Elżbieta Sobiecka

Influence of mixture ratio and pH to solidification/stabilization process of hospital solid waste incineration ash in Portland cement

Solidification/stabilization (S/S) is an established utilization technology to treat hazardous wastes. This research explored the influence of pH (3-12) on the immobilization of heavy metals present in five mixtures of hospital solid waste incinerator ash and Portland cement, following two different processes of waste solidification/stabilization (cement hydration and granulation). In general, cement hydration process resulted in more stable products than granulation process. A high ash content in the mixture with Portland cement (60wt%) resulted in the highest immobilization of Pb(2+) and Cu(2+), while a low ash content in the mixture (10wt%) resulted in the lowest leachability of Zn(2+). When ash and Portland cement was mixed in equal proportions (50wt%) the highest encapsulation was observed for Ni(2+), Cd(2+) and Cr(3+). Neutral and weak alkaline pH values within the range pH=7-8 resulted in the lowest leachability of the monitored heavy metals.

Lindane, kepone and pentachlorobenzene: chloropesticides banned by Stockholm convention

Persistent organic pollutants are a serious problem to the environment due to their toxicity to both fauna and flora. Extremely resistant to biodegradation and prone to transfer through long distances via atmosphere can contaminate almost any place in the planet. They tend to bioaccumulate in fat tissue due to their lipophilicity and seriously affect poisoned organism’s nervous, hepatic, reproductive or hormonal system. Since 2009, due to the Stockholm convention on persistent organic pollutants production and utilisation of certain halogenated pesticides has been prohibited. This group includes hexachlorocyclohexane, chlordecone (kepone) and pentachlorobenzene. All of these chloropesticides pose a serious threat to environment, and careful control of their production and release to the environment is required. This paper is a review of physical and chemical properties as well as sources in environment, impact on animal organisms, methods of degradation of most broadly used chlorinated persistent organic pollutants and suggestions concerning their utilisation.

INVESTIGATING THE CHEMICAL STABILIZATION OF HAZARDOUS WASTE MATERIAL (FLY ASH) ENCAPSULATED IN PORTLAND CEMENT

Portland cement has been suggested as an effective stabilization (physico-chemical) method for hazardous waste. This research explored the immobilization of metals in various mixtures of Portland cement and fly ash waste sampled from coal power plant in the province of Lodz, central Poland. The stabilization of fly ash in Portland cement was investigated under a wide range of pH conditions (3–12). Leachability tests were used to determine the efficiency of the encapsulation by studying the dissolution of alkaline metals (sodium, potassium) and alkaline earth metals (calcium, magnesium). The lowest value of leached metals was obtained for ratio of ash to cement of 1:10 in a case of sodium and calcium, while ratio 1.5 gave the lowest leached effects for potassium and magnesium. The high effectiveness of solidification/stabilization process was gained in high pH values (9–11).