area. After considering the effects of alternative locations, as well as seawater intrusion related data, alternatives were prioritized using a multi-criteria decision-making method. Consequently, 3, 5, and 4 were prioritized in the listed order, and we judged that by applying seawater intrusion area reduction measures according to this result, we will achieve the biggest effect.