The adverse effects of improper disposal of collected and treated wastewater have become inevitable. In order to achieve the desired environmental standards, in addition to the construction of a wastewater treatment plant, there is also a need to evaluate the continuous performance of treatment systems. In Iran, treated wastewater is mostly used in agriculture. Therefore, the use of wastewater with poor quality characteristics can endanger health. In this study, the efficiency of the neural network model in order to predict the performance of the Parkandabad waste water treatment plant in Mashhad, with a semi-mechanical treatment system, was investigated. The first step in predicting the performance of the treatment plant was identification of factors affecting the Total Biochemical Oxygen Demand (TBOD) parameter which is one of the quality indicators of the effluent. In the next step, the neural network model optimized with a genetic algorithm, and effective features as network inputs were used for the predictions of the performance of the treatment plant. Based on the results obtained from the model, the parameters that affect the prediction of TBOD concentration the most were singled out. They are flow rate, organic matter load, dissolved oxygen concentration, temperature, and some active aerators. Paper will consider replacing the semi-mechanical treatment system with the activated sludge process.

Pool filter backwash accounts for a significant share of wastewater generated in swimming pool facilities. Although rinsing water is taken from the expansion tank, it is necessary to replenish water loss on a regular basis. For example, the daily water consumption of a recreational swimming pool and a hydromassage tub with a total capacity of the water treatment system of 75.9m³/h is 9.88m³/d. The rising costs of water intake, wastewater discharge, and water scarcity necessitates that swimming pools seek solutions that would reduce the facility maintenance costs.

One of the options of limiting wastewater discharge is to recycle backwash. The main problem with this is the high content of suspended solids and elevated concentration of chlorine compounds in the backwash. Therefore, before it is discharged into the environment, it is necessary to conduct pre-treatment, in particular, sedimentation and dechlorination. In addition to compliance with the physicochemical standards, it is also necessary to take into account the ecotoxicological impact of wastewater discharge.

The presented studies have analysed the physicochemical and phytotoxicological parameters of backwash from two swimming pools. Ten independent samples were taken from each pool being tested in order to measure several chosen indicators and conduct bioassays using Lepidium sativum, Sinapis alba, and Lemna minor. The influence of dilution and the matrix of diluted backwash were also analysed. Solutions with 0, 5, 10, 25, 50, 75, and 100% of backwash diluted with deionised water, tap water, or rainwater were prepared and the influence of dilution on the obtained responses from plant indicators was determined. The objective of the study was to identify whether it might be possible to use backwash after pre-treatment for the purpose of irrigation.

As a typical fast-growing plain city with the title of “city of hundreds of lakes”, Wuhan, Hubei Province in China, boasts abundant regulating and storing water space. However, this city has suffered from frequent waterlogging and unbalanced storage due to rapid urbanization. To tackle the issue, this study inspired by the idea of “Nature-Based Solutions” (NBS). Taking the major drainage system of Wuhan as an example, it explored the identification and construction of storage and drainage area as well as the planning strategies in the city scale, based on a sustainable urban stormwater system cycle compatible with artificial deployment and natural stormwater process. The stormwater process is simulated with numerical inverse method. Then the drainage network and the natural force get a balance in the system. The result showed that: 1) With the SCS-CN model and surface equal volume filling method, the spaces storing excess surface runoff were identified under the geography and storm recurrence interval; 2) Combining the data of construction land, actual submergence area, and waterlogging points, the major drainage system with emphasis on the restriction of surface elevation were organized. 3) The “storage and drainage function area of major drainage system” was proposed as a NBS. The hierarchical distribution was adopted for layout optimization of urban land use in Wuhan—include the area of storage and drainage, area of strengthened self-drainage, area of waterlogging reduction, and area of low intensity development. Furthermore, it also offered references to the identification and improvement of waterlogging risk points of public facilities in built area.

The South-to-North Water Diversion (SNWD) Project is the largest inter basin water transfer project in the world. Danjiangkou Reservoir is water source of Middle Route Project of the South-to-North Water Diversion Project. Since the water was opened in December 2014, the problem of water shortage in northern China has been greatly alleviated. However, some studies have shown that the SNWD Project greatly reduces the available water resources in the downstream of the reservoir and affects the vegetation growth and agricultural production in the downstream and upstream. On the other hand, the problems of permanent land occupation, water storage and resettlement caused by the SNWD Project have caused many ecological and environmental problems in the reservoir area, and have a profound impact on the whole basin. It is of great value to evaluate the changes of ecological environment in the basin under the SNWD Project, which is of great value for guiding the ecological construction and development of the basin and scientific water transfer, and also provides a reference for the scientific identification of the basin ecological environment response mechanism under the influence of large-scale water conservancy projects. At present, before and after the Middle Route Project of SNWD Project, the quantitative research on the change characteristics and response law of the overall ecological environment in Danjiangkou reservoir area is lack. Therefore, this study takes Danjiangkou reservoir and Han River Basin as the research object, calculates and analyzes the spatial-temporal dynamic changes of reservoir water volume, watershed vegetation and ecosystem services value before and after water diversion, explores the influence of water volume on the changes of vegetation and ecosystem services value, with the help of land use, climate, socio-economic data to understand the driving forces of vegetation and ecosystem services value change, quantitatively evaluate the impact of SNWD Project on the ecological environment of the river basin, and scientifically identify the ecological environment of the river basin from the two aspects of basic data support and theoretical basis. The response characteristics of the basin ecological environment to the SNWD Project are scientifically identified, which lays the foundation for improving the incentive system of ecological environment protection.

A series of urgent issues such as global warming, frequent natural disasters, and water shortages are largely result from heavy human interference and its induced changes of landscape structure. How the landscape pattern variation impacts the surface runoff remains an unsolved issue for watershed water management. In the past decades, the action of ecological environment protection and projects of returning farmland to forests and grasslands have significantly changed the landscape pattern in Fuhe Basin of Poyang Lake watershed, which will inevitably affect the hydrological cycle of the basin. In this study, the SWAT (Soil and Water Assessment Tool) model for the Fuhe Basin was firstly built to predict the runoff depth for the divided 31 subbasins during three periods from 1990 to 1999, 2000 to 2008 and 2009 to 2013. Meanwhile, dynamic changes of landscape pattern were analyzed Based on the land use and cover data in the year of 1990, 2000, and 2008. Finally, the correlations between different landscape indicators and surface runoff were quantified over subbasins using Spearman Correlation analysis.

Results showed that the SWAT model is applicable in Fuhe Basin with R² (correlation coefficient) and E_ns (Nash-Sutcliffe efficiency coefficient) larger than 0.85 for runoff prediction. Based on the land use and cover data in the year of 1990, 2000, and 2008, the landscape index were calculated. The fragmentation degree increased first and then decreased during the two transition periods. The landscape patches shape became more complicated and connectivity of different landscapes decreased and then increased, among which the forest and paddy field have greatest fragmentation degree. Forest has a larger dominance degree, which was highly connectable to patches of other various types of landscape. According to the changes of landscape pattern from 1990 to 2008, the smaller fragmentation degree, more complex patch shape, and more uneven distribution of landscape patches led to more precipitation interception and runoff reduction.

From the perspective of the landscape type, the landscape area ratio (PLAND) of dry land, paddy field, water area, urban and rural construction land patches has a significantly positive correlation with surface runoff, while PLAND and FRAC_AM (Area Weighted Patch Fractal Dimension) index of forestland have a significantly negative correlation with surface runoff. The complexity of forestland patch shape strengthened the interception of rainfall and plant transpiration of land surface, which would reduce water yield. The expansion of urban impervious area, aggravating landscape fragmentation, reduced runoff interception and increased surface runoff, which can be indicated by positive relation with PLAND and FRAC_AM index of urban construction. Deeply understanding surface runoff alternations, induced by landscape patterns changes, would provide theoretical support for solving the problems of sustainable utilization of water resources, but also offers best management practices (BMPs) for land management.