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Funding Information: The authors acknowledge the support provided by InterPhD2 Program funded by European Union/European Social Fund (Project No. POWR.03.02.00-IP.08-00-DOK/16). The authors would like to further thank ?Finnish Water Utilities Development Fund? that provided funding for the project ?Carbon Footprint of Finnish Wastewater Treatment Plants?. Funding Information: The authors acknowledge the support provided by InterPhD2 Program funded by European Union / European Social Fund (Project No. POWR.03.02.00-IP.08-00-DOK/16 ). The authors would like to further thank “Finnish Water Utilities Development Fund” that provided funding for the project “Carbon Footprint of Finnish Wastewater Treatment Plants”. Publisher Copyright: © 2021 The Authors Finland and Poland share similar environmental interests with regard to their wastewater effluents eventually being discharged to the Baltic Sea. However, differences in the influent wastewater characteristics, treatment processes, operational conditions, and carbon intensities of energy mixes in both countries make these two countries interesting for carbon footprint (CF) comparison. This study aimed at proposing a functional unit (FU) which enables a comprehensive comparison of wastewater treatment plants (WWTPs) in terms of their CF. Direct emissions had the highest contribution (70%) to the total CF. Energy consumption dominated the total indirect emissions in both countries by over 30%. Polish WWTPs benefitted more from energy self-sufficiency than Finnish plants as a result of higher electricity emission factors in Poland. The main difference between indirect emissions of both countries were attributed to higher chemical consumption of the Finnish WWTPs. Total pollution equivalent removed (TPErem) FU proposed enabled a better comparison of WWTPs located in different countries in terms of their total CF. High correlations of TPErem with other FUs were found since TPErem could balance out the differences in the removal efficiencies of various pollutants. Offsetting CF was found a proper strategy for the studied WWTPs to move towards low-carbon operation. The studied WWTPs could reduce their CF from up to 27% by different practices, such as selling biofuel, electricity and fertilizers. These findings are applicable widely since the selected WWTPs represent the typical treatment solutions in Poland, Finland and in the Baltic Sea region.

There is an increased focus on ensuring optimal use of the resources of the planet. However experience shows that legislation can hinder the use of the resources from waste. This report examines th ...

The growth of Finnish extractive industry increases the need to study and monitor different environmental impacts and to integrate the environmental issues more tightly into the overall framework of the activities. Nitrogen released from explosives or from mining processes and ending up in the water system can have negative environmental effects. The MINIMAN project, financed by the Tekes Green Mining Programme and the industry aimed at comprehensive understanding on the nitrogen issue in the extractive industry. The project collected essential data on nitrogen compounds present in the environments of mines and quarries, and developed technologies for the treatment of nitrogen containing mine water. Based on a technology review, selective sorption, electrochemically assisted membrane separation and biological treatment were selected to be studied and developed in the project. Denitrification and nitrification studies on synthetic mine wastewater in laboratory scale revealed that denitrification was possible at low pH (2.5) and temperatures as low as 7°C. Nitrification was more pH sensitive. Both processes tolerated metals (Fe, Ni, Co and As). In the adsorption tests with zeolite, complete ammonium removal from real mine wastewater was achieved with a hydraulic retention time of 2 minutes, with complete regeneration. In addition, a novel electropervaporative nitrogen capture technology was developed. Further larger scale testing and development of all technologies is required to ensure their feasibility in a real mining site. A follow-up period in lysimeters showed that the explosives originated nitrogen content of left over stones from natural stone quarrying is relatively low and ca. half of the nitrogen is leached within the first weeks after detonation. The main sources of nitrogen are process and dewatering waters, irrespective of the scale of extractive activity. The total potential nitrogen load to the environment depends on the scale and type of the activity as well as the type of explosives used. In addition to factors related to the activity itself, the overall nitrogen management should take into account the background concentrations and sensitivity of the local ecosystem.

Pneumatic waste collection systems are becoming increasingly popular in new urban residential areas, and an attractive alternative to conventional vehicle-operated municipal solid waste (MSW) collection also in ready-built urban areas. How well pneumatic systems perform in ready-built areas is, however, an unexplored topic. In this paper, we analyze how a hypothetical stationary pneumatic waste collection system compares economically to a traditional vehicle-operated door-to-door collection system in an existing, densely populated urban area. Both pneumatic and door-to-door collection systems face disadvantages in such areas. While buildings and fixed city infrastructure increase the installation costs of a pneumatic system in existing residential areas, the limited space for waste transportation vehicles and containers cause problems for vehicle-operated waste collection systems. The method used for analyzing the cost effects of the compared waste collection systems in our case study takes into account also monetized environmental effects of both waste collection systems. As a result, we find that the door-to-door collection system is economically almost six times more superior. The dominant cost factor in the analysis is the large investment cost of the pneumatic system. The economic value of land is an important variable, as it is able to reverse the results, if the value of land saved with a pneumatic system is sufficiently high.

Waste collection is one of the life cycle phases that influence the environmental sustainability of waste management. Pneumatic waste collection systems represent a new way of arranging waste collection in densely populated urban areas. However, limited information is available on the environmental impacts of this system. In this study, we compare the environmental sustainability of conventional door-to-door waste collection with its hypothetical pneumatic alternative. Furthermore, we analyse whether the size of the hypothetical pneumatic system, or the number of waste fractions included, have an impact on the results. Environmental loads are calculated for a hypothetical pneumatic waste collection system modelled on an existing dense urban area in Helsinki, Finland, and the results are compared to those of the prevailing, container-based, door-to-door waste collection system. The evaluation method used is the life-cycle inventory (LCI). In this study, we report the atmospheric emissions of greenhouse gases (GHG), SO2 and NOx. The results indicate that replacing the prevailing system with stationary pneumatic waste collection in an existing urban infrastructure would increase total air emissions. Locally, in the waste collection area, emissions would nonetheless diminish, as collection traffic decreases. While the electricity consumption of the hypothetical pneumatic system and the origin of electricity have a significant bearing on the results, emissions due to manufacturing the system’s components prove decisive.

The role of sludge in renewable energy production and the final disposal of sludge are topical issues. The cost of sludge treatment account for a significant share of the total running costs of a WWTP. By increasing the efficiency of sludge treatment, significant savings can be achieved. Savings can be gained e.g. by more efficient energy utilisation of sludge, combined with optimised wastewater treatment processes. In addition to cost efficiency, environmental sustainability of the applied solutions is crucial. The energy balance and green house gas emissions can be used as tools to evaluate the sustainability of sludge treatment options. This paper presents a case-based comparison of energy balances, green house gas emissions and costs of municipal wastewater sludge process chains based on anaerobic digestion or incineration. Information from existing plants was used for conducting the study. Several utilisation options were covered for biogas energy as well for energy from sludge incineration. Based on the results, sludge incineration was the most expensive option of the studied scenarios, but justified if the heat generated can be fully utilised e.g. in district heating. Based on costs and energy balances as well as green house gas emissions it is most preferable in anaerobic digestion chains to feed the generated biogas to a gas engine to produce electricity and heat. Moreover, thermophilic anaerobic digestion can improve the overall economy of a WWTP provided that the biogas yield is sufficiently higher than in a mesophilic process. However increased odour is a risk in thermophilic digestion. The study showed that the most energy efficient process modifications are always very case bound. However the tools developed in this study are generally applicable to waste water treatment plants for similar analyses.

Valmiiksi rakennetulla kaupunkialueella jätteiden putkikuljetus on vielä kyseenalainen, mutta kehityskelpoinen jätteenkeräysratkaisu. Helsingin yliopiston taloustieteen laitoksen ja VTT:n tutkimuksessa tarkasteltiin putkikuljetuksen kilpailukykyä Helsingin Punavuoressa. Aihetta lähestyttiin yhteiskunnallisesta näkökulmasta. Tutkimuksessa keskityttiin vertaamaan putkikuljetuksen ja perinteisen astiakeräyksen elinkaaren aikaisia ympäristökuormituksia sekä yhteiskunnalle koituvia kustannuksia. Tulosten perusteella mallinnetun kaltaista putkikuljetusjärjestelmää ei voida nykyisellään pitää yhteiskunnan kannalta kilpailukykyisenä jo rakennetun alueen jätteenkeräysratkaisuna. Herkkyystarkastelu kuitenkin osoittaa, että putkikuljetuksen yhteiskunnalliset kustannukset saattavat alentua merkittävästikin, mikäli järjestelmän voidaan olettaa vapauttavan arvokasta tilaa kaupunkialueelta. Putkikuljetuksen kilpailukyvyn voidaan myös olettaa paranevan vanhallakin kaupunkialueella, kun putkikuljetusjärjestelmät kehittyvät teknisesti ja niistä saadaan lisää käyttökokemusta. Tutkimuksessa ei kyetty ottamaan huomioon kaikkia putkikuljetuksen eduiksi katsottuja vaikutuksia, jotka saattavat olla suuret vanhalla asuinalueella ja siten tasoittaa putkikuljetuksen ja astiakeräyksen kannattavuuden välistä eroa. Tutkimus toteutettiin osana Tekesin rahoittamaa SUSWASTE-hanketta, jossa pyrittiin kartoittamaan tulevaisuuden kestäviä liiketoimintamahdollisuuksia jätehuoltoalalla