【作者】 邓毅；

【导师】 陈志强；

【作者基本信息】 哈尔滨工业大学 ， 市政工程， 2012， 硕士

【摘要】 聚羟基烷酸脂（Polyhydroxyalkanoates，简称PHAs或PHA）可以由PHA产生菌利用有机废物水解发酵液进行合成，由于良好的生物可降解性及可再生性,是一类有望代替传统石化塑料的新型生物塑料。但是传统PHA纯菌合成过程中较高的原料、消毒以及微生物分离纯化成本，使得PHA的生产成本一直居高不下，对其产业化应用产生了严重的阻碍作用。而二十世纪九十年代所兴起的PHA混菌合成技术由于其操作简单、无需灭菌，在采用了低廉成本底物的同时对废水中的废弃碳源物质进行了有效的回收利用。混合菌群利用废弃碳源合成聚羟基烷酸酯的工艺，在解决废弃污染物对环境的污染问题的同时，获得了高价值的生物塑料PHA产品，对降低其生产成本、促进其大规模生产与应用具有极其重要的意义。三段式PHA混菌合成工艺是近期研究中被广为采用的一种PHA生产模式，包括废碳源的水解酸化、产PHA菌的定向富集以及PHA的合成三大步。而PHA产生菌的定向富集直接决定了后期PHA合成步骤的合成效率以及工艺成本，是三段式工艺中至关重要的一个环节。如何控制富集期中易于出现的污泥膨胀问题，优化富集菌群提取时机，为PHA合成阶段提供稳定高效的菌源，是该工艺实际应用所面临的最关键的一个难题。本实验基于以蔗糖产酸废水为底物的PHA三段式生产工艺，采用蔗糖产酸废水作为底物，考察了不同进水底物浓度与不同生活污水掺混比对SBR富集反应器启动期污泥稳定性及PHA合成效率影响，以及连续流富集反应器启动期污泥沉降性能与PHA合成能力的变化规律。实验结果发现，在以SBR作为产PHA菌富集反应器时，不同进水底物浓度与不同生活污水掺混比均能对产PHA菌富集反应器启动期污泥稳定性及PHA合成效率造成一定程度的影响，其中掺混10%生活污水的产PHA菌富集反应器的污泥稳定性优于不掺混及掺混20%生活污水，但这一改变对启动期污泥沉降性的改善十分有限，仍未能最终避免污泥膨胀的出现；而不同的进水底物浓度则对微生物菌群的稳定性产生了较大影响。长期实验证实，适中的进水底物浓度（约1100mgCOD/L）能够在较低的污泥龄条件下（SRT=1天）长期维持较高的污泥浓度稳定运行（MLSS≈3000mg/L），同时又具有令人满意的PHA富集效果，其在运行第94天批次试验中分别达到了0.7145PHA COD/底物COD的PHA转化率以及0.1912mg COD PHA/mg X/h的PHA比合成速率。与此同时，我们证实了连续流富集反应器不能够解决启动期出现的污泥膨胀问题，而在出现污泥沉降性恶化时亦无法便利的采取补救措施，故不宜作为最佳的富集反应器形式使用。此外，我们证实了细胞内糖原水平与其PHA合成能力呈正比，在富集过程中可将糖原作为富集效果的指示指标，并为第三阶段选择最佳的种泥提取时机。更多还原

【Abstract】 Polyhydroxyalkanoates (referred to as PHAs or PHA) are a sort of bio-degrable andbio-renewable biological plastics, which was expected to take the place of traditionalpetrochemical-based plastics. Generally, it can be synthetized with PHA producingbacterias using Hydrolysis fermented liquid from organic waste. However, as for thehigh cost of substrate sterilization as well as microbal isolation and purificationoccurred during PHA production process, it was not easy to reduce the high cost of PHAproduct, which hindered it from mass application. The introduction of mixced microbalcultures(MMCs) in PHA production makes it possible for perfect cost control. In thiskind of new process, it owned an simple operation instruction and substrate sterilizationwas no longer needed, thus substrate cost was reduced while renewable carbon source inthe waste watwe was recorved. Thanks to this new technique, the environmental threatof abandoned pollutant was removed and high-value biological plastic PHA productswas obtained, which has a great significance to its cost reduction and vast application.3-stage MMC based PHA production process is widely adopped in recentresearches.It contains3main steps of acidogic of waste carbon source, culture selectionof MMCs and PHA accumulation. Of all the3steps, culture selection is the decisivestep as it will directly affect the synthetic efficiency and process cost in PHA production.To come up with a solution of sludge bulking occurred in step2and optimize cultureextraction time in order to provide stedy and efficient MMCs for PHA production iscritical problem needed to cope with.This research is based on typical3-stage PHA production process using acidogicsugar cane as substrate. We took out a series of experiments to investgate therelationship within organic loading, sanitary sewage feeding, sludge stability and enrichefficiency. Otherwise, we introduced a set of continuous flow reactor to test itslong-term slection efficiency and working stability as enrichment reactor.Test result showed that when SBR was used as enrichment reactor, different influentsubstrate concentration and sanitary sewage addition radio could make a difference tosludge stability and slection efficiency during reactor setup. It was showed that organicfeeding mixed with10%of sanitary sewage had a better performance on sludge stabilitythan organic feeding mixed with20%of sanitary sewage and organic feeding mixedwith no sanitary sewage. However, this advantage was not so obvious as the sludgebulked in the end. On the other hand, influent substrate concentration had a greaterinfluence on sludge stability. Long-term observation showed that medium influent substrate concentration（of about1100mgCOD/L）could maintain a high MLSS(ofabout3000mg/L) under low SRT (SRT=10d) as well as high culture selection efficiency.During batch experiment conducted on the94thday of enrichment, a PHA conversionrate of0.7145COD/COD as well as PHA synthesis rate of0.1912mg COD PHA/mgX/h was achieved. By the way, we proved that the continuous flow reactor will not helpto improve sludge settlebality, and it was not as flexable as SBR once sludge bulkingoccurred. As a consequence, it is not wise of us to choose continuous flow reactor asenrichment reactor. At last, we proved that intracellular glycogen level had a similartrend with its PHA synthesis ability. So we can use glycogen level to indicate cultureselection efficiency in enrichment step, and optimize the timing to introduce PHAsynthesis.更多还原