Applied Mechanics and Materials Vols. 587-589

Abstract: Discussed with the (MWD) for Nitrogen Oxide interference of the mercury determination in wastewater, studied the method of elimination volatile nitrogen oxides rapidly. Optimized the conditions by microwave-digestion hydride generation atomic absorption method for determination of mercury in daily chemical .The detection limit of the method was 0.4μg/L, the lower limit of quantification was 1.2μg/L, the relative standard deviation determined by spiked samples is 1.5% and recovery from 94% to 103%.

Abstract: In existing literature ,there is no unified time for the evaporating excessive acid to microwave digestion solution of different samples. a new method was developed .The interference from nitrite ion and volatile nitrogen oxides which were generated during digestion were quickly removed by the adding urea and heating with boiling water. The interference from nitrate was studied. Optimized conditions of determination of arsenic with hydride generation atomic absorption spectrometry. The detection limit was 0.3μg·L^-1 and minimum quantitative detection limit was 1.0μg·L^-1, the relative standard deviation of standard addition method in sample was 1.1% and recovery from 98 % to 102%.

Abstract: This paper explored the electrochemical oxidation of coking wastewater with Ti/RuO₂-IrO₂ anode. The effects of electrodes connections, area-volume ratio and aeration on the removal efficiency were studied and the ammonia removal mechanism was investigated. The results show that the highest NH₄⁺-N and COD removal efficiency and current efficiency are achieved at the area-volume ratio of 14.44m²/m³ and electrode distance of 0.5cm. Unipolar connection is better than bipolar connection. For electrochemical oxidation of ammonia, the chloride ion is the main factor affecting nitrogen removal. NH₄⁺-N is removed mainly by the oxidation of hypochlorous.

Abstract: The article reveals unsatisfactory condition of contemporary sewage systems and structures and contains analyses of modern approaches to design, construction, reconstruction and service of such systems. Comprehensive approach is pointed out that means use of IT methods as a part of the entire problem and the entire system e.g. sewage network, pumping stations and waste water treatment plants. Authors also give the example of the software used nowadays.

Abstract: The article touches upon researches carried out with biofilters, describes stages of laboratory experiment and gives data and conclusions obtained on each of them.

Abstract: The article touches upon methods and technologies of nitrogen removal. Characteristic features, necessary conditions and technological schemes are listed. There are also ways to intensify existing methods are shown.

Abstract: Constructed wetlands (CW) have been gaining increasing international interest and application because of their unique purification and ecology. Numerous studies have reported that plants or hydraulics influence pollutants removal in CW but the reasons and the relationship between them remain poorly known. This study experimentally investigated the effect of moved wastewater on oxygen release from roots and pollutants removal. Experimental results have demonstrated that more oxygen was released from roots of wetland plants with higher hydraulic loading rate. substrate water DO levels and pollutants removal are accordingly followed by the same pattern as dischargeable oxygen release rate which exhibits diurnal fluctuations. Moved wastewater in CW will stimulate root oxygen release, and stimulate organics and nitrogen removal by increasing oxygen supply for the processes of aerobic degradation and nitrification.

Abstract: Ability of plants to degrade waste water pollutants was studied in model experiment. The following aquatic macrophytes were used: Eichhornia crassipes, Cyperus alternifolius, Elodea densa and a mix of plants. Industrial and municipal waste water diluted by tap water to content 10% and 20% were used as a growth media for plants. Concentration of TOC, TN, chlorides and sulfates was measured in water during 7 days of incubation. The best results were obtained for Eichhornia crassipes which was able to decrease TOC and TN in water in 3 days of incubation: for TOC (in mg/l) from 47 to 24 (20% industrial waste water) and from 25 to 10 (20% municipal waste water); for TN (in mg/l) from 5,6 to 1,2 (20% industrial waste water) and from 2,5 to 0,35 (20% municipal waste water). Other plants also demonstrated improvement of water quality but were less effective. Concentration of chlorides remained close to initial level. Concentration of sulfates in several cases increased due to oxidation of sulfides.

Abstract: The comprehensive evaluation of water quality is an important foundation work for environmental planning and management.Because of the characteristics of fuzziness and impreciseness of river water system, the water quality assessment model based on the set pair analysis theory (WQA-SPA) for evaluating water quality of the river mainstream is proposed. The WQA-SPA model couples fuzzy logic theory and set pair analysis theory, combining identity、discrepancy and contrary (IDC). According to this model, the water level recognition results and the membership of various levels can be calculated by using the river water quality data. Research shows that the evaluation result is accurate, credible. It has a certain value in the comprehensive evaluation of various types of known systems.

Abstract: An approach to synthesize melanin-formaldehyde resin has been developed. The pigment extracted from chestnut shells, a bio-waste from food industry, was employed as the melanin. The synthesis implemented by a double-catalyzed process, namely, base-catalysis and then acid catalysis. The process was optimized and its performance was evaluated on the basis of the cation exchange capacity of the obtained resin. The optimum reaction condition was found to be base-catalysis using NaOH at pH 11.2, 70 °C and the formaldehyde (37%, m/v) to melanin ratio of 2.33 mL/g for 4 hours and then acid-catalysis by HCl at pH 1.5 and 80 °C for 4 hours. The resin can be used as an effective and inexpensive sorbent for Cu (II) removal from aqueous solutions.