Resource-Saving Technology Based on Sewage Sludge

The issues of waste disposal are currently having a global technological and economic complexity. The severity of the environmental problem is specified by the accumulation of large volumes of various wastes, including sewage sludge (SS). Modern technologies can provide its disposal with environmental and economic benefits. SS is a rich source of nutrients with a high fertilization potential. This work aims to study the utilization of wastewater sludge in recycling technology for agriculture. The composition of urban sewage sludge and its impact on the properties of gray forest soil were studied. It was shown that its application in a dose of 40-60 t/ha promoted an increase in the content of humus, mobile phosphorus and exchangeable potassium in the soil and a decrease in acidity. The noted increase in the content of the studied heavy metals upon the introduction of various doses of sludge did not exceed the approximate permissible concentration (APC) in the soil. The results showed that the use of SS as a fertilizer restores the balance of organic matter in soils and improves their agroecological properties. This technology, as a safe way of recycling waste into a valuable complex fertilizer, contributes to resource conservation

Applicability of the modified diatomite for treatment of wastewater containing heavy metals

The paper studies various modifications of diatomite, aiming at creating sorbents for wastewater purification from heavy metal ions. Diatomite of the Akhmatovskoe deposit of the Penza region was considered as a raw material. The processes of physical and chemical modification of diatomite were investigated. Adsorption isotherms were constructed, quantitative characteristics of adsorption of copper ions on the surface of modified sorbents were obtained. A chemical modification (acidic and alkaline) is proposed, which results in an increased adsorption capacity for heavy metal ions. The applicability of diatomite for the purification of highly concentrated wastewater containing heavy metals is shown

Cubic Nonlinearity of Tellurite and Chalcogenide Glasses: Terahertz-Field-Induced Second Harmonic Generation vs. Optical Kerr Effect

Third-order nonlinear susceptibilities χ3−2ω;ω,ω,0 and χ3−ω;ω,−ω,ω responsible for electric-field-induced second harmonic generation and the optical Kerr effect were measured and directly compared for tellurite and chalcogenide glasses. The nonlinear coefficients were found by measuring the second harmonic radiation from samples under the action of an external field of terahertz pulses and by the classical z-scan technique, respectively. The influence of ambient air and helium gas on second harmonic generation was analyzed. It was demonstrated that both susceptibilities χ3−2ω;ω,ω,0 and χ3−ω;ω,−ω,ω have close absolute values, which shows the dominant role of nonresonant electronic nonlinearity in the studied glasses

Cubic Nonlinearity of Tellurite and Chalcogenide Glasses: Terahertz-Field-Induced Second Harmonic Generation vs. Optical Kerr Effect

Third-order nonlinear susceptibilities χ3−2ω;ω,ω,0 and χ3−ω;ω,−ω,ω responsible for electric-field-induced second harmonic generation and the optical Kerr effect were measured and directly compared for tellurite and chalcogenide glasses. The nonlinear coefficients were found by measuring the second harmonic radiation from samples under the action of an external field of terahertz pulses and by the classical z-scan technique, respectively. The influence of ambient air and helium gas on second harmonic generation was analyzed. It was demonstrated that both susceptibilities χ3−2ω;ω,ω,0 and χ3−ω;ω,−ω,ω have close absolute values, which shows the dominant role of nonresonant electronic nonlinearity in the studied glasses

Measurements of fluence profiles in femtosecond laser sparks and superfilaments in air

We investigate the nonlinear propagation of multiterawatt femtosecond laser pulses at 800 nm wavelength in air, under different external focusing conditions. We profile the laser beam in the vicinity of the nonlinear focus using a technique based on the dependence of the single-shot ablation threshold for gold on the angle of incidence of the laser beam on the sample. Under very tight focusing conditions (f number similar to 15) we observe the propagation regime reminiscent of the nanosecond optical breakdown. No clear individual filaments are formed across the beam, and the estimated peak intensity surges to at least 200 TW/cm(2). As the external focusing is loosened to f number similar to 125, we observe the transition to the multifilamentation regime. Distinct individual filaments are formed before the linear focus while the peak intensity reaches similar to 80 TW/cm(2). Once formed, the filaments do not coalesce into a single or few superfilaments as they pass through the focus zone. Our experimental observations are supported by numerical simulations.U.S. Air Force Office of Scientific Research under MURI [FA9550-16-1-0013]; Laserlab-Europe Project [HIJ-FSU002344]; Friedrich-Schiller-Universitat Jena; University of ArizonaThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]