Uno Andersen

Avdelingsingeniør

(+47) 920 40 983
uno.andersen@nibio.no

Sted
Ås - Bygg F20

Besøksadresse
Fredrik A. Dahls vei 20, 1430 Ås

Sammendrag

Several species of microalgae and phototrophic bacteria are able to produce hydrogen under certain conditions. A range of different photobioreactor systems have been used by different research groups for lab-scale hydrogen production experiments, and some few attempts have been made to upscale the hydrogen production process. Even though a photobioreactor system for hydrogen production does require special construction properties (e.g., hydrogen tight, mixing by other means than bubbling with air), only very few attempts have been made to design photobioreactors specifically for the purpose of hydrogen production. We have constructed a flat panel photobioreactor system that can be used in two modes: either for the cultivation of phototrophic microorganisms (upright and bubbling) or for the production of hydrogen or other anaerobic products (mixing by “rocking motion”). Special emphasis has been taken to avoid any hydrogen leakages, both by means of constructional and material choices. The flat plate photobioreactor system is controlled by a custom-built control system that can log and control temperature, pH, and optical density and additionally log the amount of produced gas and dissolved oxygen concentration. This paper summarizes the status in the field of photobioreactors for hydrogen production and describes in detail the design and construction of a purpose-built flat panel photobioreactor system, optimized for hydrogen production in terms of structural functionality, durability, performance, and selection of materials. The motivations for the choices made during the design process and advantages/disadvantages of previous designs are discussed.

Sammendrag

The efficiency of different organic waste material as NPK fertilizer and risk for leaching losses related to shower precipitation in the first part of the growing season was testet in a pot experiment on a sandy soil in green house. Six organic fertilizers were evaluated: liquid anaerobic digestate (LAD) of source separated household waste, nitrified liquid anaerobic digestate (NLAD) of same origin as LAD, meat and bone meal (MBM), hydrolysed salmon protein (HSP), reactor composted catering waste (CW) and cattle manure (CM). Unfertilized control, calcium nitrate (CN) and compound fertilizer, Fullgjødsel® 21-4-10 were used as reference fertilizers. Two levels of N-fertilization were applied: 80 kg N ha-1 and 160 kg N ha-1. The amount of fertilizer applied was based on content of mineral N for LAD, NLAD, CN and Fullgjødsel, while Kjeldahl-N content was used for dosage of MBM, HSP, CW and CM. At Zadoks 14 the pots were given a surplus of 28 mm water, as a simulated shower precipitation, and leached water was collected and analyzed for content of N and P. LAD and Fullgjødsel® gave equal yield of barley and uptake of N, P, and K in barley grain, when equal amounts of mineral nitrogen were applied. NLAD gave significantly lower barley yield than the original LAD due to leaching of nitrate-N after simulated surplus of 28 mm precipitation at Zadoks 14. CW also gave yield of barley grain similar to Fullgjødsel®, but significantly less yield of straw. The nutrient content in the different organic fertilizers caused different yield limiting effects. MBM showed K deficiency and had equally small K uptake as CN. Cattle manure had only a small portion of mineral N, and low uptake of N. NLAD had low uptake of P compared to LAD, which also was related to smaller amount of P applied in NLAD. The was significant increased leaching of nitrate N from the treatments receiving 160 kg N ha-1 of CN and NLAD compared to all the other organic fertilizers. It was found significant increased leaching of NH4-N at LAD with 160 kg N ha-1 compared to the other treatments, but the amount of leached NH4-N was very small compared to the nitrate-N leaching for the CN and NLAD treatments. Although the LAD treatment received less P than the CM treatment, the highest P-leaching was found for the LAD treatment. A relatively high proportion of the leached P was PO4-P for the LAD treatment receiving 160 kg N ha-1. CM and CW also had significantly higher P leaching than the other organic fertilizers at 160 kg N ha-1, while most of the treatments had very small P losses and not significantly higher than the unfertilized control. This study showed that liquid anaerobic digestate (LAD) was equally good as NPK fertilizer to barley when equal amounts of mineral N were applied. Liquid anaerobic digestate made of source separated household waste can be recommended as fertilizer to cereals. Nitrification of the ammonium N in the digestate caused significantly increased nitrate leaching, and can not be recommended. The composted catering (CW) and hydrolysed salmon protein (HSP) also showed good fertilizer effect, but these fertilizers had not optimal NPK composition and had lower K content than the crop demand. In these materials are used as fertilizers additional K should be applied in order to obtain normal yields.