Effects of organic matter components and incubation on the cement-based stabilization/solidification characteristics of lead-contaminated soil

Microencapsulation of zinc plating waste using silicone polymers

This paper deals with the treatment of hazardous zinc-bearing waste using hydraulic binders and silicone polymers, with the aim to allow its safe disposal into landfill. The waste was solidified using hydraulic binders in the first step and then encapsulated using silicone polymers. Samples were characterised using x-ray fluorescence, x-ray diffraction, and scanning electron microscopy. The effectiveness of the process was evaluated by leaching tests in distilled water and in an acidic environment according to Toxicity Characteristic Leaching Procedure. The effect of porosity and pH on the release of pollutants was also studied. Zinc and chloride were identified as the most significant pollutants in the waste. Portland cement did not stabilize them efficiently. The two-step treatment with Portland cement and silicone binders decreased, in the best case, the concentration of zinc and chloride in acidic extracts from 12,400 mg/L and 38,300 mg/L to 21.9 mg/L and 74 mg/L, respectively, and the treated waste complied with regulatory requirements for hazardous waste disposal into landfills. The two-step treatment was also found as a more effective method than microencapsulation using a silicone binder alone. The factor that most affects leachability appears to be the porosity of the encapsulated waste.

Hazardous elements in the soil of urban cemeteries; constructive solutions aimed at sustainability

Urban cemeteries on a global scale raise concerns due to their potential to concentrate differing levels of hazardous pollutants in their native soils due to the unnatural concentration of burials in a limited space. It is paramount for sustainability that designers of future cemeteries take this into account in order to minimize the deposition and movement of these contaminants within the soil profile. The objective of this manuscript is to identify the levels of certain hazardous element contamination, specifically heavy metals, in the soil of horizontal urban cemeteries that do not utilize herbicides for weed control. In this, solutions were sought for the construction of future urban cemeteries capable of mitigating further contamination of the environment by the increase in interments. The soils of three urban cemeteries (A, B and C) in the Brazilian city of Carazinho, in Rio Grande do Sul State, were sampled with 5 monitoring points in the internal area and 5 points in the external area of the cemeteries. At each point, 3 replications were performed at two depths (0-20 and 20-40 cm), totaling 180 samples in all, to determine the concentration of the following metals: copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), lead (Pb), and chromium (Cr) (g kg^-1). In addition, online interviews with 15 architects who design cemeteries were conducted. Architectural design solutions to mitigate environmental contamination were modeled utilizing the Building Information Modeling system (BIM). The results showed an excess of Cu in the soil of cemeteries A, B and C, surpassing the standards allowed by Brazilian federal regulations. A total of 80% of the interviewed architects expressed their preference for the vertical cemetery, with gas and effluent treatment systems to mitigate environmental impacts.