This article describes the improvement of wastewater treatment in a fertilizer plant located in Central Italy (municipality of Vasto). In this facility, water is used for the removal of dust and fluorinated gases from the air. The resulting wastewater contains fluorides and phosphates in hazardous forms. Its treatment ordinarily does not result in a Zero-Liquid Discharge (ZLD) process. To achieve this purpose, several reagents were tested, focusing on the correlation linking pH, type of reagent and the effect on the separation of fluorides and phosphates from the wastewater. It was eventually found, and explained with a model, that hydrated lime at pH = 12 was so effective as a precipitating agent that phosphate and fluoride separation reached a value of 99.9%, thus allowing for reuse of the water in the plant process. Furthermore, phosphates and fluorides precipitated in a non-hazardous form, so that the material could also be recycled. In synthesis, wastewater treatment of the fertilizer plant was upgraded so that it became a ZLD process coupled with the recovery and recycling of fluorides and phosphates.
The textile industry is a source of significant amounts of cellulosic waste that can be processed into promising sorbents. The aim of study was understanding the adsorption behavior of metal ions on cellulose surfaces obtained from cellulose textile waste of light industry. Previous studies have shown that unmodified cellulose-based ion exchange resins obtained at different pH values were able to remove metal ions from aqueous solution. In present work the cellulose-based ion exchange resins were prepared by H2SO4 hydrolysis of initial waste product with following neutralization up to different pH and drying at 80 °C. Based on the fractional composition of powdered sorbents, the weighted average particle size of the sorbents used is determined: sorbents with pH = 1.5 - 3 ≈ 0.57 mm; sorbents with pH = 5 - 7 ≈ 0.14 mm. The IR analysis of the elemental composition of the particles showed the presence of bound sulfate groups in the powder sorbent with pH = 1.5-3. The results of experiments showed that the modification of the surface of the cellulose waste with sulfuric acid increased the effect of adsorption of Ni, Fe and Pb ions from an aqueous solution. It has been established that the electrostatic interaction between surface functional groups plays a significant role in the adsorption properties of the sorbents obtained. The affinity of sulphonic acid resins for cations generally varies with the ionic size and charge of the cation. This study showed that adsorption capacities of studied metals were in the order of Fe3+<Pb2+<Ni2+. Resulting cellulose particles have sulfate groups on their surface, which have wide range of applications for the removal of heavy metal ions from wastewater.
At present, much attention is paid to improving the production of synthetic rubbers. The introduction of new technologies to increase the productivity of the process, more fully and rationally use valuable hydrocarbon raw materials, reduce environmental pollution and improve the quality of the products is an important and urgent task. Equally important in this case is the selection of new coagulating agents used in the technology of rubber release from latex. The main requirements for coagulating agents used in the technology of rubber release from latex are: availability, low cost, non-toxicity, ease of cleaning of sewage coming to treatment facilities from them. The possibility of application of the beet-sugar production waste - molasses for beet-lean depletion - in the technology of producing butadiene-styrene rubber SKS-30 ARC has been studied. A feature of the behavior of molasses, as a coagulating agent, is shown when isolating rubber from latex. It has been established that the consumption of molasses in the isolation of butadiene-styrene rubber from latex is closely related to the consumption of acidifying agent - sulfuric acid. The higher the molasses input for coagulation, the higher the consumption of sulfuric acid to maintain the pH of the medium at the required level. The temperature of the process did not have a significant effect on the completeness of the release of rubber from latex. The extracted crumb of rubber was separated from the aqueous phase (sulfur), washed with warm softened water and dried. On the basis of the rubber obtained, rubber mixtures were prepared using standard components and vulcanized. Rubbers obtained on the basis of rubber SKS-30 ARC, in their indicators meet the requirements.
The process of methionine extracting from food enterprises wastewater by ion exchange sorption was studied in work. The optimal conditions for conducting the process of sorption and desorption of methionine on polycondensation cation exchanger KU-5 were determined. The maximum coefficient of ion-exchange equilibrium from aqueous salt solutions in a strongly acidic medium (pH 2) at the sodium sulfate concentration in the equilibrium solution of 2.1 mg-Eq/ml was determined by the analysis of the isotherms of methionine sorption in the sodium form of the KU-5 cation exchanger. Methionine desorption was carried out with a 1% NaOH solution, which allowed crystalline methionine being extracted from the eluate at pH 6.5 at room temperature, this crystalline methionine meeting the requirements of regulatory documentation. An automatic control scheme where the adsorber operates in a closed cycle: sorption–acidic wastewater displacement–desorption and activation of cation exchanger–regenerating solution displacement–sorption, was proposed to optimize the process. The method allows additional measurement of the modes and changing the equipment parameters depending on the rational parameters of the sorption/desorption. This approach allows complete extraction of the target component from wastewater, as well as increases the sorbent use completeness and energy and resource-saving at the enterprise.
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