Loading...
5 results
Search Results
Now showing 1 - 5 of 5
- Assessment of mineral and organic compounds from livestock effluentsPublication . Oliveira, Verónica; Vitória, Cláudia; Monteiro, M.C.H.; Anjos, O.; Gallardo, EugeniaO processo eletrodialítico (ED) permite extrair macronutrientes (nitrogénio (N), fósforo (P), cálcio (Ca), potássio (K) e magnésio (Mg)) de efluentes pecuários, para obtenção de fertilizantes minerais de base biológica.
- Effects of struvite recovered from wastes in crop cultivationPublication . Oliveira, Verónica; Monteiro, M.C.H.; Rocha, J.L.; Ferreira, Célia D.Struvite recovered from wastes has been considered a promising second generation fertiliser. Themain objective of this work is to evaluate the effecls of struvite fertilisation on i) ryc (Secale cereale L.) cultivation (through a 45-d pot experiment), in terms of macronutrients, micronulrients and heavy metals and ii) on soil fertility (through a 30-d incubation experiment) in terms of available phosphorus and exchangeable bases (Ca2+, Mg2+ and K+). Struvite-fertilisation increased the soil available phosphorus resulting in improvement of the soil fertility class from low to medium class. In terms of exchangeable bases, the soil fertility class did not change. Furthermore, the struvite-fertilisation led to the highest concentration of total phosphorus in the plant. No relevant effects were found regarding the concentralions of Ca, Mg and K in the plant as well as the micronutrients. The leveis of heavy metals on crop did not increase after soiIs fertlisation with struvite.
- Evaluation of a phosphorus fertiliser produced from anaerobically digested organic fraction of municipal solid wastePublication . Oliveira, V.; Monteiro, M.C.H.; Ferreira, Celia D.When urban waste is not separately collected its phosphorus content cannot be recovered. The production of phosphorus-based fertilisers from urban waste could generate phosphorus added-value products, reduce environmental impacts from waste disposal and lower the consumption of virgin raw materials in the fertiliser industry. The main objective of this work was to evaluate the short-term agronomic value of a phosphorus fertiliser, which has the same chemical composition and mineralogical structure as struvite, but is artificially produced using phosphorus recovered from the anaerobically digested organic fraction of municipal solid waste (herein referred to as “secondary struvite”). To evaluate the release of phosphorus forms over time a 30 d incubation experiment was performed. Then the cultivation of rye (Secale cereale L.) was done in pot scale during 45 d to assess the phosphorus phytoavailability and the agronomic potential of secondary struvite, when compared with the commercial mineral fertiliser, single superphosphate. This work contributes to fill a knowledge gap about the effects of this secondary struvite as a source of phosphorus on soil phosphorus forms as well as on phosphorus’ soil and plant availability. At the end of the incubation experiment, a similar distribution of phosphorus forms in soil for both secondary struvite and single superphosphate was observed; however, the soil Olsen phosphorus was significantly higher in the soils fertilised using secondary struvite than in those fertilised by single superphosphate, which indicates that secondary struvite provided a higher amount of immediately phytoavailable phosphorus. The shoot biomass production (1.7 g dry-matter kg−1 soil) and the agronomic efficiency (66 g dry-matter g−1 phosphorus) were similar for both fertilisers. But the crop's phosphorus uptake and the apparent phosphorus recovery were higher (5.9 mg phosphorus kg−1 soil and 45%) in the secondary struvite treatment than in the single superphosphate treatment (4.7 mg phosphorus kg−1 soil and 36%). The results suggest that the secondary struvite can be used as a phosphorus fertiliser and lower rates of the secondary struvite are required to achieve the same agronomic efficiency as the single superphosphate.
- Improving the energy efficiency of an electrodialytic process to extract phosphorus from municipal solid waste digestate through different strategies.Publication . Oliveira, Verónica; Kirkelund, Gunvor M.; Monteiro, M.C.H.; Labrincha, João; Ferreira, Célia D.This work assesses the possibility of energy optimisation during the electrodialytic extraction of phosphorus from the municipal solid waste digestate. Strategies tested for energy optimisation consisted in (i) using a dualstage extraction approach; (ii) replacement of continuous stirring by pulse stirring and; (iii) utilisation of pulse electric current as an alternative to a constant current. Experiments were carried out using different stirring profiles (continuous stirring, pulsed stirring, manual stirring and no stirring) and different profiles for generating the electric field (continuous current and pulsed current). Dual-stage approach decreased the energy consumption by 30%. Energy was mainly used in the stirring operation (80%). Applying this strategy caused a faster acidification of the waste suspension and reduced the time required for the extraction. As for the second strategy, use of pulse stirring, it is possible to save energy by operating the stirrer 25% of the time, without compromising the phosphorus extraction values, which are close to 90%. Corresponding energy savings reached 70%. The third strategy tested, use of pulse current, had as side-effect a significant decrease of the phosphorus extracted, so the implementation of pulse current is not recommended. Overall, the energy efficiency of the electrodialytic extraction of phosphorus can be improved by 80% through the use of the dual-stage approach and the use of stirring for 25% of the time. There is also a potential in further reducing the energy use by further improving the stirring system.
- Avaliação do potencial fertilizante de resíduos orgânicos de agro-pecuária e de fertilizantePublication . Monteiro, M.C.H.; Oliveira, VerónicaAs matérias fertilizante provenientes das atividades agro-pecuária e agro-industrial, tais como estrumes, chorume, digestatos e compostos, avaliadas através de ensaios agronómicos referidos neste livro, mostraram (i) apresentar valor fertilizante, (ii) conduzir a uma economia de recursos naturais no que respeita aos nutrientes vegetais e (iii) contribuir (algumas) para um aumento do stock em carbono orgânico do solo, com vantagens para a saúde dos solos agrícolas ajudando também na mitigação das alterações climáticas por diminuição do teor em CO2 da atmosfera. Atualmente há cada vez mais um reconhecimento destes produtos não como resíduos, mas como recursos indispensáveis aos objetivos da economia verde no que respeita à implementação de práticas/tecnologias com zero de desperdício. Neste âmbito, também a produção de fertilizantes minerais de base biológica, obtidos através da extração de nutrientes vegetais a partir das referidas matérias fertilizantes, enquadradas aqui como fontes de nutrientes (matérias primas) mostrou ser uma tecnologia promissora, com resultados agronómicos semelhantes aos obtidos com os fertilizantes minerais tradicionais. Deste modo, a utilização destas práticas de fertilização permite fechar o ciclo antropogénico dos nutrientes em agricultura aproximando as atividades agrícola, pecuária, florestal e agro-industrial num ciclo de reutilização, recuperação e reciclagem com benefícios agronómicos e ambientais significativos.