Applied Mechanics and Materials Vols. 361-363

Abstract: Land treatment process was chosen as the first-stage project in Xingtai Wastewater Treatment Plant located in Xingtai city, Hebei Province, PR China. UNITANK was chosen as the treatment technology in the secondary project in order to ameliorate the drawbacks of large land occupation and inconvenient management. In this paper, the operation modes of sewage treatment system, flush water system and sludge discharging system of UNITANK were discussed in detail on the basis of introduction of the basic structure and the technological process. According to the analysis of the project, it is suggested that UNITANK is more suitable for small or middle wastewater treatment plants with the advantages of simple structure, less land occupation, cost-efficient and reliable operation.

Abstract: Wastewater from hair products was the industrial wastewater typically hard to treat with high concentration ammonia nitrogen (NH₄⁺-N) and the low Carbon to Nitrogen (C/N) ratio. In this study ,a pilot-scale study was conducted on Biological Aerated Filter ( BAF) to deeply remove NH₄⁺-N in wastewater from hair products, which aimed to provide technology support for hair products enterprises.The experiments showed that the optimal conditions of BAF was as following: the ratio of air to water was 19:1, the ammonia nitrogen volumetric load was 0.22 kgm³d^-1, in this situation the removal efficiency of Chemical Oxygen Demand (CODcr) and NH₄⁺-N were respectively from 25.0% to 32.5% and from 90.6% to 92.5%, the NH₄⁺-N concentrations and CODcr in effluent were always under 12 mg/L and 100 mg/L respectively, which meet fully first class discharge standard requirement of Integrated wastewater discharge standard in china (GB8978-1996)(IWDSC). Moreover the experiment demonstrated that BAF returned to normal at the moment of 2.5 hours after the end of backwashing.

Abstract: Using chitosan-modified diatomaceous earth (DE) to treat micro-polluted water by coagulation/flocculation/sedimentation (C/F/S), the results indicated that the modified DE could apparently increase the removal rates of turbidity and UV₂₅₄ in comparison with adding DE alone, and the optimal ratio between chitosan and DE was 1:40. With the compounding of polyaluminium chloride (PAC) and modified DE, the treatment effect was obviously improved by coagulation aid of modified DE under adding the same PAC dosage. The best removal rates of turbidity and UV₂₅₄ reached 96.2% and 47.9% respectively with the PAC dosage of 35 mg/L and the modified DE dosage of 45 mg/L. The results indicated that the treatment effect of micro-polluted water improved with the enhanced coagulation of chitosan-modified DE.

Abstract: Fe (VI) was evaluated to treat municipal secondary effluents derived from wastewater treatment plants. Organic matter and reactive phosphate compounds in wastewater was oxidized by Fe (VI) l, and the formation of adsorbable organic haloids (AOX) as by-products in this study. Additionally, the most probable number (MPN) of cultivable heterotrophic bacteria was also determined. In every case for 100% bacterial inactivation a low Fe (VI) concentration (5 mg L.1) was enough and by this concentration 40% chemical oxygen demand (COD) and 20% total organic carbon (TOC) removal could be obtained on average. Higher Fe (VI) concentration (715 mg L.1) resulted in an even higher organics reduction (depending on the water matrix up to 79% COD and 45% TOC removal). Monitoring AOX concentration during Fe (VI)-treatment, it could be stated that AOX formation was in linear relationship with the applied Fe (VI) concentration, but at higher than about 10 mg L^-1 Fe (VI) concentration this increase became much less than at lower Fe (VI) concentration.

Abstract: This paper reviews the use of ferrate (VI) for water and wastewater treatment. The literature revealed that due to its unique properties (viz. strong oxidizing potential and simultaneous generation of ferric coagulating species), ferrate (VI) salt can disinfect microorganisms, partially degrade and/or oxidise the organic and inorganic impurities, and remove suspended/colloidal particulate materials in a single dosing and mixing unit process. However, challenges have existed for the implementation of ferrate (VI) technology in practice due to the instability of a ferrate solution or high production cost of solid ferrate products. Fundamental study is thus required to explore the new preparation methods focusing on increasing the production yield and products stability and avoiding using hypochlorite or chlorine as the oxidant. Also, the application of ferrate (VI) in drinking water treatment has not been studied systematically and future work in this field is recommended.

Abstract: This review makes a critical assessment of the oxidation a series of inorganic compounds by ferrates eFeVIO₄^2_ ; Inorganic contaminants are found in water, wastewaters, and industrial effluents and their oxidation using iron based oxidants is of great interest because such oxidants possess multi-functional properties and are environmentally benign. Case studies are presented which demonstrate that inorganic contaminants can be degraded in seconds to minutes by ferrate (VI) with the formation of non-toxic products.

Abstract: The aim of our research was to find the better treatment progress for tannery wastewater. It elaborated the source and the quality variation law with time change and harm to environment of the tannery wastewater. Listed all kinds of treatment methods, including physical, chemical, biological. Thought the development trends of tannery wastewater treatment was the combination of multiple progress.

Abstract: Water polluted by molybdenum was treated with the process of pre-oxidation adsorption-coagulation-sedimentation-filtration. Powdered activated carbon can adsorb effectively low concentration molybdenum in water. Potassium permanganate can enhance the adsorption effect of activated carbon. The water treated was up to the Standard for Dinking Water Quality of China, in the condition of molybdenum concentration 0.95 mg/L-1.10 mg/L, turbidity <2 NTU and colority <15 units. And the treatment process is as pre-oxidation 30 min with potassium permanganate concentration of 1 mg/L, adsorption 30 min with powdered activated carbon concentration of 40 mg/L, coagulation 30 min with aluminium polychlorid of 40mg/L and polyacrylamide of 0.8mg/L, sedimentation 90 min, and filtration rate 4 m/h.

Abstract: As more and more non-public fund entering rural drinking water safety engineering project market; it becomes very necessary to built rural drinking water safety engineering project guarantee mechanism. This paper proposes three steps of mechanism design. Firstly, history data is used to fit multivariate linear equation set up describing relationship between bank loss and key risk factors. Secondly, guarantee fee is calculated through model regression, which is threefold of possible bank loss. Thirdly, guarantee fee is adjusted according to variety of key risk factor in the process of project construction and operating.

Abstract: Insulation materials with flexural strength 5.238 MPa and porosity 39.24% obtained at 1050 °C for 0.5 h show that its bulk density of the materials decreased down to 1.252 g/cm³ using clay as aggregate. Due to change the amount of sugar filter mud, the porosity arises from 37.07% to 39.24% and the thermal conductivity decreases from 0.086 to 0.052 W·m^-1·K^-1. The clay and wastes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and chemical elemental analysis. The main crystalline phases of sample observed by XRD are quartz, mullite and anorthite. The insulation materials were manufactured from clay and the optimal proportion of wastes.