Beauchamp Chantal J, Simao-Beaunoir Anne-Marie, Beaulieu Carole, Chalifour François-Philippe
Département de phytologie, Université Laval, Sainte-Foy, Que., Canada, G1K 7P4.
Water Res. 2006 Jul;40(12):2452-62. doi: 10.1016/j.watres.2006.04.002. Epub 2006 May 22.
Paper sludges are solid wastes material generated from the paper production, which have been characterized for their chemical contents. Some are rich in wood fiber and are a good carbon source, for example the primary and de-inking paper sludges. Others are made rich in nitrogen and phosphorus by pressing the activated sludge, resulting from the biological water treatments, with the primary sludge, yielding the combined paper sludge. Still, in the absence of sanitary effluents very few studies have addressed the characterization of their coliform microflora. Therefore, this study investigated the thermotolerant coliform population of one paper mill effluent and two paper mill sludges and wood chips screening rejects using chromogenic media. For the first series of analyses, the medium used was Colilert broth and positive tubes were selected to isolate bacteria in pure culture on MacConkey agar. In a second series of analyses, double selective media, based on ss-galactosidase and ss-glucuronidase activities, were used to isolate bacteria. First, the presence of thermotolerant coliforms was detected in low numbers in most water effluents, but showed that the entrance of the thermotolerant coliforms was early in the industrial process. Also, large numbers of thermotolerant coliforms, i.e., 7,000,000 MPN/g sludge (dry weight; d.w.), were found in combined sludges. From this first series of isolations, bacteria were purified on MacConkey medium and identified as Citrobacter freundii, Enterobacter sp, E. sakazakii, E. cloacae, Escherichia coli, K. pneumoniae, K. pneumoniae subsp. rhinoscleromatis, K. pneumoniae subsp. ozaenae, K. pneumoniae subsp. pneumoniae, Pantoea sp, Raoultella terrigena, R. planticola. Second, the presence of thermotolerant coliforms was measured at more than 3,700-6,000 MPN/g (d.w) sludge, whereas E. coli was detected from 730 to more than 3,300 MPN/g (d.w.) sludge. The presence of thermotolerant coliform bacteria and E. coli was sometimes detected from wood chips screening rejects in large quantities. Also, indigenous E. coli were able to multiply into the combined sludge, and inoculated E. coli isolates were often able to multiply in wood chips and combined sludge media. In this second series of isolations, API20E and Biolog identified most isolates as E. coli, but others remained unidentified. The sequences of the 16S rDNA confirmed that most isolates were likely E. coli, few Burkholderia spp, but 10% of the isolates remained unidentified. This study points out that the coliform bacteria are introduced by the wood chips in the water effluents, where they can survive throught the primary clarifier and regrow in combined sludges.
造纸污泥是造纸生产过程中产生的固体废物，其化学成分已得到表征。有些富含木纤维，是良好的碳源，例如初级和脱墨造纸污泥。其他的则通过将生物水处理产生的活性污泥与初级污泥压榨，使氮和磷含量增加，从而产生混合造纸污泥。然而，在没有生活污水的情况下，很少有研究涉及对其大肠菌群微生物群落的表征。因此，本研究使用显色培养基对一家造纸厂废水、两种造纸厂污泥以及木片筛选废料中的耐热大肠菌群数量进行了调查。在第一系列分析中，使用的培养基是Colilert肉汤，选择阳性管在麦康凯琼脂上分离纯培养细菌。在第二系列分析中，使用基于β-半乳糖苷酶和β-葡萄糖醛酸酶活性的双重选择培养基分离细菌。首先，在大多数废水样本中检测到少量耐热大肠菌群，但表明耐热大肠菌群在工业过程早期就已进入。此外，在混合污泥中发现了大量耐热大肠菌群，即7,000,000 MPN/g污泥（干重；d.w.）。从这第一系列分离中，细菌在麦康凯培养基上纯化，并鉴定为弗氏柠檬酸杆菌、肠杆菌属、阪崎肠杆菌、阴沟肠杆菌、大肠杆菌、肺炎克雷伯菌、鼻硬结亚种肺炎克雷伯菌、臭鼻亚种肺炎克雷伯菌、肺炎亚种肺炎克雷伯菌、泛菌属、土生拉乌尔菌、植生拉乌尔菌。其次，测得耐热大肠菌群的存在量超过3,700 - 6,000 MPN/g（d.w）污泥，而大肠杆菌的检测量为730至超过3,300 MPN/g（d.w.）污泥。有时在大量木片筛选废料中检测到耐热大肠菌群细菌和大肠杆菌的存在。此外，本地大肠杆菌能够在混合污泥中繁殖，接种的大肠杆菌分离株通常能够在木片和混合污泥培养基中繁殖。在这第二系列分离中，API20E和Biolog将大多数分离株鉴定为大肠杆菌，但其他一些仍未鉴定。16S rDNA序列证实大多数分离株可能是大肠杆菌，少数是伯克霍尔德菌属，但仍有10%的分离株未鉴定。本研究指出，大肠菌群是由木片引入废水的，它们可以在初级澄清池中存活并在混合污泥中重新生长。
