Physical-chemical Water Quality Research Articles

Rainwater treatment system efficiency: Household slow sand filter combined with UVC lamp disinfection

A household system to treat rainwater composed of a Household Slow Sand Filter (HSSF) and a commercial ultraviolet lamp reactor was evaluated. Rainwater was collected in the southeast of Brazil (São Carlos, São Paulo) and inoculated with Escherichia coli to simulate contamination. The system was evaluated for 100 consecutive days under real-scale conditions, aiming to remove microbiological and physical-chemical parameters. Results indicated that HSSF removed 1.10 ± 0.33 log of E. coli even with the schmutzdecke in slow formation due to the low concentration of organic matter concentration and scarcity and low diversity of microorganisms in the rainwater. On the other hand, the UV disinfection (UV dose of 30 mJ/cm2) presented an average removal of 4.60 ± 0.58 log, with 87.5 % of the samples presenting absence of microbiological risk. No significant improvement in physical-chemical water quality after the household treatment was observed due to the high quality of raw rainwater. Therefore, it was recognised that rainwater quality was not substantially improved by the HSSF (i.e., filtration could be dispensed) and only UVC lamp disinfection would be enough to produce drinking water. Recontamination was observed during the tests, as weather events and monitored parameters were capable of highlighting the importance of safe storage practices.

Pinpointing drivers of widespread colonization of Legionella pneumophila in a green building: Roles of water softener system, expansion tank, and reduced occupancy

IntroductionLegionella pneumophila is an opportunistic pathogen that is a key contributor to drinking water-associated disease outbreaks in the United States. Prolonged water stagnation periods in building plumbing systems due to low occupancy, especially during building shutdowns, breaks, and holidays, can lead to water quality deterioration and (re)colonization of buildings with L. pneumophila. Water monitoring in buildings typically relies on grab samples with small datasets.MethodsIn this study, a larger dataset was created by sampling a Leadership in Energy and Environmental Design (LEED)-certified data-rich commercial building for L. pneumophila and physical-chemical water quality during the COVID-19 pandemic after reduced building occupancy. A proxy for human occupancy rates using WIFI logins was recorded throughout the study period.ResultsL. pneumophila was observed in grab samples taken throughout the building, where concentrations generally increased with greater distances from the building point of entry to locations throughout the building. Factors conducive to microbial growth were identified in the building including fluctuations in water temperatures, lack of chlorine residual, a low water heater setpoint, colonized water-saving fixtures, prolonged stagnation throughout the building; especially in an expansion tank designed to reduce pressure issues during demand fluctuations, and the presence of oversized softener tanks with ion exchange resin that contributed to chlorine residual removal as well as colonization of the resin with L. pneumophila.DiscussionFlushing and thermal disinfection alone did not resolve the problem, and replacement of the expansion tank ultimately resolved the L. pneumophila issue. As ad-hoc approaches are logistically- and time-intensive, more proactive approaches are needed for informing preventative and corrective actions for reducing the risk of exposure to opportunistic pathogens in the building plumbing.

Physical-Chemical Water Quality Study of the Sava River in Serbia Using the Statistical and Factor Analysis

Physical-Chemical Water Quality Study of the Sava River in Serbia Using the Statistical and Factor Analysis

Water Quality Degradation in the Lower Mekong Basin

The Mekong River is one of the world’s largest rivers, unparalleled in terms of its biodiversity and ecosystem services. As in other regions, sufficient water quality is required to support diverse organisms, habitats, and ecosystems, but in the Mekong region, water quality has not been well studied. Based on biological and physical-chemical data collected over the last two decades, we evaluated spatial-temporal water quality of the Lower Mekong Basin (LMB) using biotic and abiotic assessment metrics. We found that during the 2000s, water quality in the LMB was unpolluted, with “very good” metrics for tributary rivers and “good” status for mainstem rivers. However, during the last decade, water quality has been degraded in the LMB, particularly near Vientiane City; the Sekong, Sesan, and Srepok (3S) Rivers; the Tonle Sap Lake system; and the Mekong Delta. Water quality degradation likely corresponds to flow alteration, erosion, sediment trapping, and point and non-point wastewater, which have occurred from rapid hydropower development, deforestation, intensive agriculture, plastic pollution, and urbanization. Regular biomonitoring, physical-chemical water quality assessment, transparent data sharing, and basin-wide water quality standards or management are needed to sustain water quality to support biodiversity and ecosystem function in the LMB.

The impact of floating net cages on the water quality of riam kanan reservoir, south kalimantan

Reservoirs in Indonesia have been widely used as floating net cages, including in the Riam Kanan Reservoir. The use of the reservoir as a floating net cage has affected the quality of water in the reservoir. The purpose of this study was to analyze the physical and chemical quality of water in the Riam Kanan reservoir due to floating net cages cultivation activities. This study used a purposive random sampling method, with the sampling location determined based on the density of floating net cage cultivation with a total of 8 points and a depth of 2 m, 6 m, and 8 m, respectively. The physical value of water was obtained by direct measurement and the chemical value of water is obtained from the measurement results in the laboratory. The data analysis in this research was the descriptive analysis where the data were obtained from the tables and graphs. The results of the research on the physical-chemical quality of water in the Riam Kanan Reservoir show that the physical values of water such as temperature, smell, taste, and color in the waters of the Riam Kanan Reservoir were still within the normal condition. The value of pH has a value of about 7.18-7.76. The value of Dissolved Oxygen (DO) was about 3.76 mg/l-6.14 mg/l. Nitrate value is about 0.002 mg/l-0.4099 mg/l. The nitrite value was about 0.0012 mg/l-0.0034 mg/l. Ammonia content was about 0.1643 mg/l-0.5132 mg/l. The levels of pH, DO, nitrate, and nitrate were a normal category, but the ammonia level was in the dangerous category. The chemical content increased with the depth of the water, due to the influence of the used feed deposited.

Data on the spatial and temporal variability of physical-chemical water quality indicators of the Cunas River, Peru

This article contains analytical data on the spatial and temporal variability of physical-chemical indicators of water quality in the Cunas River, collected in areas of seven localities, during the rainy and dry period from 2014–2016. The physical-chemical parameters determined in situ were carried out with Hanna Instruments' portable equipment (conductivity, dissolved oxygen, total dissolved solids, temperature, pH and turbidity). Water samples were also collected at a depth of 20 cm in two-liter plastic bottles for the analysis of nitrate, phosphorus, BOD 5 and heavy metals. The determination of nitrate and phosphorus was performed with the MD 600/MaxiDirect photometer and BOD 5 by the respirometric method. The determination of heavy metals was performed by atomic absorption spectrometry using a Shimadzu brand AA-6800 atomic absorption spectrophotometer. The development of this data set can serve as a basis for establishing a monitoring program to conserve the aquatic environment and ensure its various water uses.

Bacterial dynamics in drinking water distribution systems and flow cytometry monitoring scheme optimization

Water biostability is desired within drinking water distribution systems (DWDSs) to limit microbiologically-related operational, aesthetic and, eventually, health-related issues. However, variations in microbiological quality can take place both spatially along DWDS pipelines and temporally at single locations due to biofilm detachment, water quality seasonality and other processes. In this study, long- and short-term trends of bacterial concentration and community structure were investigated in a secondary branch of an unchlorinated DWDS for several months using high-frequency flow cytometry (FCM) and traditional laboratory monitoring campaigns. Long-term trends of bacterial concentrations and community structures were likely caused by changes in the water physical-chemical quality (i.e. pH and conductivity). Short-term daily pattern, instead, resulted in significant variations between the bacterial concentrations and community structures at different hours, likely due to biofilm detachment and loose deposits resuspension related to changes in the local water flow. These patterns, however, showed broad variations and did not persist during the entire monitoring campaign presumably due to the stochasticity of local instantaneous demand and seasonal changes in water consumption. During periods without sensible long-term trends, the sampling hours explain a comparable or larger fraction of the bacterial community diversity compared to dates. The variations observed with FCM were poorly or not detected by traditional laboratory analyses, as the correlation between the two were rather weak, highlighting the limited information provided by traditional approaches. On the other hand, FCM data correlated with water pH and conductivity, underlining the relation between physical-chemical and microbiological water quality. Such results suggest that the advanced control of the physical-chemical water quality could minimize the microbiological water quality variations. Moreover, monitoring campaign planning should take into account the sampling time to reduce the noise caused by daily fluctuations and/or assess the overall quality variations. Finally, as monitoring costs are one of the barriers which prevent a more widespread use of FCM, a monitoring scheme optimization strategy was developed. Such strategy employs the data from an initial high-frequency sampling period to select the sampling hours which maximize the observed variations of bacterial concentration and community composition.

Efficiency of pumpkin (Cucurbita pepo), sweet wormwood (Artemisia annua) and amaranth (Amaranthus dubius) in removing nutrients from a smallscale recirculating aquaponic system

In aquaponic systems, plants absorb dissolved nutrients from aquaculture wastewater for their growth. The removal of nutrients allows reuse of water and minimises wastewater discharge to the surrounding environment. This study evaluated the relative nutrient removal efficiencies of three plant species and the performance of Nile tilapia (Oreochromis niloticus) in a small-scale aquaponic system. Three aquaponic systems were assigned as treatments PU (pumpkin), SW (sweet wormwood) and AM (amaranth). Physical-chemical water quality parameters were measured in the fish tanks as well as hydroponic inlets and outlets. Fish sampling was done every 2 weeks for 60 days. Results showed significantly (p < 0.05) lower nutrient concentrations in the hydroponic outlets than the inlets. There was no significant difference in nutrient removal efficiency of the plants (p > 0.05) for all the tested nutrients except for phosphorus. Phosphorus removal was substantially high in PU (75.5 ± 16.8%) than SW (47.36 ± 14.5%) and AM (40.72 ± 13.2%). In addition, the SW system had better (p < 0.05) relative growth rate (0.06 ± 0.00) than that of PU (0.05 ± 0.00) and AM (0.05 ± 0.00). Nitrogen and phosphorus content in plant tissues was significantly high (p < 0.05) in SW and PU plants respectively. Water quality parameters had a significant influence on the growth of fish (p < 0.05). The growth of fish was not different (p > 0.05) in the three treatments. The findings indicate that the tested plants can reduce nutrients in aquaculture discharge water.

Diagnosis of indicators of physical-chemical quality of water in affluents of the Atoyac river

El agua para riego que se utiliza en la region de Texmelucan, Puebla, y zonas colindantes proviene, principalmente, del deshielo de los volcanes y de los pozos profundos, aunque alrededor de 350 productores emplean aguas residuales. Se evaluaron algunos parametros que inciden en la calidad fisico-quimica del agua cuando se utiliza con fines de riego (pH, CE, Ca 2+ , Mg 2+ , K + , PO 4 2- , SO 4 2- , CO 3 2- , HCO 3 - , Na + , B y Cl - ) mediante un muestreo aleatorio realizado en 28 puntos de diversos afluentes del rio Atoyac. Los resultados muestran que la CE oscilo entre 0 y 0.875 dS m -1 ; el 64.28% correspondio a aguas de baja salinidad y bajo contenido de sodio (clase C1S1), el 28.57% a aguas con salinidad media y bajo contenido de sodio (clase C2S1) y el 7.15% a aguas de salinidad alta y bajo contenido de sodio (clase C3S1). En promedio, el Ca (0.98 meq L -1 ) y Mg (1.11 meq L -1 ) estuvieron presentes en mayor concentracion, lo que modifico favorablemente los valores de la relacion de adsorcion de sodio (RAS). Los iones bicarbonato (HCO 3 - ) en el agua presentaron una media de 1.83 meq L -1 . La concentracion de Cl - , HCO 3 - , CO 3 -2 , B y SO 4 -2 no ha afectado a los cultivos establecidos y la concentracion de PO 42- es un aporte significativo a los cultivos. Estos resultados indican que la region de Texmelucan tiene agua apta para el riego desde el punto de vista fisico-quimico; sin considerar el contenido de metales pesados ni el resultado de los analisis biologicos de la misma.

Estimation of corrosive and scaling trend in drinking water systems in the city of Azogues, Ecuador

The quality of drinking water flowing in a distribution network can possess corrosive characteristics that may cause the material degradation of pipes and accessories. This problem can result in reduction of the service life of pipes and create a major public health problem. The agreement between the physical-chemical water quality analysis and national standards are not enough to confirm the balance of the water quality in terms of corrosion. In order to predict pipe corrosion in water distribution system networks, the corrosive trend was evaluated using the Langelier (LSI), Ryznar (RSI), and Larson-Skold (LRI) indexes based on measurements of pH, temperature, total dissolved solids, alkalinity, calcium hardness, sulfate and chloride. This study was setup with 180 samples collected in six zones of the distribution network, from July to December of 2017, according to the standard methods for the analysis of drinking water. The results indicate a variation of the LSI from -1.22 to -1.68; RSI from 9.75 to 10.52 and LRI from 0.46 to 0.77. A linear model was fitted for each index to predict the corrosion with the water quality conditions of this study case. Therefore, the drinking water of the city of Azogues, Ecuador has a corrosive tendency from significant to severe. Corrosion indices were calculated to provide useful information on the water's corrosiveness. These results indicate the need to constantly monitor the corrosion rate in the distribution network and conduct a laboratory study to adjust effective parameters such as pH, in order to control corrosion.

Laju Pertumbuhan Kerang Abalon Haliotis squamata Melalui Budidaya IMTA (Integrated Multi Trophic Aquaculture) di Pantai Geger, Nusa Dua, Kabupaten Badung, Provinsi Bali

Abalone is an important non fishery commodity that has high potential value to be developed. Abalone culture still faces some problems, such as, relatively slow growth rate, low survival rate and causing environmental pollution. One of the efforts to tackle the problems, is applying the culture system that is environmental friendly, such as IMTA (Integrated Multitrophic Aquaculture). This research aims to identify the growth rate and survival rate of the abalone (Haliotis squamata) and the suitability of chemical and physical environment parameter supporting the integration culture of abalone and seaweed (Gracilaria sp) on different stocking density at Geger beach, Nusa Dua, Bali. This research was performed in 45 days using a complete randomized design method that consist of three treatments and three repetition. The result showed that the highet growth rate was on treat ment T3 which consisted of abalone (Haliotis squamata) 40 individu and 10 bunches of seaweed (Gracilaria sp) 100 grams weight/each individu (0.76%/day), then It followed by T2 treatment that was integrated with 10 bunches of seaweed 50 grams (0.71%/day). The lowest growth rate observed on treatment T1 (control/monoculture) which consisted of 40 individu abalone (Haliotis squamata) (0.59%/day). The highest survival rate found on treatment T2 (97.5%) and followed by treatment T1 as control (94.5%), while the lowest number was found on treatment T3 (83.3%). Physical chemical water quality parameters showed that It supported the growth of both, abalone (Haliotis squamata) and seaweed (Gracilaria sp.) at Geger Beach, Nusa Dua, Badung Regency, Bali Province.

Analysing the effects of water quality on the occurrence of freshwater macroinvertebrate taxa among tropical river basins from different continents

Macroinvertebrates are globally used in environmental monitoring and assessment. However, due to environmental and biological evolution, local adaptations of species might occur. This can contribute to uncertainties in the extrapolation of familyspecific ecological models developed from one region to another. Thus, we aimed to determine if models can be extrapolated to other regions with similar climatic conditions and if a reliable model can be developed from a pooled dataset (consisting of data from different regions). The occurrence of five families was modelled based on physical-chemical water quality variables with classification trees using the data from three tropical river basins (Chaguana in Ecuador, Gilgel Gibe in Ethiopia and Cau in Vietnam). The relevance of each model was tested on complementary data from both the same and other river basins, to test specificity and universality. Furthermore, models with a pooled dataset were developed and tested. Model reliability was assessed based on chance-corrected agreement (Cohen's kappa, kappa) and percent agreement (correctly classified instances, CCI). Values of higher than 0.4 (kappa) and 70% (CCI) were used to classify models as good. Only the pollution sensitive taxon (Leptophlebiidae) resulted in reliable models for most cases. In general, responses of macroinvertebrates towards pollution were different among countries except for the pollution sensitive taxa. Thus, extrapolation of ecological models for sensitive taxa to another river basin with similar climatic and environmental conditions is possible. Nevertheless, this type of systematic analyses for all families is necessary to determine and minimize uncertainty in ecological assessment.

Giardia sp. cysts and Cryptosporidium spp. oocysts dynamics in southeast Brazil: occurrence in surface water and removal in water treatment processes

Raw water and filtered effluent of three drinking water treatment plants (WTP) at a town in Minas Gerais State, southeast Brazil, were monitored over a one-year period for Giardia, Cryptosporidium, microbiological and physical-chemical water quality indicators. High densities of Giardia and Cryptosporidium were detected in two source waters, ranging from 2.0–140 cysts/L and 4.0–510 oocysts/L. Giardia and Cryptosporidium (oo)cyst concentration was not consistently associated with most of the parameters analysed, turbidity being the most promising indicator. It also seems that Giardia and Cryptosporidium concentration was influenced by rainfall. Giardia cysts and Cryptosporidium oocysts were significantly associated in both waters, suggesting a similar pattern of occurrence and common contamination sources. In two of the three water treatment plants analyzed, Giardia and Cryptosporidium were detected in filtered effluents, also in high densities, ranging from 0.066 to 5.5 cysts/L and 0.066 to 13.2 oocysts/L, respectively. Statistical trials to associate protozoa and indicator removal failed in nearly all cases. Nevertheless, the results are interpreted as neither reaffirming nor negating the use of turbidity as a protozoa removal indicator.

Efficiency of the SASS4 rapid bioassessment protocol in determining river health: a case study on the Mhlathuze River, KwaZulu-Natal, South Africa

The purpose of the study was to verify the ability of the South African Scoring System version 4 (SASS4), to assess the health of aquatic ecosystems. The macroinvertebrate community attributes of the Mhlathuze River (KwaZulu-Natal, South Africa) were studied by applying the SASS4 rapid bioassessment method. In testing the effect of spatial and temporal variability in community structure on SASS4 scores it was found that there was a stronger spatial than a temporal effect. It was determined that of the indices used in association with SASS4, the biotic indices (average score per taxon, total score and number of taxa) reflected changes in community structure, but the abiotic habitat quality index did not. It was found that qualitative family-level data provided an adequate classification of sites for use in routine biomonitoring. Ambiguous results were obtained with respect to the importance of measuring abundance during routine biomonitoring. No definite conclusion with respect to the ability of the SASS4 to reflect physical-chemical water quality changes could be drawn from the results obtained in this study. SASS4 was able to reflect the effect of the tidal push from the Mhlathuze Estuary, but this marine influence probably masked less pronounced effects exerted by the remainder of the physical-chemical variables that were investigated. WaterSA Vol.28(1) 2002: 13-22

Optimisation of the monitoring strategy of macroinvertebrate communities in the river Dender, in relation to the EU Water Framework Directive.

The Dender basin in Flanders (Belgium) was used as a case study to implement the European Union (EU) Water Framework Directive. During the last 5 years, ample research on pollution loads and ecological water quality has been done on the Dender River. In addition to biological sampling of macroinvertebrates and fish, automated measurement stations were also used to investigate the spatial-temporal variability of the physical-chemical water quality. This research revealed that the pollution of the Dender River is highly variable. The high nutrient loads result in severe algae blooms during summer, leading to very complex diurnal processes. In this paper, the monitoring strategy for the assessment of the biological water quality in the Dender basin has been reviewed in relation to the EU Water Framework Directive. For this, seasonal macroinvertebrate data were collected and assessed. General trends and hidden structures in these data were analysed by means of classification trees, using different inputs (seasons, river types, and subbasins). Validation of the results was obtained by applying statistical methods. Analysis about the presence and abundance of the macroinvertebrates revealed that there is a distinct difference between the biological water quality in the Dender stem river and its tributaries. There are also seasonal differences between the macroinvertebrate communities when the Dender and its tributaries are examined separately. An optimised monitoring strategy is proposed based on these results and the EU Water Framework Directive. This includes two monitoring campaigns in summer and winter every 3 years. Furthermore, a cyclic monitoring scheme was developed to minimise sampling efforts.

Leaf Decomposition in an Ozark Cave and Spring

ABSTRACT Decomposition of leaves was compared among sites in a stream that originates deep in a cave and then emerges as a spring brook. White oak (Quercus alba) leaf packs and plastic controls were placed in four similar riffle areas: (1) in the cave above a sink hole; (2) in the cave below a sink hole; (3) in the spring under an overhang; and (4) in the spring exposed to direct sunlight (through a forest canopy). Flow, temperature, and other aspects of physical-chemical water quality were constant among sites while availability of natural leaf liter, food abundance and variety, light, and the number and types of invertebrates varied. Processing rates (−k) at the cave sites (1 = 0.0075, 2 = 0.0085) were faster than rates for white oak reported for surface streams, despite a paucity of invertebrates in the cave and similar temperatures. Leaf packs which received sunlight had ten times more invertebrates associated with them than those under the overhang, but similar processing rates (0.019 and 0.024 respectively). Because of these results, we suspect that the decomposition rates outside the cave were faster due to factors other than macroinvertebrates.