Decolourization and removal of some organic compounds from olive mill wastewater by advanced oxidation processes and lime treatment

Background Olive mill wastewater (OMW) generated by the olive oil extracting industry is a major pollutant, because of its high organic load and phytotoxic and antibacterial phenolic compounds which resist biological degradation. Mediterranean countries are mostly affected by this serious environmental problem since they are responsible for 95% of the worldwide oliveoil production. There are many methods used for OMW treatment, such as adsorption, electro coagulation, electro-oxidation, biological degradation, advanced oxidation processes (AOPs), chemical coagulation, flocculation, filtration, lagoons of evaporation and burning systems, etc. Currently, there is no such economical and easy solution. The aim of this study was to evaluate the feasibility of decolourization and removal of phenol, lignin, TOC and TIC in OMW by UV/H₂O₂ (AOPs). The operating parameters, such as hydrogen peroxide dosage, times, pH, effect of UV and natural sunlight were determined to find the suitable operating conditions for the best removal. Moreover, there is no study reported in the literature related to the use of UV/H₂O₂ and lime together in OMW treatment. Methods OMW was obtained from an olive-oil producing plant (Muğla area of Turkey) which uses a modern production process. No chemical additives are used during olive oil production. This study was realised by using two different UV sources, while taking the time and energy consumption into consideration. These two sources were mercury lamps and natural sunlight. Before starting AOPs experiments, one litre of OMW was treated by adding lime until a pH of 7.00. Then, 100 ml was taken from each sample, and 1 to 10 ml of a 30% H₂O₂ (Riedel-deHaen) solution was added. These solutions in closed vessels were laid in the natural sunlight for a week and their compositions and colour changes were analysed daily by UV-Vis spectrophotometer. At the end of the one-week period, they were treated with lime. In this study, the effect of changes in the initial pH, times and H₂O₂ concentrations on removal was investigated. At the end of all experiments, changes in colour, phenol, lignin, TOC and TIC concentrations were analysed according to standard methods. Results and Discussion In the samples exposed to natural sunlight and having an H₂O₂/OMW ratio of 3 ml/100 ml, a significant colour removal was achieved approximately 90% of the time at the end of 7 days. When the same samples were treated with lime (pH: up to 7), 99% efficiency was achieved. When phenol and lignin removals were examined in the same concentration, phenol and lignin removal were found 99.5%, 35%, respectively. However, for maximum lignin removal, more use of H₂O₂ (10 ml H₂O₂/100 ml OMW) was found to be necessary. Under these conditions, it was found that lignin can be removed by 70%, but to 90% with lime, at the end of a seven-day period. Rate constants obtained in the experiments performed with direct UV were found to be much higher than those of the samples exposed to natural sunlight (k^a _lignin = 0.3883 ≫ k^b _lignin = 0.0078; k^a _phenol = 0.5187 ≫ k^b _phenol = 0.0146). Moreover, it should be remembered in this process that energy consumption may induce extra financial burden for organisations. Conclusions It was found, in general, that colour, lignin, total organic carbon and phenol were removed more efficiently from OMW by using H₂O₂ UV and lime OMW. Moreover, in the study, lime was found to contribute, both initially and after radical reactions, to the efficiency to a great extent. Recommendations and Perspectives Another result obtained from the study is that pre-purification carried out with hydrogen peroxide and lime may constitute an important step for further purification processes such as adsorption, membrane processes, etc.     

电化学传感法测定水中亚硝酸盐

借助于简单可控的在线电聚合方法,溴酚蓝被修饰到玻碳电极表面,制备了聚溴酚蓝修饰玻碳电极。实验表明,聚溴酚蓝薄膜对于亚硝酸盐的电化学氧化具有很好的催化作用。经实验优化,聚溴酚蓝膜的最佳厚度为聚合20圈,最佳的检测底液为pH=4.0的0.01 mol/L磷酸盐缓冲溶液。亚硝酸盐在传感器上的电化学氧化是一个双电子双质子参与的过程。在最佳检测条件下,亚硝酸盐的氧化峰电流与其浓度在0.02~109.1μmol/L范围内有良好的线性关系,检测限低至5 nmol/L(S/N=3),所制备的亚硝酸盐传感器线性范围宽、检出限低、稳定性和重现性好、抗干扰能力强,将传感器应用于东湖水样中亚硝酸盐含量的测定,结果令人满意。     

硝基苯甲酸结构对其在EPDM膜中萃取效果的影响

以3种取代基位置不同的硝基苯甲酸为研究对象,研究了辛醇/水分配系数、溶解度、摩尔体积、分子极化率和偶极矩5种结构参数对硝基苯甲酸在三元乙丙橡胶（EPDM）膜中萃取效果的影响。实验结果表明：EPDM膜对硝基苯甲酸有一定的去除效果,邻、间、对硝基苯甲酸的去除率分别为27.1%、32.4%和41.6%;取代基位置的不同使硝基苯甲酸的去除效果出现差异,其疏水性越强越易在EPDM膜中溶解和渗透;硝基苯甲酸的去除率和透过率与其辛醇/水分配系数和分子极化率正相关,与溶解度负相关;硝基苯甲酸的去除率可用分子极化率和偶极矩两个结构参数进行预测。     

过磷酸钙与石灰混施对污染农田低累积玉米生长和重金属含量的影响

通过田间实验,研究了过磷酸钙和石灰混施对重金属污染农田上低累积玉米产量以及籽粒、茎叶重金属含量的影响,并分析了施用过磷酸钙和石灰后土壤pH和有效重金属含量的变化。结果表明,与单施过磷酸钙和单施石灰相比,过磷酸钙和石灰混施更能显著提高玉米生物产量,且过磷酸钙和石灰均有一定的后效。单施石灰处理、石灰与过磷酸钙混施处理都均显著降低玉米籽粒Cd、Zn和Cu含量,其中以中量(0.4 kg/m2)、高量石灰(0.6 kg/m2)+中量过磷酸钙(0.2kg/m2)处理效果最佳,其玉米籽粒Cd、Zn和Cu含量降低到了国家食品卫生标准允许的含量水平。石灰处理均不同程度地提高了玉米籽粒Pb含量,配施过磷酸钙也不能明显降低玉米籽粒Pb含量,但仍低于饲料卫生标准允许的含量水平。另外,单施石灰处理和石灰与过磷酸钙混施处理均显著降低了玉米茎叶Cd、Pb、Zn和Cu含量,可以安全用作有机肥。     

含氟离子和氯离子酸性废水处理技术

本实验研究了石灰乳和铝酸钠处理废水中的氟离子和氯离子的效果。通过正交实验得出:影响除氟离子效果因素的主次顺序为:pH值>氟离子浓度>反应时间;影响除氯离子效果因素的主次顺序为:氯离子浓度>铝酸钠与氯离子的质量浓度比>反应时间。通过单因素实验得出:在pH=9、反应时间为5 min的条件下,废水中氟离子含量可由370.37mg/L降低到2 mg/L以下,去除率可达99.45%;在铝酸钠与氯离子的质量浓度比为1∶10,反应时间为5 min的条件下,废水中氯离子含量可由503.4 mg/L降低到201 mg/L以下,去除率可达60%。     

造纸白泥和粉煤灰的添加对污泥消化液中氮磷回收的影响

污泥厌氧消化液中含有丰富的氮磷,若直接排放到环境中,将会对附近水体造成严重污染。由于消化液中Mg^2＋和Ca^2＋的含量很低,严重影响了氮磷的回收效果。把造纸白泥和粉煤灰引入到污泥厌氧消化液氮磷的回收当中,可以明显地提升消化液pH和提高PO4^3-P和NH3-N回收率。实验结果表明：当造纸白泥添加量为4g／（L·h）时,曝气12h后,pH可达10．19,此时PO4^3-P和NH3-N回收率分别达到64％和45％;而当粉煤灰添加量为4g／（L·h）时,曝气12h后,pH达到9．63,PO4^3-P和NH3-N回收率分别为46％和41％。但仅用曝气方式处理,12h后,pH值仅为8．52,PO4^3-P和NH3-N回收率分别只有20％和18％。实验结果还表明,水力停留时间（HRT）越大,pH上升速度越快,幅度越大,氮磷的回收效果就越好。     

石灰污泥共热法在水泥煅烧中的应用

利用水泥窑尾的高温废气干化污泥是处理污泥且节约能源的新方法。为了模拟窑尾废气干化污泥的生产工艺,试验对污泥与石灰共热干化,研究了石灰(CaO)在污泥热干化过程中作用,可提高污泥的干化速率,减少有害气体排放及提高干化污泥的稳定性。研究表明,当石灰掺量质量百分含量达到10%时,250℃下污泥干化速率同比提高了19.6%;释放的H2S气体减少了95.1%;污泥中有机物含量减少了77.87%。     

两性高分子重金属螯合絮凝剂的合成及其对Cu(Ⅱ)的去除性能

合成了一种新型两性高分子重金属螯合絮凝剂聚(氯化二烯丙基甲基羟丙多胺基铵)基二硫代甲酸钠(PDAMHACDTC),采用元素分析、红外光谱、紫外光谱和核磁共振谱对其结构进行表征。考察了其对含Cu2+废水的处理效果,以及絮体的沉降速度;测定了微絮体的ζ电位,采用扫描电镜考察了絮体的形貌。结果表明,当PDAMHACDTC中—CSS-与Cu2+的物质的量之比接近2∶1,对Cu2+的去除率大于99.7%,残余Cu2+浓度远低于国家污水综合排放一级标准0.5 mg/L;在相同—CSS-投加量时,形成的微絮体的ζ电位和絮体沉降速度分别比以聚(二甲基二烯丙基氯化铵-丙烯酰胺)为母体合成的两性高分子螯合絮凝剂(ACPF)形成絮体大,说明PDAMHACDTC比ACPF更利于中和絮体上过剩负电荷,促进絮体的形成和生长。     

石灰投加与搅拌对生态厕所的灭菌效果

以发展中国家农村地区的卫生条件改善为目的,开展了简易生态厕所的粪便堆肥处理实验。在投加石灰作为抑菌剂的条件下,研究了搅拌混合对杀灭致病微生物的影响,以及使堆肥终产物达到可接受风险值所需的最佳搅拌条件。实验确定了石灰的投加量,并应用Beta-Possion模型对堆肥处置过程中致病微生物对暴露人群的健康风险进行评价,从而从健康风险控制的角度确定了最佳的搅拌次数。研究结果表明,石灰投加量约占堆肥干重1.5%,手动搅拌50次,经搅拌后放置12 h能达到可接受的风险值(3.2×10-5)。     

中空纤维膜超滤聚丙烯酸钠溶液

研究聚丙烯酸钠（PAAS）溶液的超滤行为,考察各操作参数对膜通量（J）和截留系数（R）的影响,结果表明,J随运行时间延长衰减不明显,随压差增大呈线性递增,随温度升高而增大,pH高于5时J基本不变;R随压差增大或温度升高均下降,随pH增大而增大。建立膜阻力（rf）模型,研究影响rf的主要因素,发现,rf随压差增大而增大,随温度升高而减少,pH低于5时rf随pH增大而迅速下降。研究PAAS溶液浓缩过程,当体积浓缩因子为16时,J衰减明显,截留液PAAS浓度（Cr）呈线性递增,渗透液PAAS浓度（Cp）在较长时期内基本不变,至浓缩后期,Cp轻微下降。以去离子水对浓缩液予以洗涤,随着洗涤液体积增大,Cr轻微下降,Cp逐渐趋于零。