Biomedical subjects

Petter D Jenssen

Publications and source records attributed to Petter D Jenssen.

3 recordsLinked to original sources

PubMed2005

Phosphorous sorption by Filtralite P--small scale box experiment.

Phosphorus (P) sorption of light weight aggregate, Filtralite P has been examined through a box experiment which imitates a horizontal subsurface flow wetland system. The results showed that after the P breakthrough, the outlet P concentration increased with time according to the amount of P applied. Small scale boxes with a high inlet P concentration (15 ppm) and high loading rate (5-2.5 L d(-1)) reached 90% saturation level relatively quickly (after about 150 days of operation), while the boxes with low hydraulic loading rate (1.25 L day(-1)) were 70-90% saturated after 18 months of operation. The total P removal was dependent on pH, Ca, and the inlet P concentrations, but was independent of the hydraulic loading rate. Extraction of total P from the saturated filter material showed that the sorbed P accumulated within the inlet section of the box and decreased gradually towards the outlet as well as towards the bottom layer. Even after large amounts of Ca had leached out of the system, Filtralite P still had a very high P removal capacity. After resting periods the P sorption capacity of the material was regenerated, the P concentration in the effluent decreased by 22-53%.

Adsorption↗

PubMed2005

High performance constructed wetlands for cold climates.

In 1991, the first subsurface flow constructed wetland for treatment of domestic wastewater was built in Norway. Today, this method is rapidly becoming a popular method for wastewater treatment in rural Norway. This is due to excellent performance even during winter and low maintenance. The systems can be constructed regardless of site conditions. The Norwegian concept for small constructed wetlands is based on the use of a septic tank followed by an aerobic vertical down-flow biofilter succeeded by a subsurface horizontal-flow constructed wetland. The aerobic biofilter, prior to the subsurface flow stage, is essential to remove BOD and achieve nitrification in a climate where the plants are dormant during the cold season. When designed according to present guidelines a consistent P-removal of > 90% can be expected for 15 years using natural iron or calcium rich sand or a new manufactured lightweight aggregate with P-sorption capacities, which exceeds most natural media. When the media is saturated with P it can be used as soil conditioner and P-fertilizer. Nitrogen removal in the range of 40-60% is achieved. Removal of indicator bacteria is high and < 1000 thermotolerant coliforms/100 ml is normally achieved.

Biodegradation, Environmental↗

PubMed2005

Salinity effect on the characteristics of saturated horizontal flow in small boxes containing Filtralite-P.

Constructed wetlands are ecological systems that have proven their efficiency in treating wastewater and reducing pollutants of concern in both warm and cold climate. Oversizing these systems is common in the design process due to the inadequate knowledge about water movement in the porous media used. This study investigates the saturated horizontal flow pattern in a lightweight aggregates especially made for use in constructed wetlands termed Filtralite P using computer tomography and a chloride tracer under different hydraulic loading rates and inlet concentrations in a laboratory box experiment. The salt concentrations showed a major effect on the retention time and the flow by enhancing short-circuiting, preferential flow pattern. A hydraulic loading rate of 25 cm day(-1) is suggested as the safest loading rate with Filtralite P under different ranges of wastewater concentrations with a possibility to use a loading rate of 50 cm day(-1) only with municipal wastewater and not the industrial wastewater. The computer tomography images indicated that flow was going first to the bottom and then fluidise upward with a sharp boundary between the incoming and ambient water.

Ecosystem↗