Phytoremediation for heavy metal‐contaminated soils combined with bioenergy production

In June 2007, a project started in Flanders (Belgium) in which we will apply phytoremediation to clean soils that are diffusely polluted with heavy metals. Uptake ranges of heavy metals by rape seed, maize and wheat will be enhanced by increasing the bioavailability of these heavy metals by the addition of biodegradable physico‐chemical agents and by stimulating the heavy‐metal uptake capacity of the microbial community in and around the plant. In addition, the harvested biomass crops will be converted into bioenergy by using different energy‐recovery‐techniques. The energy and heavy metal mass balances will be compared for four different energy‐recovery techniques (anaerobic digestion, incineration, gasification and production of biodiesel). The overall information obtained will result in an economic evaluation of the use of phytoremediation combined with bioenergy production for the remediation of sites which are diffusely polluted with heavy metals. In the present review we will first explain the most important research steps investigated in our phytoremediation project. Secondly, an overview of literature discussing the phytoremediation capacity of rape seed to clean soils that are contaminated with heavy metals and the possibilities to produce biodiesel from this (heavy metal polluted) rape seed will be discussed in more detail. Fitoremediacijos taikymas sunkiaisiais metalais užterštame dirvožemyje derinant su bioenergijos gamyba Santrauka. 2007 m. birželį Flandrijoje (Belgija) pradėtas vykdyti projektas, kuriame mes pritaikysime fitoremediaciją siekdami išvalyti sunkiuosius metalus iš dirvožemio. Sunkiųjų metalų patekimas į rapsus, kukurūzus ir kviečius bus suintensyvintas didinant šių sunkiųjų metalų biopriimamumą dėl pridedamų biodegraduojančių fizikinių-cheminių priedų bei stimuliuojant mikrobiologinių bendrijų pajėgumą augale ir aplink jį sugerti sunkiuosius metalus. Be to, nuimta javų biomasė bus perdirbta į bioenergiją, taikant įvairias energijos gavybos technologijas. Energijos ir sunkiųjų metalų masės balansas bus palygintas pagal keturias skirtingas energijos gavybos technologijas (anaerobinis kompostavimas, deginimas, dujofikavimas ir biodyzelio gamyba). Visa gauta informacija leis ekonominiu požiūriu įvertinti fitoremediacijos, derinamos su bioenergijos gamyba, taikymą valant sunkiaisiais metalais nevienodai užterštus plotus. Pateikiamoje apžvalgoje pirma aptarsime svarbiausius fitoremediacijos projekto etapus. Antra, detaliau apžvelgsime literatūrą apie rapsų pajėgumą išvalyti dirvožemį, užterštą sunkiaisiais metalais, ir galimybes gaminti biodyzelį iš (sunkiaisiais metalais užterštų) rapsų sėklų. Reikšminiai žodžiai: fitoremediacija, sunkieji metalai, biomasė, energijos gamyba, rapsai, biodyzelis. Применение фиторемедиации в почве, загрязненной тяжелыми металлами и приспосабливаемой для производства биоэнергии Резюме. В июне 2007 г. во Фландере (Бельгия) была начата работа над проектом по фиторемедиации с целью очищения почвы от тяжелых металлов. Процесс поглощения тяжелых металлов рапсом, кукурузой и пшеницей будет более интенсивным благодаря введению биодеградирующих физико-химических добавок и стимуляции способности микробиологических сообществ в растении и вокруг него впитывать тяжелые металлы. Снятая биомасса зерновых с помощью различных технологий по производству энергии будет конвертирована в биоэнергию. Баланс энергии и массы тяжелых металлов будет сравнен с помощью четырех разных технологий по производству энергии (анаэробического компостирования, сжигания, газофикации, производства биотоплива). Полученная информация позволит с экономической точки зрения оценить применение фиторемедиации как для очищения площадей, в разной степени загрязненных тяжелыми металлами, так и для производства биоэнергии. В статье прежде всего проанализированы важнейшие этапы проекта по фиторемедиации. Затем произведен обзор литературы о способности рапса благодаря фиторемедиации очищать почву, загрязненную тяжелыми металлами, и возможностях производства биотоплива из семян рапса, загрязненных тяжелыми металлами. Ключевые слова: фиторемедиация, тяжелые металлы, биомасса, производство энергии, семена рапса, биотопливо. First Published Online: 14 Oct 201

Progress in assisted natural remediation of an arsenic contaminated agricultural soil

A contaminated soil was collected in a field adjacent to a derelict As (III) smelter in Reppel (Bocholt, Belgium). A single soil treatment (% by soil weight) based on either iron grit (SS, 1%), beringite (B, 5%), or iron grit (1%) + beringite (5%) (BSS) was applied. Untreated and treated Reppel soils and a control soil were placed in lysimeters inside a greenhouse and cropped annually. The efficiency of soil treatments in decreasing As and metals in exposure sources and restoring soil functions was assessed 6 years after the treatments commenced. Decreases in extractable Cd, Mn, Zn and As occurred in the BSS soil. Only BSS treatment reduced both As and metal concentrations in leachates. BSS treatment produced best growth of lettuce and cabbage, the highest shoot and pod yields for dwarf bean, the lowest As, Cd and Zn concentrations in plant tissues, and partly restored Rhizobium nodulation on bean roots. The epigeic earthworm (Dendrobaena octaedra) could only survive in the BSS soil. Depurated living worms from the BSS soil had Cd concentration similar to those in control worms, but higher As, Ca, Fe, and Zn concentrations. Based on physiologically based extraction test (PBET), As bioaccessibility was reduced from 12% (untreated soil) to 7.4% (BSS) and 3% (SS), but only the SS treatment decreased the bioaccessibility of Cd (-30%) and Pb (-35%). The range of chemical and biological indicators suggested that BSS amendment was the most effective treatment for restoration of normal soil functions 6 years after initial treatment of the Reppel soi

An in vitro investigation of species-dependent intestinal transport of selenium and the impact of this process on selenium bioavailability.

A range of Se species has been shown to occur in a variety of different foodstuffs. Depending on its speciation, Se is more or less bioavailable to human subjects. In the present study, the role of speciation as a determinant of Se bioavailability was addressed with an investigation of species-specific mechanisms of transport at the intestinal level. The present work focused on four distinct Se compounds (selenate (Se(VI)), selenite (Se(IV)), selenomethionine (SeMet) and methylselenocysteine (MeSeCys)), whose intestinal transport was mimicked through an in vitro bicameral model of enterocyte-like differentiated Caco-2 cells. Efficiency of Se absorption was shown to be species dependent (SeMet>MeSeCys>Se(VI)>Se(IV)). In the case of SeMet, MeSeCys and Se(VI), the highly polarised passage from the apical to basolateral pole indicated that a substantial fraction of transport was transcellular, whilst results for Se(IV) indicated paracellular diffusion. Passage of the organic Se species (SeMet and MeSeCys) became saturated after 3 h, but no such effect was observed for the inorganic species. In addition, SeMet and MeSeCys transport was significantly inhibited by their respective S analogues methionine and methylcysteine, which suggests a common transport system for both kinds of compounds