The potential for water recovery from urban waste water - The perspective of urban waste water treatment plant operators in Poland.

Water recovery from waste water has become an essential element of the circular economy in the Baltic Sea region. However, there is little data on the possibility of using water recovered from urban waste water. A survey was conducted to learn the opinions of Poland waste water treatment plant operators. They were asked whether they recovered water for internal or external needs. Respondents indicated opportunities and barriers in this activity. The opinions of 107 operators show that work is underway on closing internal circuits in urban WWTPs. These solutions are technically relatively easy to implement and show measurable benefits (i.e., saving drinking water). However, water recovery for external purposes is rare and is at a very early stage. Despite this, the potential is significant, although many financial, organizational, technical, and mental barriers exist. The most critical challenge is the safe use of reclaimed water and the cost-effectiveness of the solutions. The survey also shows a need for education and involvement of the public.

Investigating phosphorus loads removed by chemical and biological methods in municipal wastewater treatment plants in Poland.

The article presents an analysis of the current methods for phosphorus removal applied in municipal wastewater treatment plants in Poland. Within the study, 131 wastewater treatment plants were investigated, constituting 17 630 500 population equivalent, which is about 1/3 of the overall population equivalent (designed) in Poland. The research was based on a detailed technical questionnaire analysis obtained from wastewater treatment plants operators and calculations of pure metal doses in the applied coagulants and their type per a treated wastewater volume, population equivalent and phosphorus load removed. Moreover, a basic statistical analysis based on Pearson's correlation coefficient was applied to validate the relationship between the consumption of coagulants per the removed P load and the treated wastewater volume in 3 categories of wastewater treatment plants in terms of their population equivalent. The analysis results show that a minimum of 1470 Mg of phosphorus removed by 35 wastewater treatment plants based entirely on biological treatment methods could be used for phosphorus recovery to produce struvite, calcium phosphate or other highly bioavailable alternative fertilizer products. Moreover, 1490 Mg of phosphorus removed by other 17 wastewater treatment plants with a minimal coagulant dose (<1 g of metal per m3 of wastewater), increases the base for phosphorus recovery to approx. 2960 Mg per year using sewage sludge or its dewatering liquors. These results suggest that the implementation of the means mentioned above would significantly increase the possibilities for obtaining phosphorus from secondary sources, especially in wastewater treatment plants without sewage sludge incineration plants.

Indicators for resource recovery monitoring within the circular economy model implementation in the wastewater sector.

The European Union is currently in the process of transformation toward a circular economy model in which different areas of activity should be integrated for more efficient management of raw materials and waste. The wastewater sector has a great potential in this regard and therefore is an important element of the transformation process to the circular economy model. The targets of the circular economy policy framework such as resource recovery are tightly connected with the wastewater treatment processes and sewage sludge management. With this in view, the present study aims to review existing indicators on resource recovery that can enable efficient monitoring of the sustainable and circular solutions implemented in the wastewater sector. Within the reviewed indicators, most of them were focused on technological aspects of resource recovery processes such as nutrient removal efficiency, sewage sludge processing methods and environmental aspects as the pollutant share in the sewage sludge or its ashes. Moreover, other wide-scope indicators such as the wastewater service coverage or the production of bio-based fertilizers and hydrochar within the wastewater sector were analyzed. The results were used for the development of recommendations for improving the resources recovery monitoring framework in the wastewater sector and a proposal of a circularity indicator for a wastewater treatment plant highlighting new challenges for further researches and wastewater professionals.

Trends, insights and effects of the Urban Wastewater Treatment Directive (91/271/EEC) implementation in the light of the Polish coastal zone eutrophication.

The intensification of the Baltic Sea eutrophication is associated with the increase of anthropogenic nutrients loads, mainly nitrogen and phosphorus introduced into surface waters from a diffuse, point and natural background sources. Despite the observed decreasing trends in nutrient concentrations in some parts of the Baltic Sea, eutrophication-related indicators continue to deteriorate. This accelerates harmful algal blooms and dissolved oxygen deficits resulting in severe ecosystem disturbance. The paper presents trends, insights and effects of the Urban Wastewater Treatment Directive 91/271/EEC implementation in Poland based on the nutrient riverine loads from Polish territory with particular attention given to the development of municipal wastewater treatment plants under the National Wastewater Treatment Programme 2003-2016. Environmental effects of wastewater infrastructure modernisation are investigated by using available data on the changing nutrient concentrations in the coastal water in 3 basins (Gdansk Basin, Bornholm Basin and Eastern Gotland Basin) belonging to the Polish Exclusive Economic Zone within the Baltic Sea. The results show that the decreasing trend regarding phosphorus loads reduction from municipal effluents was achieved while a stable trend with temporary increases was achieved in terms of nitrogen loads. Moreover, the investigation provides information about the potential bioavailability of discharged effluents before and after the Directive implementation by including total and inorganic forms of nitrogen and phosphorus in the analysis.

Inventory of Polish municipal sewage sludge ash (SSA) - Mass flows, chemical composition, and phosphorus recovery potential.

This paper presents an inventory of sewage sludge ashes (SSA) generated in the mono-incineration plants for municipal sewage sludge in Poland. This research focused on the detailed study of mass flows, chemical composition, and phosphorus recovery potential. There are currently 11 sludge mono-incineration plants operated with a total capacity of 160,300 Mg dry weight (d.w.) of sludge annually. Recently, a significant increase in the amount of SSA generated in these plants has been observed, reaching 26,756 Mg in 2018. Chemical composition of SSA showed significant amounts of the main nutrients: calcium (~14%), phosphorus (~13%), magnesium (~3%), and potassium (~1%). Additional main elements were iron (~14.5%), silicon (~13%), and aluminium (~6%). The main trace elements in the SSA were zinc (~3750 mg/kg) and copper (~899 mg/kg). Pollutants, according to fertilizer regulations of different countries, present in Polish SSA were chromium (~703 mg/kg), nickel (~260 mg/kg), lead (~94 mg/kg), and cadmium (~9 mg/kg). The radionuclides, uranium, and thorium often present in higher amounts in commercial phosphate rock-based fertilizers, were only detected in SSA at low levels of 4-9 mg/kg and 2-3 mg/kg, respectively. Theoretical phosphorus recovery potential from the SSA (from plants in Cracow, Lodz, Gdansk, Gdynia, Szczecin, and Kielce) was estimated at 1613.8 Mg, of which 33.9% is bioavailable. Currently, in Poland, the recommended approach is the production of fertilizers as a result of the extraction of phosphorus from the SSA with its use in the production of secondary mineral fertilizers. Further research in this area is required considering Polish conditions and legislation.

The efficiency and economic aspects of phytoremediation technology using Phalaris arundinacea L. and Brassica napus L. combined with compost and nano SiO2 fertilization for the removal of PAH's from soil.

The paper presents an evaluation of efficiency and economic potential of the phytoremediation technology, based on the use of energy crops (P. arundinacea L. and B. Napus L.), combined with the fertilization with compost, supported by the addition of nano SiO2. The experiment was conducted in in-situ conditions, using two experimental blocks, divided according to used plant species. Each block included four types of plots with different fertilization treatments (control plots; treatment with nano SiO2; treatment with compost; treatment with mixture of compost and nano SiO2). During the studied period (three vegetation seasons), a cyclic analysis of 16 PAH's content were conducted. Furthermore, a quantitative determination of biomass production was performed as well as assessment of economic potential of different strategies. Data collected during research, shows that method based on energy crops use, due to the join effect of the dangerous pollutants removal and the production of removable energy resource, can be considered as sustainable and should be recommended for use during heavy polluted soil remediation. Moreover, it should be also noted, that the best results for both PAH's removal efficiency and biomass production, were acquired on plots with P. arundinacea L. cultivation, fertilized with mix of compost and nano SiO2.

Influence of Integrated Membrane Treatment on the Phytotoxicity of Wastewater from the Coke Industry.

In this paper, coke wastewater that had passed through biological and integrated membrane processes (filtration on sand bed-reverse osmosis) was chosen to assess the phytotoxicity of selected industrial wastewater with regard to the test plant-Vicia faba. An innovative research technique in vitro test was conducted in a large scale phytothrone chamber on two matrices: cotton and Murashige and Skoog Basal Medium (MSBM). The toxicity of wastewater was evaluated for samples: (1) treated in the treatment plant by biological processes, (2) filtrated through a sand bed and filtrated (3) reverse osmosis (RO) membrane. The results showed that there is a noticeable correlation between increasing concentrations of wastewater and seed germination of the test plant. Although the wastewater collected from the coke plant was treated biologically, it showed very high levels of germination inhibition (90-98% for cotton matrix and 92-100% for MSBM matrix) and strong toxic effects. The wastewater collected from the coke plant showed a significantly greater phytotoxic effect compared with those obtained from the effluent treated on a sand bed and in RO. However, wastewater, even after treatment on a sand bed (reduction of COD-39%, TN-46%, TOC-42%, TC-47%, SS-50%, 16PAHs-53%), was still toxic and germination inhibition was in the range of 24-48% for the cotton matrix and 14-54% for the MSBM matrix. The toxicity of wastewater treated in the membrane process was the lowest (reduction of COD-85%, TN-95%, TOC-85%, TC-86%, SS-98%, 16PAHs-67%). The germination inhibition was in the range of 4-10% for the cotton matrix and 2-12% for the MSBM matrix. These samples are classified as non-toxic or slightly toxic to the model plant. The present study highlights the necessity of monitoring not only the basic physical and chemical indicators (including the level of toxic substances as PAHs), but also their effect on the test organisms in wastewater samples.

The evaluation of polycyclic aromatic hydrocarbons (PAHs) biodegradation kinetics in soil amended with organic fertilizers and bulking agents.

The aim of this study was to investigate the polycyclic aromatic hydrocarbons (PAHs) biodegradation kinetics in soils fertilized with organic amendments (sewage sludge, compost), bulking agents (mineral sorbent, silicon dioxide in form of nano powder), and novel compositions of those materials. The scope of conducted works includes a cyclic CO2 production measurements and the determinations of PAHs content in soil samples, before and after 3-months of incubation. Obtained results show that the use of both type of organic fertilizers have a positive effect on the PAHs removal from soil. However, the CO2 emission remains higher only in the first stage of the process. The best acquired means in terms of PAHs removal as well as most sustained CO2 production were noted in samples treated with the mixtures of organic fertilizers and bulking agents. In conclusion the addition of structural forming materials to the organic fertilizers was critical for the soil bioremediation efficiency. Therefore, the practical implementation of collected data could find a wide range of applications during the design of new, more effective solutions for the soil bioremediation purposes.

Fertilisers production from ashes after sewage sludge combustion - A strategy towards sustainable development.

Sustainable development and circular economy rules force the global fertilizer industry to develop new phosphorous recovery methods from alternative sources. In this paper a phosphorus recovery technology from Polish industrial Sewage Sludge Ashes was investigated (PolFerAsh - Polish Fertilizers form Ash). A wet method with the use of mineral acid and neutralization was proposed. Detailed characteristic of SSA from largest mono-combustion plans were given and compared to raw materials used on the market. The technological factors associated with such materials were discussed. The composition of the extracts was compared to typical industrial phosphoric acid and standard values characterizing suspension fertilizers. The most favorable conditions for selective precipitation of phosphorus compounds were revealed. The fertilizers obtained also meet EU regulations in the case of the newly discussed Cd content. The process was scaled up and a flow mass diagram was defined.

Sewage sludge ash (SSA) from large and small incineration plants as a potential source of phosphorus - Polish case study.

The aim of this research is to present the possibility of using the sewage sludge ash (SSA) generated in incineration plants as a secondary source of phosphorus (P). The importance of issues related to P recovery from waste materials results from European Union (UE) legislation, which indicated phosphorus as a critical raw material (CRM). Due to the risks of a shortage of supply and its impact on the economy, which is greater than other raw materials, the proper management of phosphorus resources is required in order to achieve global P security. Based on available databases and literature, an analysis of the potential use of SSA for P-recovery in Poland was conducted. Currently, approx. 43,000 Mg/year of SSA is produced in large and small incineration plants and according to in the Polish National Waste Management Plan 2014 (NWMP) further steady growth is predicted. This indicates a great potential to recycle phosphorus from SSA and to reintroduce it again into the value chain as a component of fertilisers which can be applied directly on fields. The amount of SSA generated in installations, both large and small, varies and this contributes to the fact that new and different P recovery technology solutions must be developed and put into use in the years to come (e.g. mobile/stationary P recovery installations). The creation of a database focused on the collection and sharing of data about the amount of P recovered in EU and Polish installations is identified as a helpful tool in the development of an efficient P management model for Poland.