China has paid more attention to increasing urban and rural drinking water security in recent years. Ensuring the security of drinking water in urban and rural areas is the fundamental condition for protecting the basic interests of the public and is also an important aspect of building a moderately, all-sided prosperous society in China. Taking the Shanshan County in Turpan City of Xinjiang Autonomous Region for an example, this study analyzed the countermeasures of ensuring drinking water security.

Firstly, this paper discusses the current quo of drinking water security in Shanshan. In terms of urban drinking water, problems include that: 1) drinking water sources are polluted to varying degrees; 2) water treatment technologies lag behind compared to the social development; 3) high leakage rate of water supply pipe network, and 4) low emergency handling capability. In terms of the rural drinking water, problems exist that small-scale drinking water security projects are on low construction standard, resulting in low water supply guarantee rate, and poor water source protection and water quality supervision.

Secondly, based on the analysis of current problems, the quantity of the water resources guaranteed is put forward. This paper divides Shanshan County into three units as Karuqi area, Ertanggou area and Kekeya area based on urban or rural land use. This paper proposed the optimal distribution of regional water plants and water supply network for the optimal allocation of regional water resources.

Thirdly, for water quality improvement, a corresponding water purification program is developed for raw water quality problems, including centralized and decentralized water quality treatment, as well as an intelligent water flow control process.

At the same time, some management measures such as water source conservation and risk control measures are proposed in order to promote the security of drinking water. This paper also puts forward relevant strategic suggestions for ensuring the security of drinking water in Shanshan County, including enhancing the equipment for the project, modulizing the system of devices, instrumentation of the management system and developing intellegent water management platform. This study has certain reference value for solving the problems of drinking water security in urban and rural areas in the arid regions in northwest China and similar areas around the world.

Options to develop tanning industries could be hindered even in the presence of huge leather industry raw materials due to the requirements of high-tech contaminant removal technologies, especially in developing countries. This study was initiated to investigate the efficiency of freeze desalination for Cr(VI) removal using refrigerators to generate fresh water. Synthetic solutions that represent major ion compositions of drinking water as well as deionized water to which known concentrations of Cr(VI) spiked into it, were added and frozen in a closed freezer unit. The effects of different parameters such as initial concentration, freeze duration, ice nucleation, fraction of ice volume, and influence of co-occurring ions were evaluated in relation to the quality of produced ice. The physicochemical characteristics of the produced meltwater were also evaluated. A high total water recovery of up to 85% was achieved in the experimental evaluation. Cr(VI) removal efficiency of up to 80% from simulated tap and 93 to 97% for deionized water spiked with Cr(VI) were found in this batch partial freezing. Freeze desalination was found to be relatively viable desalination technology in terms of quality of water produced, options on the use of cost effective refrigerants and technologies which could have a pertinent importance to save energy consumption of freezers.

The objective of this study is to assess the filtering capability of porous pavement models and the quality of rainwater and stormwater filtered by such models. Three slabs of porous asphalt mixtures and two systems composed of porous layers that resulted in porous pavement structures were produced. Data were collected in two phases: using rainwater directly from the sky and then using stormwater collected from a street. The models with different layers were assembled in acrylic boxes and rainwater was stored into the boxes in each rainfall event. Parameters such as pH, dissolved oxygen, ammonia, phosphorus, nitrite, aluminium, chromium, copper, zinc and iron were measured. The infiltration capacity of the models varied from 83.4% to 83.7%. For both rainwater and stormwater quality analyses, there was an increase in the concentration of the following parameters: phosphorus, iron, aluminium, zinc, nitrite, chromium, cooper and pH; there was no significant variation in the concentration of dissolved oxygen; and there was a decrease in ammonia in one of the models. However, the concentrations of only phosphorus and aluminium exceeded the limits established by the Brazilian National Environmental Council and National Water Agency for the use of non-potable water. The models were capable of filtering rainwater and stormwater, and reducing the concentration of ammonia. It can be concluded that it is possible to collect stormwater from asphalt porous surfaces and porous pavements. Porous pavements are able to filter out certain pollutants from stormwater and rainwater, and showed to be an alternative to harvest rainwater for non-potable uses and to recharge the water table.

The paper presents the possibility of applying a colloidal solution of nanosilver in a closed circuit of swimming pool water treatment.

The applied nanosilver solution is characterized as having a very high biocidal effect, with no negative impact on the human and animal body, or the environment.

Because the tested swimming pool is primarily designed for the rehabilitation of disabled people, the water quality must be strictly kept and controlled.

Water quality was analyzed in the following system: prefiltration (mesh filter) - dosing of silver nanoparticle concentrate in the form of an aqueous solution - actual filtration (vacuum filter with multilayer bed) - UV irradiation (low pressure UV lamp) - final disinfection with NaOCl solution.

Samples of pool water for the control of water quality variation in the treatment cycle were taken from 5 points (from pool basin, retention tank, just before filter, just after filter and from water supply system replenishing water lost from swimming pool circuit).

The safety of water for bathing and rehabilitation was appraised by comparing the bacteriological and physicochemical tests results with admissible values specified in hygienic requirements for swimming pools (WHO, 2006: Guidelines for safe recreational water environments. Vol. 2: Swimming pools and similar environments, 2006; DIN 19643, 2012: Water treatment for swimming and bathing pools, in German; Polish Ordinance of the Ministry of Health, 2015: Requirements for water at swimming pools, Journal of Laws Item 2016; the Ministry of Health).

The analysis of the microbiological tests results of the pool water shows that nanosilver solution can be successfully applied for precoating the filter bed and supporting the disinfection system.

Despite finding a large number of mesophilic bacteria in the samples of the filtrate, only 1 CFU/1ml (limit of 100 CFU/1ml) was determined in the samples of the swimming pool water.

Due to the use of the pool, a special attention was paid to the bacteriological purity and the stability of the disinfectant concentration - free chlorine and chloramine concentration as a by-product of pool water disinfection.

As water quality evaluations continue to expand in number of analytes and frequency of measurements, a challenge arises as how to present these data in a manner that can best be used to guide remedial actions and inform water resource decisions. Graphic artists have developed visualization techniques using colors, textures and layers that enhance people’s accessibility to and understanding of data. However, beyond just visual data enhancement, the use of hierarchically arranged spatial patterns or sequentially arranged temporal patterns can provide a means of discerning trends, anomalies and correlations among water quality parameters that would otherwise be difficult to distinguish. A related approach includes comparing actual water quality patterns with either ideal patterns (generated by models) or abstract patterns (created from theories) as a check on their practicality and relevance to the observed datasets. Finally, assessing the connectivity of water quality patterns as a coherent network, rather than as isolated data points, can expose potential feedback loops, counterintuitive or disproportionate effects, and data limitations. Pattern connectivity is also consistent with a systems interpretation of water quality, which may reveal subtle interactions among the water quality components or parameters. Perhaps the greatest advantage of pattern-based approaches is their usefulness to non-scientists (e.g., managers, stakeholders), who often misinterpret or are confused by the language, symbols, mathematics, and graphics appearing in technical reports and journal articles.

The present study investigated the occurrence of selected micropollutants including emerging contaminants (mainly pharmaceuticals and personal care products - PPCPs) in selected swimming pool systems. The study area was selected based on the lack of available information regarding the suspected contamination of swimming pools water by PPCPs. The variety and concentration of chemical compounds in these aquatic systems can be quite diversified, presenting a challenge in terms of both purification and quality control. Determination of PPCPs requires very sensitive analytical methods that make it possible to confirm the presence of tested compounds in a complex organic extract. In this field, GC-MS gas chromatography can be used. This system enables to perform Selected Ion Monitoring, which reduces the detection limits of the investigated analyte.

This paper aims at presentation of analytical methods and strategies adapted to obtain information on the composition and characteristics of water in swimming pool systems with consideration sediments occurred there. There are three types of samples that can be taken from a swimming pool installation: water from pool basin, sediment from the bottom of pool basin and washings from cleaning the filter beds in filtration systems. The individual sample preparation methodology including solid phase extraction was developed for each type of sample.

Wastewater contains a mixture of particles with sizes ranging from 0.001 to more than 1000 microns, which include pathogens, organic and inorganic contaminants. Parasites eggs and cysts present among these particles are removed by sedimentation in Waste Stabilization Ponds (WSP). However, their settling properties are influenced by other wastewater particles which may explain their presence in some effluents even after provision of recommended retention times. Therefore, understanding how wastewater particles behave inside a reactor will enable the understanding of how they influence sedimentation of parasite eggs and how to improve the process. This study assesses and models spatial and seasonal particle size distribution (PSD) dynamics inside a WSP (Buguruni, Tanzania). The 90 m X 183 m X 1.1 m pond was gridded in 30 X 30 m cells and water samples were collected at top and bottom of the cell nodes for dry and rainfall seasons, and the PSD obtained by Malvern mastersizer2000. Results indicate that particles coming into the pond are mainly supracolloidal and settleables with 52.9% and 45.6 % contribution respectively in dry season and 48.9 % and 49.9 % respectively in wet season. Inflow PSD is a unimodal distribution that separates into bimodal PSD of suspended particles and a unimodal PSD of settling particles inside the pond. Stokes equation gives poor estimation of average particle sizes at different locations but results improve when using the modified formula for flocs. Up to 61.5 % and 45.2 % of particles that falls within the size range of helminths eggs (20-80 microns) are found suspended in water during dry and wet seasons respectively, which may account for their presence in some municipal effluents. Studies in spatial characterization of both size and density of primary particles at different location will enable tracing of different pollutants based on their characteristics.

Drought is a continuous process in Thar Desert Pakistan. It is required to assess the extent of this drought for future land use and adaptation. The effect of previous drought was studied on vegetation cover of Thar area, through combined use of drought indices and geographic information (GIS) techniques. Five years (2002, 2005, 2008, 2011 and 2014) were selected to analyze the drought conditions and land use pattern of Thar area. The drought indices used in this study included Normalized Difference Vegetation Index (NDVI) and Standard Precipitation Index (SPI). Images of past drought were compared with post drought images of our targeted area and land use maps were developed for spatio-temporal analysis. Data obtained from satellite images of drought and post drought time periods were analyzed so as to access the changes occurred in land use and vegetation cover through hybrid (digital and visual) interpretation techniques. The results of the study revealed that vegetation in Thar showed an improving trend from 2002 to 2011 and then again began declining from 2011 till 2014. The rainfall occurred at below average rate and SPI values for each year were calculated to be negative, indicating below average rainfall. This actual precipitation data was then compared with the data obtained from TRMM satellite and R² as well as Pearson correlation coefficients were calculated. The R² values for the years 2002 & 2014 were 0.519 and 0.670 respectively. In the same manner, the values of Pearson correlation coefficient for the years 2002 & 2014 were 0.721 & 0.867 respectively. The results showed TRMM satellite’s over-estimation in calculating rainfall data. Further, average temperature for five years under study was analyzed by graphical representation and it was revealed that temperature of Thar has increased by almost 1^oC during the last decade.

The paper compared the removal degrees of selected contaminants of emerging concern in water solutions during advanced oxidation processes such as H₂O₂, O₃, UV and UV/TiO₂. The processes were conducted for 10, 30 and 60 min. The influence of the oxidizing agent dose was also investigated. The tested micropollutants belong to the group of pharmaceuticals (benzocaine, akrydyne, carbamazepine, demecolcine, ibuprofen, diclofenac, caffeine), UV blockers (dioxybenzone), hormones (β-estradiol, 17α-ethinylestradiol, mestranol, progesterone), pesticides (triallat, triclosan, oxadiazon) and food additives (butylated hydroxytoluene). The concentration of those compounds in water matrixes before and after selected oxidation processes was determined by GC-MS analysis preceded by solid phase extraction. The highest removal rate of pharmaceutical compounds was observed during the UV/TiO₂ process. The decomposition of hormones in this process exceeded 96% and the concentration of the UV filter dioxybenzone was reduced by 75%. Single UV irradiation was most effective during the decomposition of butylated hydroxytoluene, triallat and oxadiazon. Toxicological analysis conducted in post-processed water samples indicated the generation of several oxidation by-products with a high toxic potential. The occurrence of tested micropollutant derivatives was confirmed by chromatographic analyses. The identification of the formed compounds was performed based on the obtained mass spectra.

Authors: Olga Ferreira*, João Gomes, Maria J. Calhorda, Elisabete R. Silva*

Over two-thirds of Earth’s surface is covered by water, and its contamination with invasive aquatic organisms (biofouling on submerged surfaces) is an actual challenge. This bioburden, conventionally treated with the release of toxic agents into the surroundings of the contaminated surfaces, is associated with serious environmental and economic penalties, as well as health risks on several industrial applications (e.g. water purification, desalination units).

In this work, it was developed a new non-toxic alternative able to control this biofouling, by applying a novel immobilisation process (WO2016/093719 A1, 2016) for antifouling agents. Briefly, the immobilisation of biocidal agents (e.g. Econea) was performed by providing new functional biocides (e. g. Econea-NCO) capable of being tethered in polymeric coatings.

Bioactivity assessment of the developed antifouling systems suggested that the biocide properties were not significantly affected by the functionalization process. Econea biocide and its functional counterpart showed similar bioactivity against Staphylococcus. aureus, and similar Minimal Inhibitory Concentration (MIC).

Antifouling assessment of coated polymeric substrates with the most promising coatings (silicone marine based paint) containing the immobilized biocide, was carried out at near static conditions in Atlantic seawater (real field test) and in an artificial seawater aquarium. Auspicious antifouling performances were obtained. The coated substrates remained clean after being immersed in those aquatic environments for more than a year.

Furthermore, an ecotoxicity study of biocidal coatings following standards included in the EU hazard assessment of substances and European Eco-label was performed. In accordance with the European standards the coatings were classified as not harmful to the environment.

Structured filters supports (e.g. monoliths) were also successful coated with the best biocidal coatings. Uniform polymeric films were obtained, and adhesion tests are on-going. The next step of this work is to develop an experimental method to confirm the effectiveness of the coated supported filter structures against biofouling at simulated operational conditions (e.g. water circuits). This approach is presented as an alternative non-toxic and long-lasting antifouling strategy.

Acknowledgements

Support for this work was provided by FCT through UID/MULTI/00612/2013 and Pest-OE/QUI/UI0612/2013. O. Ferreira and Dr. E. R. Silva are also grateful for the financial support from FCT, PhD Grant PD/BD/128370/2017 and Post-Doc fellowship SFRH/BPD/88135/2012, respectively. The authors also thank the support of HEMPEL A/S and P. Rijo for the work collaboration.