The use of sludge in agriculture within the European Union (EU) is currently regulated only by the limits of heavy metals (Cd, Cu, Hg, Ni, Pb and Zn) listed in Council Directive 86/278/EEC. This document is now more than 30 years old. Several European countries have introduced more stringent requirements in comparison with the directive, and have adopted limits for concentrations of other heavy metals, synthetic organic compounds and microbial contamination. The paper provides an overview of the current limits of these substances in sewage sludge and concentration limits of heavy metals in soil intended for sludge application, together with applicable laws and regulations in European Union countries. There is a need to update these regulations taking into account the current risks associated with the application of sludge to agricultural land, with the possibility of using ecotoxicological tests to assess the risks. A wide range of technologies for sewage sludge processing is used in EU countries. The predominant choice is a direct application in agriculture followed by composting. The use of sewage sludge in agriculture in 2014 and 2015 in 13 EU countries that provided data amounted to 22.6% (2014) and 22.1% (2015) of produced sludge and 23.3% (2014) and 23.1% (2015) of sludge disposed. It is also highly variable within EU countries ranging between zero (Malta, Slovenia, Slovakia) and 80% (Ireland). Over 50% of sewage sludge is used in agriculture in Bulgaria according to 2015 data.

The paper presents a map of historical ponds of the whole Czech Republic which was created on

Všetičková L., Adámek Z., Rozkošný M., Sedláček P. 2012. Effects of semi-intensive carp pond farming on discharged water quality. Acta Ichthyol. Piscat. 42 (3): 223-231.Background. Fish pond management can substantially modify the hydrological regime and ecological quality of receiving waters (usually rivers, canals, and ponds downstream in an interconnected system) with potentially positive or negative impacts on watershed functioning. To evaluate these effects with respect to carp pond management, the environmental impacts of semi-intensive farming on discharged water quality were monitored at four differently managed carp ponds, differing in trophic status (two eutrophic and two hypertrophic ponds). Materials and methods. Fundamental determinants of pond inflow and outflow water quality were monitored monthly from April to October 2009. Water temperature, pH, and dissolved oxygen concentration and saturation were measured in situ whilst hydrochemical and microbiological parameters were assessed in the laboratory.Results. Compared to the inflow water, in the effluents there was a significant decline in numbers of bacterial loading indicators (Escherichia coli, enterococci, faecal coliform and mesophilic bacteria) in the outflow water. In ponds with the poor quality inflow water (downstream of water treatment plant discharges), a significant decrease was also registered in nutrients (N-NH 4 , N-NO 3 , total nitrogen, P-PO 4 , and total phosphorus) and organic loads? (five-day biological oxygen demand, chemical oxygen demand) of pond effluents. At the pond supplied with good quality river water, however, the same determinants showed that effluent water quality worsened significantly. Total organic carbon and suspended solids increased in effluents of ponds with high fish biomass stocked.Conclusion. The results demonstrate that, during the growing season, properly managed carp ponds represent ecosystems with high self-cleaning ability. They may play an important role in the nutrient balance, storage and trapping in agricultural landscape with high population density.

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Agriculture is being negatively affected by the decrease in precipitation that has been observed over the last few years. Even in the Czech Republic, farmers are being urged to irrigate their fields despite the fact that sources of water for irrigation are rapidly being depleted. This problem might be partially solved via the reuse of treated wastewater in certain agricultural sectors. However, the public perception of the reuse of wastewater remains negative primarily due to unknown risks to the environment and public health. To overcome this barrier, a semi-operated irrigation field was established at Kostelec nad Ohří in the Central Bohemian region of the Czech Republic and planted with common garden crops such as tomatoes (Lycopersicon esculentum), potatoes (Solanum tuberosum) and lettuces (Lactuca sativa L.) irrigated with two different water sources, i.e., treated wastewater from a local nature-based treatment system, a hybrid constructed wetland (HCW), and local fresh water from well. The HCW was put into operation in 2017 and was reconstructed in 2018 and includes both horizontal and vertical flow beds; the trial irrigation field was added in the same year. The reconstruction of the facility significantly enhanced the removal efficiency with respect to all monitored parameters, e.g., biochemical oxygen demand (BOD5), chemical oxygen demand (COD), N–NH4+, total N and the suspended solids (TSS), except for total P. The HCW also ensured the significant removal of several observed pathogenic microorganisms (E. coli, intestinal enterococci and thermotolerant coliforms). During the 2018 and 2019 growing seasons, we observed the significantly enhanced growth of the crops irrigated with wastewater from the HCW due to the fertilizing effect. The risks associated with the contamination of crops irrigated with treated water are not negligible and it is necessary to pay sufficient attention to them, especially when introducing irrigation with wastewater into practice.