Erkki Hiltunen

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An integrated approach, which combined freshwater microalgae Chlorella zofingiensis cultivation with piggery wastewater treatment, was investigated in the present study. The characteristics of algal growth, lipid and biodiesel production, and nutrient removal were examined by using tubular bubble column photobioreactors to cultivate C. zofingiensis in(More)
Harvest water recycling for Chlorella zofingiensis re-cultivation under nutrient limitation was investigated. Using 100% harvest water, four cultures were prepared: Full medium, P-limited medium, N-limited medium and N- and P-limited medium, while another full medium was also prepared using 50% harvest water. The results showed that the specific growth rate(More)
Scale-up potential of cultivating Chlorella zofingiensis in piggery wastewater for simultaneous wastewater treatment and biodiesel production was tested. The cultivation of C. zofingiensis with autoclaved wastewater and NaClO-pretreated wastewater, cultivation of algae indoors and outdoors, and stability of semi-continuous feeding operation were examined.(More)
In response to the energy crisis, global warming, and climate changes, microalgae have received a great deal of attention as a biofuel feedstock. Due to a high lipid content in microalgal cells, microalgae present as a promising alternative source for the production of biodiesel. Environmental and culturing condition variations can alter lipid production as(More)
Constructed wetlands (CWs) are efficient in reducing excessive contamination from wastewaters. However, oxygen inside CW beds is frequently low especially when substrate clogging problems appear after long-term operation, and this may become a limited factor for the treatment of wastewaters. Aimed at dealing with the issue of a low oxygen content in CW(More)
Smog pollution is one of China’s most pressing public health issues today and has therefore received significant attention worldwide. Not only cities but also villages in China are suffering from smog pollution, especially since 2013. However, there is limited information available about public awareness on smog pollution in China, especially for where it(More)
The urban, constructed areas are full of buildings and different kinds of pavements and have a noticeable lack of trees and flora. These areas are accumulating the heat from the Sun, people, vehicles, and constructions. One interesting heat collector is the asphalt pavement. How does the heat transfer to different layers under the pavement or does it? What(More)
Ground source heat has been utilized for a heating and cooling several decades in Finland. The bottom of a water body is also another heat source used but no so commonly in Finland. The asphalt and seabed sediment heat sources are quite new approaches. In this paper these four different heat energy sources are reviewed, analyzed and compared. All these heat(More)
Asphalt fields like parking lots are found in urban environments. In the literature, they are indicated as one of the factors contributing to the urban heat island effect due to the ability of asphalt to absorb solar energy. Thermal profile data of these fields and their underground layers is, however, understudied and under-analyzed. In this paper,(More)
An understanding of behavior of a heat storage system provides possibility to design and build more optimal system. Improved optimal utilization of a seasonal heat storage system is possible with a better understanding the behavior of heat storage in a bedrock. For a small building or a house, heating or cooling demands can be met with efficient use of(More)
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