Feasibility of the use of recycled nutrients in fast growing pulpwood production

The application of pulp and paper mill (PPM) sludge in agriculture and forestry has been acknowledged as soil amendments and a plant nutrient source. The main objectives of this study were to evaluate the total cost of the use of recycled nutrients from PPM sludge in fast growing pulpwood production, and the financial profitability of fast growing pulpwood production with the use of these recycled nutrients. The investment and production costs of fast growing pulpwood plantation were directly acquired from a previous research, while the other data was compiled through different studies. The total cost of the use of PPM sludge was evaluated based on assumed factors. Discounted cash flow method was used to evaluate the financial profitability, using NPV and IRR as indicators. The results of estimated sludge nutrient contents were 16.2 g N, 2.9 g P, and 2.4 g K kg-1 of dry sludge. The sludge application rate was estimated at 1.36 Mg/ha in the first year. The total cost of the use of PPM sludge involved transport and spreading cost of US$49.15/dry ton. The fertilization cost applied in the financial model was designed in 3 different options and their results were as follows: option (1) was taken directly from the reference research (US$97/ha); option (2) was the use of sludge alone (US$66.75/ha); and option (3) was the use of sludge and TSP fertilizer (US$83.80/ha). The average NPV without discounting was US$248,180 while the IRRs ranged between approximately 3-4% with an average of 3.63%. Although option (2) and (3) contributed to higher IRRs compared to option (1), this increase was still not significant as the IRR was not sensitive to the total fertilization cost. The advantages are that this practice can be performed at a lower cost and the application rate can be still increased if necessary. It is better for forest plantations compared to agriculture and consequently supports reforestation program. In addition, it can be similarly applied in wood biomass production. A disadvantage is that the IRRs were not very favorable compared to the criterion of 11%. The sludge high in C:N ratio can cause nitrogen immobilization, and regulatory concerns may restrict and complicate the use of sludge landspreading and contribute to additional costs and processes.

Intensification of Operation of Inclined Plate Settler at Fertilizer Plant

Fertilizer plant’s process waters contain high concentrations of nitrogen compounds, such as ammonium and nitrate. Phosphorus and fluorine, which originate from phosphoric acid and rock phosphate (apatite) used in fertilizer production, are also present. Phosphorus and nitrogen are the primary nutrients causing eutrophication of surface waters. At fertilizer plant process waters are held in closed internal circulation. In a scrubber system process waters are used for washing exhaust gases from fertilizer reactors and dry gases from granulation drums as well as for cooling down the fertilizer slurry in neutralization reactor. Solids in process waters are separated in an inclined plate settler by gravitational sedimentation. However, the operation of inclined plate settler has been inadequate. The aim of this thesis was to intensify the operation of inclined plate settler and thus the solids separation e.g. through coagulation and/or flocculation process. Chemical precipitation was studied to reduce the amount of dissolved species in process waters. Specific interest was in precipitation of nitrogen, phosphorus, and fluorine containing specimens. Amounts of phosphorus and fluorine were reduced significantly by chemical precipitation. When compared to earlier studies, annual chemical costs were almost eight times lower. Instead, nitrogen compounds are readily dissolved in water, thus being difficult to remove by precipitation. Possible alternative techniques for nitrogen removal are adsorption, ion exchange, and reverse osmosis. Settling velocities of pH adjusted and flocculated process waters were sufficient for the operation of inclined plate settler. Design principles of inclined plate settler are also presented. In continuation studies, flow conditions in inclined plate settler should be modelled with computational fluid dynamics and suitability of adsorbents, ion exchange resins, and membranes should be studied in laboratory scale tests.

The transfer of 137Cs through the soil-plant-sheep food chain in different pasture ecosystems

Selostus: Radiocesiumin kulkeutuminen eri laidunekosysteemien maa-ruoho-lammas -ravintoketjussa

Supply of nutrients and productive responses in dairy cows given diets based on restrictively fermented silage

Selostus: Ravintoaineiden saantiin ja maidontuotantoon vaikuttavat tekijät runsaalla säilörehuruokinnalla

The leaching of nutrients from ash- and PK-fertilised peat

Tiivistelmä: ravinteiden huuhtoutuminen tuhka- ja PK-lannoitetusta turpeesta

Yields, plant characteristics, total N and fibre composition of timothy cultivars grown at two latitudes

Selostus: Timoteilajikkeiden sadot, kasvuominaisuudet sekä typpi- ja kuitupitoisuus kahdella leveysasteella

Plant adaptation to temperature and photoperiod

Selostus: Kasvien sopeutuminen lämpötilaan ja päivän pituuteen

The effect of regular collection of Drosera rotundifolia in natural peatlands in Finland: plant density, yield and regeneration

Tiivistelmä

Responses of yield and N use of spring sown crops to N fertilization, with special reference to the use of plant growth regulators

Selostus: Typpilannoituksen ja kasvunsääteiden vaikutukset kevätviljojen ja rypsin satoon sekä typen käyttöön