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| 2. |
- Hamisi, Rajabu, et al.
(författare)
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Phosphorus sorption and leaching in sand filters used for onsite wastewater treatment - a column experiment
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Recension (refereegranskat)abstract
- The sorption capacities of filter sands used for onsite wastewater treatment and their associated risks of phosphorus (P) leakage on contact with rainwater were investigated in column experiments and modelling studies. Columns packed with sand were exposed to real domestic wastewater of different characteristics and hydraulic loading modes. The wastewater fed into the columns was effluent collected from three different treatment units in the field: a septic tank (ST), biofiltration tank (BF) and Polonite® filter bag (PO). The risk of P leaching to groundwater and surface water was also assessed, by exposing the same sand columns to artificial rainwater. The results indicated that sand columns can exhibit different adsorption capacities for Total-P, phosphate-P and total suspended solids, depending on the characteristics of influent wastewater. The adsorption capacity increased in the order ST > BF > PO, based on availability of organic matter to form biofilm. Effluent from Pol columns was significantly clearer, indicating lower organics content, than effluent from ST and BF columns. The modelled breakthrough curves for Total-P desorption agreed satisfactorily with the measured values, but further model improvement is needed.
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| 4. |
- Susilo, Yusak, 1976-
(författare)
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Bounded Rational Choice Behaviour
- 2017
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Ingår i: Journal of Transport Geography. - : ELSEVIER SCI LTD. - 0966-6923 .- 1873-1236. ; 62, s. 265-266
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Recension (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Halilovic, Armin E., et al.
(författare)
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A conceptual modeling approach for investigating multiple failure mechanisms in the environmentally driven ductile-to-brittle transition region
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- A continuum modeling approach that considers two separate failure mechanisms of steels subjected to hydrogen embrittlement is proposed based on experimental observations. The brittle failure is modeled using a cohesive zone approach, where both the cohesive strength and the fracture energy are degraded when exposed to hydrogen. The ductile failure is modeled using the Gurson model that includes a strain driven nucleation of void. Here, the nucleation model also incorporates hydrogen degradation where an increase in hydrogen is assumed to increase the volume of nucleated voids. This modeling approach is divided into two parts where the first step is to utilize a conceptual degradation of both failure modes and calibrate modeling parameters, and the second part incorporates a coupled diffusion-mechanical approach.
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| 9. |
- Halilovic, Armin E., et al.
(författare)
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An experimental fracture mechanics study of the combined effect of hydrogen embrittlement and loss of constraint
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Recension (övrigt vetenskapligt/konstnärligt)abstract
- This work presents a systematic investigation of the combined effect of hydrogen embrittlement and loss of constraint. The fracture mechanics experiments are performed on an advanced martensitic high strength steel using a single-edge-notch bend specimen, with different crack over height ratio, subjected to electrochemical in-situ hydrogen charging at various loading rates. It is found that the environmentally driven ductile-to-brittle transition region in fracture toughness is obtained for both the high and low constraint specimen configurations. This region is characterized by a change from transgranular dimple rupture to an intergranular mode of fracture. The transition region for the low constraint specimen is shifted towards longer hydrogen exposure times, which is an effect of the reduced hydrostatic stress ahead of the crack front compared to the high constraint specimen. The low constraint specimen exhibits significant plastic straining, which is reflected in a significant decrease in the fracture toughness due to hydrogen transgranular assisted dimple rupture.
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| 10. |
- Hamisi, Rajabu, et al.
(författare)
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Simulating the hydraulic dynamics and treatment performance of a sequencing batch flow constructed wetland
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Recension (refereegranskat)abstract
- In a six-month field trial, the performance of a full-scale sequencing batch flow constructed wetland (SBCW) treating on-site wastewater was determined. The filling and draining periods lasted 5-9 days, depending on wastewater production by users (two households). The results indicated that the SBCW system efficiently removed ammonium-nitrogen (NH4-N, 76%) and Escherichia coli (89%). However, draining by pumping increased preferential water flow and considerably limited removal of dissolved phosphorus (PO4-P) in the filter bed. Analysis of water samples from nine points and three vertical levels of the wetland bed showed that pumping aerated the bed, resulting in removal of NH4-N being highest in the top 0-0.2 m layer (43%) intermediate in the 0.2-0.4 m layer (32%), and lowest in the deep (0.4-0.6 m) layer (4%). Complementary modeling using COMSOL Multiphysics software to predict the hydraulic dynamics for three different SBCW designs indicated that the drainage system of the present SBCW should be re-designed to increase contact time and aeration, for improved phosphorus and nitrogen removal.
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