A complex urban ecological investigation in a mid-sized Hungarian city - SITE assessment and monitoring of a liveable urban area, PART 1: Water quality measurement.

Urbanization and related environmental pollution have strong effects on stream systems by inducing short duration high-peak floods, raised levels of nutrients and contaminants, altered channel geomorphology, sediment dynamics, and reduced biotic richness. The main purpose of this current study is to detect stream contamination levels in a mid-sized Hungarian city by comparing the results of two separate years (2011, 2018). Discharge, channel geomorphology, and water quality parameters were measured, and load-based contamination was calculated for the city's main watercourse (Gaja Brook). The pH, CaCO3, texture, and heavy metal contents - Cd, Co, Cu, Ni, Pb, and Zn - were reanalysed in the sediment for both investigated years. For comparison, enrichment factors were used to determine sediment accumulation. As a complex parameter, biological water quality was also determined using BMWP and MMCP protocols in 2018. The results show that conductivity and the nutrient concentrations were higher, but the discharge values were lower in 2011 than in 2018. The nitrate load doubled both times in the brook between the first and the last sampling sites. The enrichment factors decreased or stagnated when the values of the two years were compared, but severe enrichment of Cd was detected in the middle of the city and south of the city. The aquatic macroinvertebrate fauna structure defined clean, but slightly impacted watercourses north and south of the city as well, but the abundance and presence of sensitive taxa differed at the sampling sites. Székesfehérvár has better than expected water quality, which can be attributed to the good ecological states of the hydromorphology and the streamside zone.

Design-support and performance estimation using HYDRUS/CW2D: a horizontal flow constructed wetland for polishing SBR effluent.

The 4,000 PE (700 m(3)/d) wastewater treatment plant at Balf, Hungary was based on sequencing batch reactor technology with phosphorus precipitation as the tertiary step. Its effluent met quality thresholds on average, with above-threshold peaks mainly in winter. The HYDRUS/CW2D model package (PC Progress s.r.o.) was used to simulate the treatment performance of a horizontal flow constructed wetland for polishing effluent. The goal of this study was to provide design-supportive information about the suitability of the proposed wetland and to prove the applicability of the computational tool used to gain that information. The simulations showed that the wetland with the proposed layout could not tackle peaks in NH4-N. Other effluent thresholds could be met, including chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen, total inorganic nitrogen and total phosphorus. The tool was unable to simulate COD and BOD5 removal in periods when the electron acceptors were depleted because anaerobic processes are not modelled. Using a tool of such complexity for designing carries excessive work demands and involves many uncertainties. The simulation study highlighted that the model used could still facilitate the design of an effective system by showing the weaknesses of a test scenario as it was demonstrated.

3D printed receptacle with diffuser membrane for manipulating pressurized air and water.

Water research is one of many fields where fused filament fabrication 3D printing offers the freedom of customization and the inclusion of commercial components. We present our 330 mL 3D printed laboratory receptacle that has been customized to control pressurized air and liquid in one body. During our tests, water has been stored without loss, and batches were frozen whilst circulating and diffusing air through the liquid. The printing has been optimized with the slicer software and gcode editing, letting the fused filament 3D printer to build a diffuser membrane surrounded by air-tight walls. Detailed construction instructions are given, including piping and control board for operation. According to the functionality of the receptacle and the aeration system, the solutions have been found durable and low-cost. Disadvantages are the time invested in creating customized code, and certain limitations of the membrane itself.

Influence of lowland forests on subsurface salt accumulation in shallow groundwater areas.

In flat sedimentary plains in areas with a sub-humid climate, tree planting on grasslands and arable lands creates strong hydrological shifts. As a result of deep rooting and high water uptake of trees, groundwater levels drop and subsurface salt accumulation increases. Tree planting has expanded globally and in Hungary it reached rates of 15 000 ha year(-1), being focused mainly in the Great Hungarian Plain where forests replace grasslands and crops in a region with widespread shallow groundwater. We performed soil and groundwater observations in 31 pairs of forest and control plots in the region, including gradients of initial water table depth and salinity, soil layering, and tree species and age. Accumulated tree biomass was positively correlated with soil salinization rates following tree planting, being also affected by species (poplar > common oak > black locust) and stand age. Differences among tree species effects appeared to be related to their growth rates. Due to downward deep percolation and salt leaching episodes during the Hungarian winters, the observed salt accumulation rates were lower than those described under similar settings in the warmer Argentine Pampas.