Yearly Archives: 2016

Abstract:
The study assessed the efficiency of the coagulation process of wastewater with petroleum hydrocarbons content, by using mixed coagulants derivatives of polyaluminum chloride, (characterized by the molar ratio OH : Al = 2.4), mixed with various amounts of chitosan. Systematic study was conducted to define the mixed coagulant, respectively chitosan:polyaluminum chloride product, by relating its two components, within the context of optimal dosage used in the coagulation process, determined experimentally by the Jar Test method. The coagulation efficiency was examined by conventional parameters: pH, turbidity, COD, TOC, TPH (Total Petroleum Hydrocarbons) and the unconventional parameter – absorbance at wavelength 254 nm, A 254. Coagulation performance determined with the mixed chitosan – polyaluminum chloride coagulant was reported to the results obtained by coagulating with polyaluminum chloride in the absence of chitosan. The results suggest that the use of mixed chitosan – polyaluminum chloride coagulation agent, prepared at a ratio of chitosan : Al = 0.6, can significantly reduce the optimum dose of Al, more than 50%, and obtain treated samples with the same characteristics as the samples treated with optimal doses of polyaluminum chloride

Abstract:
For the first time, phytochemical stimulants that intensify the process of fermentation and increase the methane content in the produced biogas were applied in the technology of obtaining biogas through anaerobic fermentation. The residual marc obtained from distillation of bio-alcohol from non-standardized raw-materials has served as experimental substrate. A series of substances consisting of various derivatives of phytochemical compounds such as flavonoids, tannins, mono-, di and triterpenoids, sterols, triterpene- and sterol- saponins, carotenoids that manifested themselves as more active stimulants of methane production than the diterpenoid sclareol, or triterpenoids squalene and betulinol, all from the terpenic compounds group were tested experimentally. The laboratory experiments that were performed have applied these three compounds to the anaerobic fermentation environment in concentrations varying between 10-5 -10-3% by mass of substrate, which demonstrated an increase of the ratio of fermentation up to 2-3 times and an increase of the methane content from 50-60 up to 80%. Monoterpenoids, while applied in same quantities, have manifested a reduced intensification of anaerobe fermentation. The investigated flavonoids, tannins and saponins applied in similar conditions of testing have caused the reduction of the content of methane in biogas emissions.

Abstract:
This paper shows the behavior of natural organic matter (NOM) from drinking water under the influence of ultrasonic radiation. Experimental tests were performed by direct sonolysis of a drinking water source (river water) in order to establish the influence of main parameters (water source composition, irradiation time, energy and amplitude of ultrasonic wave, temperature, pH, conductivity) on NOM efficiency degradation emphasized by total organic carbon (TOC) and CODMn indicators. Likewise, UV-VIS spectra were made for the characterization of degradation processes based on nonconventional parameters A254, A280, A365, SUVA. The experimental results highlight maximum 30% efficiency of NOM removal for short irradiation time, two minutes, diminishing of the ultrasonic wave amplitude leading to removal efficiency increasing (for the same 16 kHz frequency and the same energy of the wave).

Abstract:
The composition of groundwater is of interest for drinking water service providers due to its implications upon the potabilisation treatment flow. The paper is presenting two case studies from Romania, each groundwater sources containing ammonium and organic load reactive to chlorine. Oxidation tests for NH4+ were performed using chlorine and sodium hypochlorite on water samples with the following characteristics: NH4+ ≤ 4.4 mg/L and DOC < 1 mg/L. Oxidation tests with chlorine at the breakpoint showed that a weight ratios of Cl2 : N-NH4+≥ 10 : 1 and reaction time of 40 min are needed in order to assure a remanent concentration of NH4+ below the admissible value of 0.5 mg/L, residual chlorine concentrations being in the range of 12-20 mg/L, and THM concentration after 24 h in the range of 102-277 µg/L. Oxidation tests with NaOCl showed that even at high doses of active chlorine (30 mg/L) and long reaction time of 24h, remanent ammonium concentration is higher than the admissible value of 0.5 mg/L, residual chlorine concentration being of mg/L order. In this case, selection of an alternative raw water source or the replacement of classical oxidation technology using chlorine by biological nitrification is needed.

Abstract:
The objective of this study was to determine the possibility of using fly ash amendment optimal doses from a thermal plant, mixed with a fertilizer agent, anaerobically stabilized sewage sludge to reduce stress caused by the presence of large amounts of 113.5 g·kg-1 D.M. of oil product, TPH, (Total Petroleum Hydrocarbons) in polluted soils. The study was conducted in vegetation pots to determine the emergence degree and development of a culture of forage leguminous plants of Lotus corniculatus species, bird’s foot trefoil. The experimental variants were treated with fly ash and fertilized with 500g per vegetation pot of anaerobically stabilized sewage sludge. Studies were done in comparison with experimental versions cultivated with bird’s foot trefoil of polluted soil treated with fly ash, polluted soil fertilized untreated with ash. The addition of fertilizing agent mixed with small amount of fly ash caused a emergence degree of 50-60%, and the reduction of the content of oil product, after 4 months of vegetation, by 29.9%. The maintaining of vegetation in perennial regime specific to this plant species demonstrates the plant tolerance to conditions created by the treatment of polluted soil with adequate amounts of fertilizer and fly ash amendment.

Abstract:
The anaerobic digestion of organic substrates in agricultural waste waters, including from fruit and vegetable processing, winery, canning, etc. industries can be both the way to reduce the pollutants contents, and the source of biogas as well as an alternative energy source. The problem to which resolving this work is addressed, involves the following main issues: energy component, environmental protection, economic development and social improvement. The research involved is focused on developing a new-generation intensive ecological technology and integrated bioreactor for biogas production through the valorisation of agro-industrial wastes which are hazardous being dumped in the natural environment. The technology proposed bears a breakthrough character and is based on the use of natural phyto-catalysts introduced in the digested biomass in micro-concentrations of 10-3 -10-5 %. They are obtained by extraction from natural vegetable feedstock and wastes. It was shown that the phyto-catalysts proposed promote 1,5-2 times acceleration of methanogenic process and increase in biomethane contents in biogas up to natural gas level. Therefore, the capital costs for bioreactors construction and operation could be significantly reduced.

Abstract:
In the processing of grapes and the production of alcoholic beverages, a total of about 100,000 cubic meters of wine lees, vinasse, grain mash and molasses are annually formed and accumulated in the Republic of Moldova. These wastes are characterized by a highly acidic chemical reaction and a high content of water-soluble salts. The pH ranges from 3.4 to 3.8 units. The mineral residue constitutes: 1.9 g/dm3 in vinasse; 12.0 g/dm3 in wine lees; and 14.9 g/dm3 in grain mash. In the composition of monovalent cations, sodium and potassium cations predominate, which may form toxic salts if they penetrate into the soil. The cereal mashes are characterized by a higher potential of salinity and sodium enrichment. Also, these wastes contain primary nutritive elements (NPK) absolutely necessary for plant nutrition and soil fertilization. The total content of NPK in kg/m3 in these wastes constitutes: 1.8 in vinasse; 5.1 in grain mash; 10.6 in wine lees. The dehydrated wine lees and grain mash have a high content of organic matter, 34 % and 51 % respectively. Due to their chemical composition and the highly acidic environment, they have a toxic impact on flora and fauna and a polluting action on surface and ground waters. The administration of two doses of lees (13 and 26 t/ha), of vinasse (300 and 600 m3/ha) and of grain mash (50 and 100 m3/ha) favoured the significant increase of the content of organic matter, mobile phosphorus, and exchangeable potassium in the arable soil layer. The application of wine lees in the dosage of 13 – 26 t/ha ensured a significant increase of grapes by 1.4 – 2.4 t/ha, or by 15 – 25 % more than on the unfertilized control variant, on which 9.5 t/ha were harvested. The vinasse incorporated in a dosage of 300 and 600 m3/ha had a significant impact on the plant productivity as well. The grape harvest constituted an average of 1.0 – 1.1 t/ha or by 11 – 12 % more than on the unfertilized control variant.

Abstract:
A modified biogas technology was elaborated for the treatment of agricultural wastewaters, using the phyto-catalysts for managing the biochemical processes (Covalov, V., Malina, J.F. et al. 2014). To implement the proposed technology, an integrated bioreactor design has been developed. To manufacture a pilot reactor, the available equipment at the “Bardar” Winery (Republic of Moldova) has been used and modernized. As a feedstock for the biochemical digestion a post-distillery vinasse in a mixture with cattle manure was used, to ensure rapid initiation and development of methanogenic process, due to the high contents in methanogenic microorganisms in manure. The ecological effect was due to the preventing of discharges of 15,7 m3 biomass/day, or total amount of 24000 m3 of untreated hazardous concentrated wastes into the natural water bodies (during the bioreactor operation period). Initial concentration of organics in feedstock was 27400 mg O2/l (COD), and after the anaerobic and following microfiltration treatment was approx. 187 mg O2/l.

Abstract:
There is a trend to select, characterize and use new types of surfactants for phase separation processes and developing membranary technologies (e.g. emulsion and liquid membranes) with high yield in removal of: organic substances, metals, dyes, etc, from wastewater. New surfactants are improved continuously, as required because of the dynamics of user technologies and of the indispensability of environmental protection through selection of raw materials without adversely affecting the environment. The paper provides new technological solutions for separation of pollutants from wastewater using gemini and bolaamfifile surfactants, with creation self assembling structures. These new self assembling nanostructures obtained are used in the technology of separation emulsion membranes. Novel technologies based on surfactants are effective, fast, have a convenient price, not require complex utilities, ecologic because reduced the negative environmental impact. Due to specific properties such as micellization, solubility, solubilization, surface activity, surfactants intervene in the membrane production process, in the pre-treatment and their characterization respectively but also in the membrane separation processes (filtration, micellar ultrafiltration) of organic compounds (dyes, intermediaries, phenols, proteins) and metal ions.

Abstract:
New composite biosorbents based on lignocellulose complex, derived from the waste of food industry – apricot pits, and ferrocyanides of d-metals were synthesized. An influence of pretreatment of initial apricot pits by acid-alkali scheme was established. It was found out that such pretreatment leads to an increase in the specific surface area of the lignocellulose material in two times and the total pore volume up to six times. The physical, chemical, structural properties of the obtained materials were investigated. The sorption behavior of initial materials and lignocellulose-inorganic samples toward cesium-137, heavy metals, Methylene blue, gelatin, vitamin B12 was studied. Comparative analysis of the sorption properties of obtained biosorbents based on different ferrocyanides towards different ecotoxicants was carried out. Obtained results allow to state that new composite biosorbents are universal materials for adsorption of radionuclides, heavy metals and organic pollutants from water solutions and can be used in radiochemistry, analytical chemistry, industry, medicine and veterinary.