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

通过对实验室规模的厌氧好氧活性污泥或实际工厂污泥进行分批实验，获得了以下结论.在厌氧条件下，聚磷污泥能够利用乙酸、丙酸、丙酮酸、苹果酸、琥珀酸和葡萄糖产生可生物降解的植物脂PHA.聚磷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，随着空气供应量的增加，产生更多的PHA。供气量存在一个阈值，超过该阈值，PHA产量不再随供气量的增加而增加。本研究中使用的一升反应器的最佳空气供应速率为4.5 ml/min。通过供应空气，污泥的PHA含量基于初始污泥干重提高到54%，基于最终污泥干重提高到33%。但更多的积累可能是必要的PHA.5的商业生产。当达到最佳空气供应时，DO浓度非常低且不可控制。氧化还原电位（ORP）可以作为空气供应的替代控制参数。在高底物浓度下观察到PHA产生的抑制。存在一个最佳底物浓度.实际工厂污泥的特性差异很大，导致不同的最佳供气速率，合适的基质浓度和必要的停留时间。实际污泥积累的PHA比实验室污泥少（污泥干重的15%）。来自制药厂的发酵单元的工业废水可用作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.