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Eutrophication is the state with high nutrient concentration, which can cause plant growth including algae blooms. Nutrients drain into the Baltic Sea from agricultural lands and drainage systems, from weak or insufficient wastewater treatment, from contaminated industrial waste water, and even from the rain water, if it contains dust, unburnt oil from the roads and parking areas or other pollutants washed from hard coverings or accumulated in the air. High nutrient level into the natural waters affects the human economic activity. An inexpensive way to reduce nutrient load to water objects from agricultural lands is formation of constructed wetlands or restoration of natural wetlands. The main tasks of this study were to describe the processes in constructed wetlands, the conditions of construction and to analyze the capacity of constructed wetlands to reduce nutrients and suspended particles inflow to open waters. Another task was to determine nutrient retention efficiency in the Mežacīruļi constructed wetland in Latvia by the descriptive methods of mathematical statistics and Wilcoxon T test method and to compare the obtained results with ones from Bergaholm constructed wetland in Sweden. In the end of this article, the evaluation of efficient theoretical design parameters for constructed wetlands in Latvia is made. The research results indicate that the Mežacīruļi constructed wetland does not provide the sufficient nutrient retention. To improve the nutrient retention efficiency, it would be necessary to develop it, e.g., to increase the amount of vegetation, such as planting Typha spp. or to make a small constructed wetland extension to a depth of 0.3 m for Carex spp. to stabilize the sediments. [ABSTRACT FROM AUTHOR]

A pilot-scale horizontal subsurface flow constructed wetland was installed at the farm Mezaciruli, Zalenieki county, Jelgava region, in the middle part of Latvia, in August 2014 to improve stormwater quality collected from the farmyard and demonstrate applicability of constructed wetland as a convenient treatment option for contaminated surface runoff. The examined water treatment system consists of a sedimentation pond as a pretreatment plant, a water pump, a water distribution well, and a horizontal subsurface flow constructed wetland with the surface area of 160 m². During the observation period of 27 months (2014 - 2016) water quality parameters such as total suspended solids (TSS), nitrate nitrogen (NO3-N), ammonium nitrogen (NH4-N), total nitrogen (TN), orthophosphate phosphorus (PO4-P), and total phosphorus (TP) were monitored and nutrient removal efficiency of the system was examined. Water samples collected at the inlet and outlet were compared. Monitoring results obtained during this study show that on average concentrations of TN and TP were reduced by 22% and 80%, respectively. However, nitrate - nitrogen concentrations on average increased by 10%, as during the time period from June, 2015 to March, 2016 reduction in NO3-N concentrations was not observed. [ABSTRACT FROM AUTHOR]

The research site consists of a pilot-scale surface flow constructed wetland at the farm Mezaciruli located in Zalenieki County, Jelgava Region, in the middle part of Latvia. The constructed wetland was installed in June 2014 to improve water quality in agricultural catchment and examine nutrient retention at the constructed wetland receiving surface and drainage runoff. The constructed wetland's surface area of 0.37 ha corresponds to 0.5 % of the total catchment area. During the observation period of 32 months (2014-2017) water quality parameters such as total suspended solids (TSS), nitrate-nitrogen (NO3-N), ammonium-nitrogen (NH4-N), total nitrogen (TN), orthophosphate-phosphorus (PO4-P), and total phosphorus (TP) were monitored twice a month using a grab sample approach. Retention efficiency for monitored water quality parameters was calculated based on their concentrations at the inlet and out let. The monitoring results obtained during this study showed a reduction within the constructed wetland for all examined parameters. The concentrations of NO3-N, NH4-N and TN were reduced on average by 13 %, 15 % and 16 %, respectively. PO4-P and TP concentrations were reduced on average by 38 % and 36 %, respectively. Total suspended solids were reduced by 31% at the outlet of the constructed wetland. However, in some cases, an increase in nutrient concentrations in water leaving the constructed wetland was observed. Therefore, there is a need for further research to investigate causes of such increase. [ABSTRACT FROM AUTHOR]

Usually in wastewater treatment plants the removal of organic matter is ensured in aerotanks in biochemical reactions where activated sludge in presence of oxygen transforms the organic matter. The quantity of organic matter in water can be determined as the biochemical oxygen demand in five days (BOD). BOD in village municipal sewage is around 250 mg l-1 or 65 g per day from each resident. It means that 1.7 kg of oxygen is needed for mineralizing one kg of organic matter. Therefore, it can be concluded that high oxygen demand is required to mineralize organic matter using aerotanks. With a compressor and aeration discs or tubes the oxygen in the form of air is provided to aerotank. To reduce electricity consumption in wastewater treatment, we present to adapt natural conditions. Mineralization of organic matter in constructed wetlands performs basing on bacteria activity in presence of oxygen. The main difference is the method for oxygen supply. In constructed wetlands oxygen demand provides the plants growing above the filter material and it consumes no electricity. Constructed wetlands can be designed with different water flow in filter material - horizontal flow wetlands, vertical flow wetlands and shallow ponds with plants. [ABSTRACT FROM AUTHOR]

Population growth in coastal areas worldwide call for new challenges to be solved. Blue growth initiatives are elaborated and developed in order to prevent sea resources depletion unsustainably by fishing, mining, transportation, tourism, and waste. The EU Water Framework Directive (2000/60/EC), EU Groundwater Directive (2002/118/EC) as well as EU Waste Framework Directive (2006/12/EC) are the legislative tools that base the pillars for more detailed action plans that prevents contamination spread, promote clean-up and drives us to sustainable solutions. In EC there are Joint Research Centre (JRC) for Land Management and Natural Hazards Unit to encourage the development and broader use of environmental technologies, including environmental remediation technologies. This paper aims to give different best practices to solve individual cases similarly as in The Network for Industrially Contaminated Lands in Europe (NICOLE), The European Coordination Action for Demonstration of Efficient Soil and Groundwater Remediation (EURODEMO) projects decades ago which also promoted cost-effective soil and groundwater remediation technologies, unifying efforts for joint European Sustainable Development Strategies. Baseline studies and pilot scale test-fields were developed in Baltic Sea Region with Triple helix approach that implements collaboration among stakeholders (firms, authorities and scientists). Interregional collaboration projects on Blue Economy and Sustainable Growth such as “Reviving Baltic Resilience” (RBR), “Enhancement of Green Infrastructure in the Landscape of Lowland Rivers” (ENGRAVE), “Baltic Beach Wrack - Conversion of a Nuisance To a Resource and Asset” (CONTRA) as well as Swedish Institute knowledge exchange project LASUWAMA are just a few examples how to disseminate good practices and implement in local and regional levels. Sustainability and circular economy are steps forward to green innovation revolution [ABSTRACT FROM AUTHOR]

It is generally estimated that gas, which generates more than half of the greenhouse gas (GHG) emission from waste industries in landfills, is seen as a serious environmental problem worldwide. It is therefore essential to promote management methods to reduce GHG emissions from landfills as well as other sources. One way of achieving this is the usage of different types of biocover applied to them. The aim of this study is to clarify the impact of the biocover created on GHG emissions. An experiment was conducted in laboratory conditions that studied the effectiveness of biocover developed in the laboratory. Three experimental columns with a diameter of 160 mm and a height of 1500 mm were created. Active compost saturated with water at a thickness of 500 mm was used as a source of methane, a permeable layer of sand at a thickness of 300 mm was further formed and finally covered with biocover. Biocover represented 60% of fine-fraction waste, 20% of soil and 20% of compost. The experiment was launched on June 6, 2022, and the first measurements were made two weeks later. All measurements were performed with the CRDS gas measurement device Picarro G2508 (Picarro Inc., USA California). All data analysis was carried out using Descriptive statistics methods. The largest reduction in emissions is projected directly for methane emissions, as biocover technology is appropriate to reduce methane emissions. Other GHG emissions are also expected to be reduced. NH3 emission measurements were also carried out to investigate the impact of the biocover on it. This experiment shows that the biocover created is effective and can be composed of material that has already been served. The experiment is intended to continue to obtain long-term data on the development of biotransformation and to develop more promising approaches in the future to reduce GHG emissions from landfills [ABSTRACT FROM AUTHOR]

Commonly the product’s life cycle ends up with waste. Conventionally the remains go to the landfill, earlier times – a dumpsite, the least manageable waste disposal method. To ensure that lost to society materials are treated with high priority, the European Union (EU) has implemented the Circular Economy Action Plan, continuing the monitoring of old dumpsites. The hierarchy of waste management points at preventing raw material use at first sight, but the following steps point at material reuse and recycling. The material recovery and revitalisation of old forgotten dumpsites are related to a sustainable and circular economy based direction and the corresponding rules. Candidates for so-called landfill mining (LFM) should be evaluated on a country by country basis. The starting point is inspecting each dumpsite, evaluating prospective materials and space as the real estate benefit and landscapes revitalisation perspective. Another aspect is the emissions diminishment while an innovative approach of landfill closing is taken. A fine fraction of residual waste might be used as a cover – functional composite capping material. It would decrease methane gas emissions in the atmosphere. Last but not least is restoring ecosystem services by revitalising the dump structures as parks and recreation areas and/or transforming them to industry/logistic parks to diminish the need for new urban areas in virgin lands. This study aims to analyse the aspects compulsory when estimating old dumpsites revitalisation projects. [ABSTRACT FROM AUTHOR]