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Oslo, Norway

Akerstrom A.M.,Norwegian University of Life Sciences | Mortensen L.M.,Norwegian University of Life Sciences | Rusten B.,Aquateam COWI AS | Gislerod H.R.,Norwegian University of Life Sciences
Journal of Environmental Management | Year: 2014

The use of microalgae for biomass production and nutrient removal from the reject water produced in the dewatering process of anaerobically digested sludge, sludge liquor, was investigated. The sludge liquor was characterized by a high content of total suspended solids (1590mgL-1), a high nitrogen concentration (1210mgL-1), and a low phosphorus concentration (28mgL-1). Chlorella sp. was grown in sludge liquor diluted with wastewater treatment plant effluent water to different concentrations (12, 25, 40, 50, 70, and 100%) using batch mode. The environmental conditions were 25°C, a continuous lightning of 115μmolm-2s-1, and a CO2 concentration of 3.0%. The highest biomass production (0.42-0.45gdryweightL-1Day-1) was achieved at 40-50% sludge liquor, which was comparable to the production of the control culture grown with an artificial fertilizer. The biomass production was 0.12 and 0.26gdryweightL-1Day-1 at 12% and 100% sludge liquor, respectively. The percentage of nitrogen in the algal biomass increased from 3.6% in 12% sludge liquor and reached a saturation of ~10% in concentrations with 50% sludge liquor and higher. The phosphorus content in the biomass increased linearly from 0.2 to 1.5% with increasing sludge liquor concentrations. The highest nitrogen removal rates by algal biosynthesis were 33.6-42.6mgTNL-1Day-1 at 40-70% sludge liquor, while the highest phosphorus removal rates were 3.1-4.1mgTPL-1Day-1 at 50-100% sludge liquor. © 2014 .

Dereszewska A.,Maritime Academy of Gdynia | Cytawa S.,Swarzewo Wastewater Treatment Plant | Tomczak-Wandzel R.,Aquateam COWI AS | Medrzycka K.,Technical University of Gdansk
Polish Journal of Environmental Studies | Year: 2015

This paper discusses the influence of a wide range of anionic surfactant concentrations on activated sludge. Linear alkylbenzene sulphonate (LAS) was chosen as an example of a commonly used anionic surfactant. The fate of the surfactant during biological treatment of wastewater was tested. The effect of surfactant on glucose and starch removal was studied. It has been found that in the case of glucose the removal was independent of LAS concentration, while in the case of starch it was incomplete at high surfactant loads (above 15 mg·(g·dss)-1). The study established that surfactants can activate or inhibit microorganism activity, depending on surfactant concentration. LAS loads up to 3 mg·(g·dss)-1 positively stimulate the removal of COD, phosphorus release and the respirometric activity of the sludge. LAS loads higher than 15 mg·(g·dss)-1 inhibit respiration of activated sludge bacteria and decrease phosphorus removal. It also affects the morphology of activated sludge flocs, causing their fragmentation and lysis of protozoa cells. © 2015, HARD Publishing Company. All rights reserved.

Xin G.,Aquateam COWI AS | Lopes M.P.,New University of Lisbon | Crespo J.G.,New University of Lisbon | Rusten B.,Aquateam COWI AS
Separation and Purification Technology | Year: 2013

In the rubber parts industry, the treatment of wastewater from the demolding process utilising polymeric agents, traditionally poses a challenge. This is due to the high strength (COD > 10,000 mg/L) and the low biodegradability of the main organic content in the wastewater. Typically, a thermal process of boilers followed by evaporators is commonly employed to treat the wastewater. Besides frequent boiler maintenance due to severe fouling caused by the nature of the wastewater, high energy costs are nearly prohibitive. At Cikautxo, a Spanish rubber parts manufacturer, the energy costs are in the region of €4.2/m3 treated wastewater. Following an initial lab scale membrane screening, a pilot study was carried out at Cikautxo in 2012. Nanofiltration using a NF270 membrane was tested and the reject stream was collected and used to feed a full size evaporator. Without pretreatment, the rate of the nanofiltration process was maintained at a permeate flux of 11 L/m2-h for periods of over 30 h in between flux recovery cleaning. The use of the NF process gave a significantly improved feed water quality, consequently improving the total capacity of the evaporator when compared with the use of the boiler blow down method. The NF + evaporator solution was shown to effectively reduce energy costs by 55% (from €4.2/m3 to €1.9/m3 treated wastewater). © 2013 Elsevier Ltd. All rights reserved.

Razafimanantsoa V.A.,University of Stavanger | Ydstebo L.,University of Stavanger | Bilstad T.,University of Stavanger | Sahu A.K.,University of Stavanger | And 2 more authors.
Water Science and Technology | Year: 2014

The purpose of this project was to investigate the effect of selective particle removal during primary treatment on downstream biological nutrient removal processes. Bench-scale Salsnes Filter fine mesh sieves were used as a primary treatment to obtain different organic fractions to test the effect on denitrification. Activated sludge and moving bed biofilm reactor anoxic tests were performed on municipal wastewater collected from two full-scale wastewater treatment plants located around the Oslo region (Norway). About 43% of the suspended solids in the wastewater was less than 18 μm, and 14% was between 18 and 150 μm. The effect of particulate chemical oxygen demand (COD) removal on denitrification rates was very minor. © IWA Publishing 2014.

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