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Advancing performance of green technologies for remediation and reclamation of degraded urban soils
(2015)
Progressing degradation of agricultural soil demands a change to more sustainable cropping systems accounting for crops that can sustain the soil health. Hemp is known for the improvement of soil physical, chemical and biological properties. The objective of the research is to analyze the hemp plant capability to grow under nutrient poor soil conditions and dense canopy and to assess hemp’s ability to uptake plant nutrients applied with/by soil amendments produced from biowaste. Additionally, the research aims to analyze how the hemp nutrition affects its morphogenesis, thus the fiber content.
In the greenhouse set up, Cannabis Sativa L. was grown in sandy substrate, with limited water supply that corresponded to the common drought periods in Brandenburg (Germany) and with addition of soil amendments in form of pellets from organic waste (OW) digestives. The treatments included: 5 control pots, 10 pots with pellets (19 kg soil / 230 g pellets according to the allowed application of 13 t/ha) and 10 pots with 19 kg soil / 3 kg pellets. When needed, a universal liquid fertilizer was applied which contained water soluble minerals like N, P2O5 and K2O. After 92 days, the plants were harvested, dried and weighted. The root structure was examined visually. The stems were decorticated using BMS-FLAKSY® (Rossmanith GmbH) to analyze the fiber content. The Elementar vario MAX cube analyzer device was used to analyse C and N contents.
The results showed that hemp could still flourish in water and nutrient limited environment. A deeper and denser rooting was observed in the treatments with pellets. It was observed that fine roots were encircled and attached to the pellets to access the nutrients stored there. The highest C:N ratio in soil and in leaves was found in treatments that contained the most pellets. The option to apply pellets produced from OW in larger quantities instead of a fertilizer application had a striking effect on hemp growth and biomass accumulation hence, increased dry matter amount and fiber yield.
Detection and behavior of iron-cyanide complexes in soils of a former Manufactured Gas Plant site
(2014)
In Germany, soil and groundwater atmore than a thousand sites are contaminatedwith ironcyanide complexes. These contaminations originate from the gas purification p process that was conducted inManufactured Gas Plants (MGP).There is a risk of human threat depending on the stability dissolved iron-cyanide complexes due to the potential release of toxic free cyanide, CN(aq) and HCN(g), (aq). The aim of this thesis was to evaluate a new method for the cyanide detection and to investigate the stability and retardation of the iron-cyanide complexes in soils by batch and column experiments in order to improve the knowledge concerning the fate of cyanide compounds in soil and groundwater. This study seeks for enhancing the efficiency of phytoremediation as a proper approach to decontaminate ironcyanides complexes and thus tries to make a contribution to environmental protection.
Soils and groundwater on sites of the former Manufactured Gas Plants (MGPs) are contaminated with various complex iron-cyanides (Fe-CN). Phytoremediation is a promising tool in stabilization and remediation of Fe-CN affected soils, however, it can be a challenging task due to extreme adverse and toxic conditions. Phytoremediation may be enhanced via rhizosphere microbial activity, which can cooperate on the degradation, transformation and uptake of the contaminants. Recently, increasing number of scientist reports improved plants performance in the removal of toxic compounds with the support of arbuscular mycorrhizae fungi (AMF). Series of batch experiments using potassium hexacyanoferrate (II) solutions, in varying concentrations, were used to study the effect of ryegrass roots (Lolium perenne L.) inoculation with Rhizophagus irregularis and a mixture of Rhizophagus irregularis, Funneliformis mosseae, Rhizophagus aggregatus, and Claroideoglomus etunicatum on Fe-CN sorption. Results indicated significantly higher colonization of R. irregularis than for the mixture of AMF species on ryegrass roots. Sorption experiments revealed significantly higher reduction of total CN and
free CN content in the mycorrhizal roots, indicating greater cyanide decrease in the treatment inoculated with R. irregularis. Our study indicates contribution of AM fungi in phytoremediation of Fe-CN contaminated soil.
With recent policy developments, an increase in organic waste utilization is expected. However, the use of organic amendments to reduce the mobility of iron‐cyanide (Fe‐CN) complexes and simultaneously promote vegetation growth has not been studied before. Therefore, we evaluated the effect of (a) drying, (b) composting, and (c) pelletizing on the ability of digestates (biowastes from an anaerobic treatment of municipal organic waste) to provide easily available nutrients and stabilize Fe‐CN complexes.
Extraction with deionized water resulted in a considerably higher nutrient and carbon elution from air‐dried and oven‐dried digestates (50% dry matter [DM] of total K, 11% DM Mg, 7% DM Ca, and 6% DM C). Mixer‐pelletized digestates stand out among the composted samples (42% of total K, 3% DM C, 5% DM P, 1.5% DM Mg, and 1% DM Ca). The adsorption experiment showed the highest significant tot. CN conc. reduction using noncomposted, air‐dried (100%), and oven‐dried (82%) digestates. Significant correlations have been found for Mg, Ca, and dissolved organic carbon elution and slightly acidic pH as well as CN adsorption. The Fourier transform infrared analysis revealed Fe‐CN complexation on inorganic (K₂Mn[Feᴵᴵ(CN)₆] and NH₄Fe[Feᴵᴵ(CN)₆]) and organic constituents indicating formation of nitriles. Air‐ and oven‐dried digestates showed the most promising results in terms of nutrients' availability and ability to decrease Fe‐CN complex mobility.