Treatment of dairy manure using the microwave enhanced advanced oxidation process under a continuous mode operation

The microwave enhanced advanced oxidation process (MW/H₂O₂-AOP) was used to treat dairy manure for solubilization of nutrients and organic matters. This study investigated the effectiveness of the MW/H₂O₂-AOP under a continuous mode of operation, and compared the results to those of batch operations. The main factors affecting solubilization by the MW/H₂O₂-AOP were heating temperature and hydrogen peroxide dosage. Soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFA) increased with an increase of microwave (MW) heating temperature; very high concentrations were obtained at 90°C. Insignificant amounts of ammonia and reducing sugars were released in all runs. An acidic pH condition was required for phosphorus solubilisation from dairy manure. The best yield was obtained at 90°C with an acid dosage of 1.0 %; about 92 % of total phosphorus and 90 % of total chemical oxygen demand were in the soluble forms. The MW/H₂O₂-AOP operated in a continuous operation mode showed pronounced synergistic effects between hydrogen peroxide and microwave irradiation when compared to a batch system under similar operating conditions, resulting in much better yields.     

Atrazine removal by ozonation processes in surface waters

Abstract

Atrazine (6‐chloro‐N‐ethyl‐N'‐isopropyl‐1,3,5‐triazinedyl‐2,4‐diamine) was treated with ozone alone and in combination with hydrogen peroxide or UV radiation in three surface waters. Experiments were carried out in two bubble reactors operated continously. Variables investigated were the ozone partial pressure, temperature, pH, mass flow ratio of oxidants fed: hydrogen peroxide and ozone and the type of oxidation including UV radiation alone. Residence time for the aqueous phase was kept at 10 min. Concentrations of some intermediates, including deethylatrazine, deisopropylatrazine and deethyldeisopropylatrazine, were also followed. The nature of water, specifically the alkalinity and pH were found to be important variables that affected atrazine (ATZ) removal. Surface waters with low alkalinity and high pH allowed the highest removal of ATZ to be reached. There was an optimum hydrogen peroxide to ozone mass flow ratio that resulted in the highest ATZ removal in each surface water treated. This optimum was above the theoretical stoichiometry of the process. Therefore, to reach the maximum removal of ATZ in a O₃/H₂O₂ process, more hydrogen peroxide was needed in the surface waters treated than in ultrapure water under similar experimental conditions. In some cases, UV radiation alone resulted in the removal of ATZ higher than ozonation alone. This was likely due to the alkalinity of the surface water. Ozonation and UV radiation processes yield different amounts of hydrogen peroxide. Combined ozonations (O₃/H₂O₂ and O₃/UV) lead to ATZ removals higher than single ozonation or UV radiation but the formation of intermediates was higher.     

pH及络合剂对亚铁活化S2 O82-氧化去除活性艳蓝的影响研究

以蒽醌染料活性艳蓝KN-R为目标污染物,研究了pH及不同pH条件下络合剂对于络合的亚铁活化过硫酸钠氧化去除KN-R的影响,并对络合体系与未络合体系进行比较.结果表明,由于PS在酸性条件下降解速度最快及酸性条件下主导自由基SO4-.氧化还原电位大于碱性条件下的.OH,所以酸性条件下KN-R的去除率远大于中性及碱性条件.pH=3时,EDTA体系KN-R 3 h剩余率仅为17.0%,PS的消耗率最低为32.3%,EDTA是酸性条件下的最佳络合剂选择;pH=7时,EDTA、柠檬酸体系3 d后KN-R的剩余率分别为11.3%、12.4%,PS消耗率仅为28.9%、28.0%,是中性条件的最佳络合剂选择;pH=10时,葡萄糖酸、柠檬酸、EDTA、酒石酸体系对KN-R的去除率及PS的消耗率基本相同,均能充当亚铁离子的络合剂.微量的亚铁存在时,络合剂的加入能很好地提高污染物的去除率,3 d后从52.5%提高到79.3%,说明PS适合于污染物的原位化学氧化降解(ISCO).     

脱氮硫杆菌氧化硫化氢过程中的生物氧化和化学氧化

在好氧反应器中研究了不同条件下H2S生物氧化和化学氧化之间的关系.结果表明,在pH为6～8、温度为25～35℃和溶解氧浓度为10.5 mg·L-1时,当硫化氢进气摩尔流速稳定在2.1 mmok·L-1·h-1时,脱氮硫杆菌(Thiobacillus denitrificans)氧化硫化氢的生物氧化速率可达到1.9 mmol·L-1·h-1以上,此时硫化物在液相的累积摩尔速率和H2S出口摩尔流速均很低;化学氧化速率随pH、温度和溶解氧浓度的增加而增大,可达到0.33 mmol·L-1·h-1～0.45 mmol·L-1·h-1;化学氧化速率在最佳菌体生长条件范围内占总氧化速率的比值较小,为8.6～19.1%,而随着pH值、温度的降低这一比值上升至29%～43.7%.     

COD/SO42-值对硫酸盐废水厌氧消化的影响

采用间歇试验方式,研究了COD/SO₄^2-值对硫酸盐废水厌氧消化的影响.试验结果表明,COD/SO₄^2-值是影响厌氧消化处理效果的主要参数.本试验中,COD/SO₄^2->15,硫酸盐还原作用对厌氧反应器影响甚微;COD/SO₄^2-=5-15时,硫酸盐还原作用对厌氧反应器产生轻度抑制,相对产甲烷率为79.2%-94.7%;COD/SO₄^2-=0.5-5时,反应器受中度抑制,相对产甲烷率为61.6%-79.2%;COD/SO₄^2-<0.5时,反应器受严重抑制.COD/SO₄^2-≥1时,相对产甲烷率与COD/SO₄^2-值之间有很好的线性关系.     

实验室模拟研究硫酸铵和甘氨酸对乙醇醛与胺反应体系生成棕碳的影响

二次有机气溶胶是有机气溶胶的重要组成部分。大气中羰基化合物与胺/铵反应可以产生吸光性有机气溶胶（如棕碳）,对大气辐射和全球气候产生深刻影响。本文模拟研究了大气中硫酸铵和甘氨酸对乙醇醛与胺（如甲胺、甘氨酸）反应生成棕碳的影响。通过对反应溶液紫外—可见吸收光谱和反应动力学分析,发现硫酸铵对反应体系棕碳的生成起抑制作用,而甘氨酸和甲胺的混合可以协同促进棕碳生成;通过对产物进行质谱分析,发现反应机理主要为半缩醛/缩醛反应以及含氮化合物的亲核加成;通过对产物有机碳进行分析,发现当硫酸铵参与反应时,有利于大分子二次有机碳生成。这些发现对棕碳在大气中的形成途径、乙醇醛在化学模型中对棕碳形成的贡献以及对大气中其他羰基行为的预测具有重要意义。     

利用含铝废硫酸和废铝渣制备聚合硫酸铝

以含铝废硫酸和废铝渣为原料制备聚合硫酸铝（PAS）。优化了废铝渣的酸溶条件,确定了合适的稳定剂和碱化剂。实验结果表明：在酸溶反应温度为80 ℃、酸溶反应时间为40 min、以20 g/L Ca（OH）₂溶液为碱化剂、以加入量为60 mg/L的固体柠檬酸为稳定剂的条件下,制备的PAS比聚合氯化铝（PAC）和Al₂（SO₄）₃具有更优异的混凝性能。该工艺可回收利用废铝渣和含铝废硫酸,从而达到综合利用的目的。     

秸秆生物炭对有机染料的吸附作用及机制

研究了裂解温度分别为500℃和700℃的两种水稻秸秆生物炭(分别标记为W500、W700)对有机染料日落黄和亚甲基蓝的吸附作用及机制.同时,针对实际印染废水的特点,考察了反应温度、p H和硫酸盐对吸附去除效率的影响.结果显示,生物炭对两种染料的吸附均符合准二级动力学方程,等温吸附曲线均可用Freundlich模型较好地描述,但其对两种染料的吸附机制显著不同.生物炭对阳离子染料亚甲基蓝的吸附主要通过离子交换作用,随着生物炭裂解温度升高,其极性基团减少,离子交换作用减弱.生物炭对阴离子染料日落黄的吸附则主要通过生物炭芳香结构与日落黄分子芳环之间的π-π相互作用,随裂解温度升高,生物炭芳香化程度增大,π-π作用随之增大;生物炭对两种染料的吸附去除效率均随反应温度的升高(5~45℃)而增大,且在3p H11、硫酸盐浓度25~2500 mg·L~(-1)的变化范围内,吸附去除效率均保持稳定.     

交流变频磁化聚合硫酸铁混凝处理造纸废水

采用交流变频磁场预处理聚合硫酸铁(PFS),用于混凝处理造纸废水。考察了有无磁化作用、PFS加入量、磁化强度、磁化频率、磁化时间等因素对造纸废水的COD去除率和色度去除率的影响。实验结果表明:磁化PFS对造纸废水的处理效果较未磁化时明显提高;在PFS加入量为1 000 mg/L、磁化强度为6 mT、磁化频率为90 Hz、磁化时间为3 min的条件下,处理初始COD为650 mg/L、初始色度为180倍的造纸废水,COD去除率为93.22%,色度去除率为88.89%。     

Cu~(2+)/UV/H_2O_2去除水中盐酸四环素及动力学研究

对比了UV、Cu~(2+)/H_2O_2、UV/H_2O_2、Cu~(2+)/UV/H_2O_2体系对盐酸四环素(TC)的降解效果,考察了Cu~(2+)/UV/H_2O_2体系降解TC的影响因素,并进行了动力学分析。实验结果表明:Cu~(2+)的加入明显增强了UV/H_2O_2体系对TC的降解效果,反应60 min时,Cu~(2+)/UV/H_2O_2体系对TC的降解率相比UV/H_2O_2体系提高了24.82%;Cu~(2+)的最佳投加量为120μmol/L;pH对TC的降解影响较小;H_2O_2投加量、温度、紫外灯功率的增加均会增加TC的降解率。Cu~(2+)/UV/H_2O_2体系中TC的降解可用拟二级动力学方程描述,TC降解的活化能为15.56 kJ。