Photocatalytic degradation of the acetaminophen by nanocrystal-engineered TiO2 thin film in batch and continuous system

• Photocatalytic activity was improved in TiO₂ thin film by rapid thermal annealing. • Photoreactor was designed for TiO₂ thin film. • Considerable reusability and durability of prepared photocatalysts were studied. Un-biodegradable pharmaceuticals are one of the major growing threats in the wastewaters. In the current study, TiO₂ thin film photocatalysts were designed by nanocrystal engineering and fabricated for degradation of the acetaminophen (ACE) in a photocatalytic reaction under UV light irradiation in batch and continuous systems. The photocatalyst was prepared by sputtering and then engineered by thermal treatment (annealing at 300℃ (T300) and 650℃ (T650)). The annealing effects on the crystallinity and photocatalytic activity of the TiO₂ film were completely studied; it was found that annealing at higher temperatures increases the surface roughness and grain size which are favorable for photocatalytic activity due to the reduction in the recombination rate of photo-generated electron-hole pairs. For the continuous system, a flat plate reactor (FPR) was designed and manufactured. The photocatalytic performance was decreased with the increase of flow rate because the higher flow rate caused to form the thicker film of the liquid in the reactor and reduced the UV light received by photocatalyst. The reusability and durability of the samples after 6 h of photocatalytic reaction showed promising performance for the T650 sample (annealed samples in higher temperatures).     

Experimental continuous sludge microwave system to enhance dehydration ability and hydrogen production from anaerobic digestion of sludge

Dehydrating large amounts of sludge produced by sewage treatment plants is difficult.Microwave pretreatment can effectively and significantly improve the dewaterability and hydrogen production of sludge subjected to anaerobic digestion. The aim of this study was to investigate the effects of different microwave conditions on hydrogen production from anaerobic digestion and dewaterability of sludge. Based on an analysis of the electric field distribution, a spiral reactor was designed and a continuous microwave system was built to conduct intermittent and continuous experiments under different conditions. Settling Volume, Capillary Suction Time, particle size, and moisture content of the sludge were measured. The results show that sludge pretreatment in continuous experiments has equally remarkable dehydration performance as in intermittent experiments; the minimum moisture content was 77.29% in the intermittent experiment under a microwave power of 300 W and an exposure time of 60 sec, and that in the continuous experiment was 77.56% under a microwave power of 400 W and an exposure time of 60 sec.The peak measured by Differential Scanning Calorimeter appeared earliest under a microwave power of 600 W and an exposure time of 180 sec. The heat flux at the peak was 4.343 W/g, which is relatively small. This indicates that microwave pretreatment induced desirable effects. The maximum yield of hydrogen production was 7.967% under the conditions of microwave power of 500 W, exposure time of 120 sec, and water bath at 55°C. This research provides a theoretical and experimental basis for the development of a continuous microwave sludge-conditioning system.     

连续紫外扫描光谱法快速测定废水的化学需氧量

探讨了紫外扫描光谱最佳吸收波段内的吸光度集合所组成的峰面积与被测定废水的COD含量的相关性,同时进行了精密度和标准方法的比对实验,取得较好效果.该方法适用于多成分有机混合物的快速测定.