Production of biodegradable plastics by anaerobic aerobic activated sludge (phosphate accumulating sludge.

以下结论是通过在实验室规模的工厂中培养的厌氧好氧活性污泥或实际工厂污泥中加入各种有机基质或工业废水进行的批量实验得出的。在厌氧条件下，磷酸盐积累污泥能够从乙酸盐、丙酸盐、丙酮酸盐、苹果酸盐、琥珀酸盐和葡萄糖中生产出可生物降解的塑料PHA。磷酸盐积累污泥在好氧条件下比在厌氧条件下产生更多的PHA。在PHA的好氧生产中，更多的空气供应产生更多的PHA。供气量存在一个阈值，超过该阈值后，PHA产量不再随供气量的增加而增加。本研究采用的1升反应器的最佳送风速率为4.5 ml/min。通过送风，污泥的PHA含量根据污泥的初始干重提高到54%，根据污泥的最终干重提高到33%。但要实现PHA.5的商业化生产，可能需要更多的积累。在最佳送风条件下，DO浓度很低且不可控。氧化还原电位（ORP）可作为供气的另一个控制参数。在高底物浓度下观察到PHA产生的抑制作用。存在一个最佳底物浓度。实际植物污泥的特性彼此差异很大，导致不同的最佳送风速率，合适的底物浓度和必要的保留时间。实际污泥积累的PHA少于实验室污泥（污泥干重的15%）。医药生产厂发酵装置的工业废水可用作PHA生产的底物。

The following conclusions were obtained from batch experiments in which anaerobic aerobic activated sludges cultivated in a lab scale plant or practical plant sludges were fed with various organic substrates or an industrial wastewater.1. Phosphate accumulating sludges were capable of producing a biodegradable prastic, PHA, from asetate, propionate, pyruvate, malate, succinate and glucose under anaerobic conditions.2. Phosphate accumulating sludges produce more PHA under aerobic conditions than under anaerobic conditions.3. In the aerobic production of PHA, more PHA is produced with more air supply. There is a threshold value of air supply rate, beyond which the PHA production does not increase any more with the increase of air supply. The optimum air supply rate for the one liter reactor used in the present study was 4.5 ml/min.4. By supplying air, the PHA content of the sludge was raised up to 54% based on initial sludge dry weight and 33% based on final sludge dry weight. But more accumulation may be necessary for commercial production of PHA.5. The DO concentration, when the optimum air supply was achieved, was very low and not controlable. Oxidation-reduction potential(ORP)can be an alternative control parameter for the air supply.6. An inhibition of PHA production was observed at high substrate concentrations. An optimum substrate concentration exists.7. The characteristics of practical plant sludges differ very much from each other, resulting in different optimum air supply rates, suitable substrate concentrations and necessary retention times. Actual sludges accumulated less PHA than lab sludge(15% of sludge dry weight).8. Industrial wastewater from a fermentation unit of a medicine producing factory can be used as substrate for PHA production.