We studied water loss performance in a model plant, the Tufted sedge (Carex elata All.), which is an active water balance component of subsurface flow constructed wetlands. Due to active regulation of transpiration, the volume and dynamics of water loss in these constructed wetlands are difficult to plan without preliminary and targeted measurements and calculations with regard to the specific plant component. We estimated transpiration values in the laboratory based on daytime transpiration ranges for spring, summer and autumn, and examined the transpiration effect of the hydraulic load. During spring, water loss via transpiration can reach 83% of the hydraulic load on certain days. During summer, this value can increase to 100% of the hydraulic load, which means that the daytime transpiration can significantly affect effluent concentration. Air humidity proved to be the most critical environmental factor for water loss resulting from transpiration, therefore a water discharge plan designed in such a way as to be able to also adjust soil moisture is the key to optimal water circulation at the system level.

This paper offers a novel application of our model worked out in Maple environment to help understand the very complex transport processes in horizontal subsurface flow constructed wetland with coarse gravel (HSFCW-C). We made tracer measurements: Inside a constructed wetland, we had 9 sample points, and samples were taken from each point at two depths. Our model is a divided convective-dispersive transport (D-CDT) model which makes a fitted response curve from the sum of two separate CDT curves showing the contributions of the main and side streams. Analytical solutions of CDT curves are inverse Gaussian distribution functions. This model was fitted onto inner points of the measurements to demonstrate that the model gives better fitting to the inner points than the commonly used convective-dispersive transport model. The importance of this new application of the model is that it can resemble transport processes in these constructed wetlands more precisely than the regularly used convective-dispersive transport (CDT) model. The model allows for calculations of velocity and dispersion coefficients. The results showed that this model gave differences of 4–99% (of velocity) and 2–474% (of dispersion coefficient) compared with the CDT model and values were closer to actual hydraulic behavior. The results also demonstrated the main flow path in the system.

We measured the daily evapotranspiration on a horizontal sub-surface flow constructed wetland in Hódmezővásárhely, Hungary. The main focus of our research was the seasonality of evapotranspiration in this CW. We measured the water balance of the CW and searched days when no precipitation, no inlet or outlet impacted on the water balance of the constructed wetland, only the evapotranspiration. had impact on the water balance. The results show that in spring the evapotranspiration rates were between 18-42,6 mm/day, in summer 12,3-42,3 mm/ day and in autumn the values were 13,6-22,7 mm/day. The highest hourly evapotranspiration was 16,3% of the daily evapotranspiration. This value was 415 % of the average, hourly hydraulic load that can significantly affects on the effluent concentration. The results also show the morning and evening condensation which has two main effects. On the other hand, the water balance of the CW is increased, which results the decrease of the concentration of wastewater.

As organic manure is becoming less available, using different materials as soil fertilizers and the application of the inorganic fertilizers raises many questions. Therefore, it is increasingly important to use compost and biogas digestate to improve soil quality. The activity of the microbial communities ensures the fertility of the soil. One of the most important enzymes is dehydrogenase. This enzyme group catalyses the hydrogen transfer in the process of biological oxidation. Our aim was to examine the effect of biogas digestate on dehydrogenase enzyme activity (DHA) in 3 different types of soil. Hungarian standard method was used to evaluate DHA. The applied biogas digestate was obtained from the Kaposvár Sugar Factory of Hungarian Sugar Ltd. The dose is equal to 16,7 m3ha-1 and 533 kg organic matterha-1. The treatment was performed in three different groups of soil: brown forest soil, calcareous chernozem and carbonate meadow soil. The results showed an increase in DHA in all types of soil. DHA values were the highest in case of the carbonate meadow soil, specifically 0.337 mg formazan/1 g soil/24 h immediately after the treatment and 0.410 after 28 days. A critical aspect to consider during the construction of biogas plants is the soil protection agency’s ban on using soil fertilizers during the winter months. Analysis carried out according to the protocol of sewage sludge examination revealed that biofermentate produced during biogas generation does not contain any environmentally harmful components. After the elaboration of a soil protection plan, the recommended way to apply biogas digestate to arable land is via injectors.