The efficacy of an oxidation pond in mineralizing some industrial waste products with special reference to fluorene degradation: a case study

The efficacy of the oxidation pond on the outskirts of the 10th of Ramadan, the main industrial city, in Egypt was examined. Samples of wastewater collected from the inlet and the outlet were screened for some priority pollutants. Acenaphthene and fluorene were the most frequently detected polycyclic aromatic hydrocarbons, while dimethyl phthalate was the most frequently detected phthalate ester. The spectrum of pollutants, their concentrations and frequencies were similar in the inlet and the outlet, indicating an inferior mineralization capability of the pond. Several degradative bacterial strains were isolated from the pond and grown on M56 minimal media supplemented with different pollutants as the carbon source. The efficacy of pure and mixed cultures to break down fluorene, the most frequently detected pollutant was examined. Fluorene degradation was fast in the first 10 days, then followed by a slow phase. Mixed culture had a higher rate of fluorene degradation in comparison to pure cultures. High performance liquid chromatography analysis of fluorene degradation showed three degradative metabolites. But GC/MS analysis detected one compound, identified as acetamide. The present work has indicated the poor efficacy of the pond. Lack of primary treatment of industrial effluent at factory level, coupled with shock loads of toxicants that may damage the microorganisms and their degradative capabilities are presumably main factors behind such inferior performance. Moreover, the type of pollutants discharged into the pond tend to fluctuate and change depending on the rate from the factories discharge and work shifts. Such irregular feeding of persistent pollutants may have led to a wash out of specialized strains of bacteria capable to degrade such persistent pollutants.     

Solvent-free mechanochemical mild oxidation method to enhance adsorption properties of chitosan

• Solvent-free chitosan oxidation is obtained by rapid mechanochemical reaction. • Different oxidants induce very diverse physicochemical changes on chitosan. • Oxidized chitosan with persulfate or percarbonate has improved adsorption capacity. • Uptake on oxidized chitosan with persulfate is 125-fold faster than on pristine one. Oxidation has been profitably utilized to improve some properties of chitosan. However, only solvent-based oxidation procedures have been proposed so far, which are hardly feasible at industrial scale in an economic way because of product recovery cost. In this study, a solvent-free, rapid, and effective oxidation method is proposed. It is based on direct solid-state reaction between chitosan and oxidant powder in a mechanochemical reactor. Results prove that by short high energy ball milling (<3 h) it is possible to achieve diverse physicochemical modifications employing different reagents. Apart from polysaccharidic chain shortening, persulfate provokes high amorphization and induces formation of ketonic groups; percarbonate heightens deacetylation degree, preserving in part crystallinity; calcium peroxide merely deprotonates amino groups and increases amorphization degree. Adsorption tests with the azo-dye reactive red 2 show that adsorption capacity of chitosan co-milled with persulfate (974 mg/g milled product), which is the best performing adsorbent, is twice that of pristine chitosan, while adsorption rate is outstandingly boosted (125 times).     

优势微生物强化水解—多级接触氧化工艺处理屠宰废水

结合工程实例,本文对优势微生物强化水解—多级接触氧化处理屠宰废水工艺及设计体会进行了讨论。设计进水COD、BOD5、SS、NH3-N、动植物油为2300~2700mg/L、900~1300mg/L、600~800mg/L、100~120mg/L、70~90mg/L,出水为90mg/L、20mg/L、60mg/L1、0mg/L1、0 mg/L。实际运行结果表明:主要出水指标COD、BOD5、SS、NH3-N、动植物油的去除率分别可达到97.9%、98.6%、93.7%、93.4%、90.7%。该工艺具有占地少、建设成本低、运行可靠、稳定达标、剩余污泥少、运行成本低、维护简便等优点。     

煤矿矿井乏风瓦斯利用方法浅谈

甲烷是仅次于二氧化碳的重要温室气体,甲烷排入大气而引起气候异常以及对臭氧层的破坏,已经成为全世界共同面临的重大问题。矿井乏风是最大的甲烷工业排放源,收集和利用煤矿乏风瓦斯,减少温室气体排放,是我国面临的紧迫任务。本文根据近几年从事矿井乏风处理项目环评工作经验,对目前煤矿所采用的乏风氧化处理方法进行了探讨,并对乏风处理后带来的环境效益进行了阐述。     

水体中四环素类抗生素的去除技术研究进展

四环素类抗生素因其可以防治人类和动物由病菌引起的疾病,同时又能用作生长促进剂以加快动物生长,目前在国内外被大量使用。抗生素的使用甚至滥用对自然环境造成不容忽视的污染,并进一步对人类身体健康产生潜在危害。从常规处理、膜处理、化学氧化和吸附等角度讨论了国内外对四环素类抗生素去除技术的研究进展,为环境水体中四环素类抗生素污染的有效去除提供了方向。     

几种工业废水可生化性判定指标的验证与评价

测定了几种工业废水的可生化性指标BOD5/COD比值和相对耗氧速率,根据模拟生物氧化塘的动态运行试验结果,提出以耗氧速率(R％)作为可生化性的判定指标,它比BOD5/COD比值测定快速,方法简便,更接近实际,并得出两个指标与生物塘COD去除率之间相关性的线性回归方程,为选择废水生物塘处理方案、预估其对COD的去除效率提供了理论依据。      

氧化塘深度处理焦化废水的初步研究

焦化废水经过常规的二级处理后,ＣＯＤ和ＮＨ３－Ｎ往往难到达到国家排放标准,以活性污泥法处理焦化废水的出水水质为依据,采用氧化塘深度处理焦化废水,其ＣＯＤ和ＮＨ３－Ｎ均可达到国家排放标准。因此,只要只要条件控制得当,运用氧化塘处理低浓度焦化废水可以获得较好处理效果。     

无人监测船在城市内河水质监测中的应用

采用无人船监测技术结合镇江市内河水质状况普查工作,大于120 h的航行试验,总航行里程约为90 km,对建成区水体中的氨氮(NH3-N)、溶解氧(DO)、氧化还原电位(ORP)和浊度进行原位监测,结果表明,通过合理选择搭载相应的测量电极,无人监测船能够满足地表水测量数据准确度的要求,同时可实现研究区域的监测全覆盖,提升了地表水环境监测的工作效率。     

Abiotic oxidation of 17β-estradiol by soil manganese oxides

The degradation of 17β-estradiol (E2) in sterile soil and Mn-free soil slurries was determined. In 0.075 g ml⁻¹ soil slurry, E2 with an initial concentration of 0.0267 μmol g⁻¹ was rapidly degraded and near equimolar estrone (E1) accumulated. A mass balance involving E2 and E1 existed throughout the reaction. The E2 degradation was thus an oxidation process and E1 was the only product. The concurrent release of Mn(II) during E2 oxidation and a lack of E2 oxidation in Mn-free soil slurry together demonstrated that soil manganese oxides were responsible for E2 oxidation. The degree of E2 oxidation was higher at high pH than at low pH, consistent with the fact that the reaction released protons. This study suggests that manganese oxides may be used as soil amendments to effectively oxidize E2 to less potent E1 in soil.     

Oxidation of a PAH polluted soil using modified Fenton reaction in unsaturated condition affects biological and physico-chemical properties

A batch experiment was conducted to assess the impact of chemical oxidation using modified Fenton reaction on PAH content and on physico-chemical and biological parameters of an industrial PAH contaminated soil in unsaturated condition. Two levels of oxidant (H₂O₂, 6 and 65 g kg⁻¹) and FeSO₄ were applied. Agronomic parameters, bacterial and fungal density, microbial activity, seed germination and ryegrass growth were assessed. Partial removal of PAHs (14% and 22%) was obtained with the addition of oxidant. The impact of chemical oxidation on PAH removal and soil physico-chemical and biological parameters differed depending on the level of reagent. The treatment with the highest concentration of oxidant decreased soil pH, cation exchange capacity and extractable phosphorus content. Bacterial, fungal, and PAH degrading bacteria densities were also lower in oxidized soil. However a rebound of microbial populations and an increased microbial activity in oxidized soil were measured after 5 weeks of incubation. Plant growth on soil treated by the highest level of oxidant was negatively affected.