Experience of using sewage sludge in soil for green building

Wastewater sludge from municipal wastewater treatment plants in Nizhny Novgorod and soils based on them, prepared with different ratios of sludge, sawdust and peat, have been investigated. Sewage sludge-based soils contain plant nutrients and are suitable for use as fertilizing materials in green building. Under the conditions of a three-year lysimetric experiment on cereal lawn grasses, a significant efficiency of organic soils was noted in comparison with traditional soils. The lawn maintenance regime revealed differences in the mixtures of fertilizing materials in terms of the effect on the productivity of the phytocenosis. Use of sewage sludge containing large amounts of heavy metals as one of the soil components undoubtedly leads to increase in the amount of these toxic elements in the soil as a whole.

Sorption of Polycyclic Musks on Soil Components of Different Aggregate Sizes: The Effect of Organic-mineral Interactions

Polycyclic musks (PCMs) in soil environments have been of increasing concern because of their potential characteristic of persistence, bioaccumulation, and potential ecological risk. However, little is known about their fate process in soil environments. Here, we selected two PCMs as sorbates, namely galaxolide (HHCB) and tonalite (AHTN), to explore their sorption process in soils. Sorption batch experiments with six nature soils and their different aggregate fractions were carried out to elucidate the effect of organic–mineral interactions in different aggregate sizes on sorption of these two PCMs. The possible causes of variation in the organic carbon-normalized partition coefficient (Koc) for HHCB and AHTN have been investigated. The results indicated that the sorption contribution to different aggregate fractions to the overall sorption was dependent on both Koc and content of each aggregate fraction. The strong influence of organic–mineral interactions on Koc was evidenced by the large variation in Koc on HF-treatment for both bulk soils and their different aggregate fractions. This study verified the dual effect of organic–mineral interactions among selected soils. By comparing the measured and theoretical overlay ∆ Koc values, it was indicated that the interaction between particles of different size fractions will also affect Koc variation. This study represents a valuable contribution to the understanding of the fate processes and behaviors of PCMs in soil and its implication on the risk assessment.

Mechanisms of Tebuconazole Adsorption in Profiles of Mineral Soils

The study attempted to identify the soil components and the principal adsorption mechanisms that bind tebuconazole in mineral soils. The KF values of the Freundlich isotherm determined in 18 soils from six soil profiles in batch experiments after 96 h of shaking ranged from 1.11 to 16.85 μg1–1/n (mL)1/n g–1, and the exponent 1/n values from 0.74 to 1.04. The adsorption of tebuconazole was inversely correlated with the soil pH. Both neutral and protonated forms of this organic base were adsorbed mainly on the fraction of humins. The adsorption of the protonated form increased in the presence of hydrogen cations adsorbed in the soil sorption sites. Fourier transform infrared spectroscopy coupled with the molecular modeling studies and partial least squares regression analysis indicated that the tebuconazole molecule is bound in the organic matter through the formation of hydrogen bonds as well as hydrophobic and π–π interactions. Ion exchange was one of the adsorption mechanisms of the protonated form of this fungicide. The created mathematical model, assuming that both forms of tebuconazole are adsorbed on the organic matter and adsorption of the protonated form is affected by the potential acidity, described its adsorption in soils well.