By studying alkaline-activated complex systems with coal gangue calcined at 750°C and slag, the results can show that under the action of soluble glass, when the weight fraction of calcined coal gangue was less than 30%, mechanical strength of composite systems may be more than 40 MPa. But when the weight fraction of calcined coal gangue is higher than 60%, the strength of complex systems was decreased faster than that of alkali-activated slag cementitious materials. X-ray diffraction (XRD) method and determination of chemically combined water content were used to study hydration course of alkali-activated cementitious materials. The results can show that the major hydration product was zeolite and the change of chemically combined water content was consistent with the results of strength development.
In order to reduce the external nutrient loads in Lake Taihu, it is known that controlling nutrient input is the most effective way of reducing the risk of blooms. In this regard, simultaneous nitrogen and phosphorus removal by using a combined system consisting of an anaerobic baffled reactor and an aerobic membrane bioreactor for municipal wastewater treatment under the operation condition (a hydraulic retention time of 7.5 h, a recycle ratio of 200% and dissolved oxygen of 3 mg/L) was investigated. The results demonstrated that the process had a good ability to adapt to the influent shift, and was able to achieve the simultaneous nutrient removal of both two kinds of municipal wastewaters effectively with the high removal efficiencies of chemical oxygen demand, ammonium, total nitrogen, and total phosphorus more than 89, 98, 65, and 83% respectively. Analysis of fluorescence in situ hybridization showed that ammoniaoxidizing bacteria, nitrite-oxidizing bacteria, and phosphorus accumulating organisms all slightly decreased may be due to the sudden drop of influent nutrient. In addition, the high sum of the three kinds of bacteria may be the underlying reason why the CAMBR process was efficient for nitrogen and phosphorus removal.
A combined ABR-MBR process consisting of an anaerobic baffled reactor (ABR) combined with an aerobic membrane bioreactor (MBR) treating municipal wastewater was investigated at controlled pH range 6.5-8.5 and at constant temperature 25 ± 1°C. Total nitrogen (TN), ammonia (NH 4 ? -N), total phosphorus (TP), and chemical oxygen demand (COD) removal performances were evaluated by analyzing the mechanism for efficient nutrient removal. The results showed that the average removal rates of COD, NH ? -N, TN, and TP removal rates of 13, 10, and 18 %, respectively, and the membrane retention reduced TP 0.17 mg/L. The process was able to maintain a stable performance with high-quality effluent. Analysis of the results by fluorescence in situ hybridization showed that the abundance of ammonia-oxidizing bacteria, nitriteoxidizing bacteria, and phosphorus accumulating organisms as percentages of all bacteria in each compartment was stable. The enriched microorganisms in the system appear to be the main drivers of the process efficient for nutrient removal.
Activation of coal gangue from Yixing was done by the method of addition of calcium during calcination. Structural characteristic and cementitious properties of activated samples were analyzed. And then hydration degree of activated coal gangue cement was studied. The results show that: thermally and chemically added-calcium composite activation method can improve the activity of coal gangue. At 1050°C, more effective silicate minerals may be in activated samples, with which cement system may have a higher degree of hydration. infra-red(IR) spectra shows that large number of new mineral peaks can occur in activated sample, and with extending of hydration age mineral peaks gradually decreases until it disappears.
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