The role of rhizofiltration and allelopathy on the removal of cyanobacteria in a continuous flow system

Environmental Science and Pollution Research - A continuous flow filtration system was designed to identify and quantify the removal mechanisms of Cyanobacteria (Microcystis aeruginosa) by...     

Effects of thermobarical pretreatment of cattle waste as feedstock for anaerobic digestion

Lab-scale experiments were conducted to assess the impact of thermobarical treatment of cattle waste on anaerobic digestion. Treatment was at temperatures of 140–220 °C in 20 K steps for a 5-min duration. Methane yields could be increased by up to 58% at a treatment temperature of 180 °C. At 220 °C the abundance of inhibitors and other non-digestible substances led to lower methane yields than those obtained from untreated material. In an extended analysis it could be demonstrated that there is a functional correlation between the methane yields after 30 days and the formation rate and methane yield in the acceleration phase. It could be proved in a regression of these correlation values that the optimum treatment temperature is 164 °C and that the minimum treatment temperature should be above 115 °C.     

Study of the solubility and stability of polystyrene wastes in a dissolution recycling process

Dissolution with suitable solvents is one of the cheapest and more efficient processes for polystyrene waste management. In this work the solubility of polystyrene foams in several solvents benzene, toluene, xylene, tetrahydrofuran, chloroform, 1,3-butanediol, 2-butanol, linalool, geraniol, d-limonene, p-cymene, terpinene, phellandrene, terpineol, menthol, eucalyptol, cinnamaldheyde, nitrobenzene, N,N-dimethylformamide and water has been determined.Experimental results have shown that to develop a “green process” the constituents of essential oils, d-limonene, p-cymene, terpinene, phellandrene, are the most appropriate solvents. The action of these solvent does not produce any degradation of polymer chains. The solubility of the polymer in the mentioned solvents at different temperatures has been investigated. The solvent can be easily recycled by distillation.     

The effect of spent bleaching earth ageing process on its physicochemical and microbial composition and its potential use as a source of fatty acids and triterpenes

This study was aimed at investigating the physicochemical and microbiological changes that took place during the ageing process of spent bleaching earth in the presence of autochthonous microorganisms. Research material included fresh spent bleaching earth (SBE₀) and the same material after 3 years of storage at the constant temperature of 20 °C, without aeration and moistening (SBE₃). Changes in the chemical composition of analysed waste material were observed during its ageing process point to a spontaneous bioconversion of fat substance towards formation and/or release of free saturated fatty acids C16:0 and C18:0 (14.3 g 100 g^?1 D.M.), triterpenes (8.48 g 100 g^?1 D.M.), cholesterol (3.29 g 100 g^?1 D.M.), small quantities of carbohydrates and esters (0.80 g 100 g^?1 D.M.). This process was accompanied by other changes in physicochemical parameters of the waste material, such as colour, odour and viscosity, decrease in fat content from 28.27 to 24.6 % and that of soluble forms of metals (Mo, Cu, Fe, Zn, Ni, Cr and Mn), ranging from 25 to 75 %, and an increase in pH, from 3.85 to 4.2. At the same time, changes in the microbial consortium were observed.     

Sorption-desorption behavior of PCP on soil organic matter and clay minerals

Pentachlorophenol (PCP) contamination is a severe environmental problem due to its widespread occurrence, toxicity and recalcitrance. In order to gain a better understanding of the fate of PCP in soils, the role of the soil organic matter (SOM) and clay minerals in the PCP sorption-desorption was studied on two bulk field soils, two subsoils (i.e., SOM or clay-removed soil) and two artificial soils. The two field soils used were a silty loam from New Mexico (NM) containing 10% clay and a sandy-clay-loam from Colombia (CO) South America comprised of 18% clay minerals. The bulk CO soil containing kaolinite sorbed significantly less PCP than the NM soil. All soils depicted an apparent hysteresis during sorption. The CO bulk and subsoils desorbed 14-20% and 15-26% of the sorbed PCP respectively whereas the NM bulk and subsoils desorbed only 4-12% and 5-16%, respectively. Experiments conducted with pure clay and artificial soils indicated that the expandable clay minerals were key sorbent material. Additional studies to investigate the interaction between SOM and clay minerals are needed to fully understand sorptive phenomena.