PHA validation data

An ion chromatographic method for measuring polyhydroxyalkanoate (PHA) in the form of its monomers (R)-3-hydroxybutyrate (3HB) and (R)-3-hydroxyvalerate (3HV) in wastewater was optimized and used to evaluate the PHA content of cells sampled from the aeration basin of a municipal wastewater treatment facility. This is a safer alternative to the more popular gas chromatographic (GC) method. This updated method offers a more sensitive calibration range, improved by two orders of magnitude from 1-16 mg/L to 0.05-5.0 mg/L. Relative standard deviation was reduced from 2% for total PHA in the original method to 0.5% for 3HB and 0.7% for 3HV using the updated protocol. Elution time also was reduced by 20% from 31 minutes to 25 minutes. A relationship was established between sample solids content and PHA extraction efficiency in order to avoid error from incomplete PHA extraction from high solids samples, expanding the application of this method to activated sludge processes with high mixed-liquor suspended solids. Application-based method validation was accomplished using three approaches: (1) commercially available standards, (2) basin profiles of PHA dynamics in a full-scale activated sludge basin, and (3) batch enrichment experiments comparing PHA production dynamics. The results of these three approaches were consistent with published literature. Basin profiles yielded data that reflected expected PHA dynamics in an A2O basin, with intracellular PHA highest just after VFA uptake then decreasing through the aerobic zone. PHA enrichment experiments using activated sludge batch reactors fed with acetate, propionate, and 50/50 mixed-feed showed highly variable PHA yield and monomer distribution. In order of relative total PHA yield from lowest to highest, propionate fed batch reactors produced the least total PHA (17% 3HB, 83% 3HV), mixed VFA fed reactors produced more PHA (69% 3HB, 31% 3HV), and acetate fed bioreactors yielded the highest total PHA (78% 3HB, 22% 3HV). Varying doses of acetate resulted in consistent VFA conversion to PHA regardless of concentration. Comparison of PHA production from basins with differing carbon loading showed that 82% of VFA as COD was converted to PHA from sludge from carbon-poor basins, while 45% of VFA as COD was transformed into PHA in sludge from historically carbon-rich basins. These results validate this updated method as a sensitive and accurate method for measuring PHA in wastewater.

针对废水中的聚羟基脂肪酸酯（PHA）单体（R）-3-羟基丁酸（3HB）和（R）-3-羟基戊酸（3HV）的测定，本研究优化了一种离子色谱法，并运用此法评估了取自市政污水处理设施曝气池的细胞中的PHA含量。相较于更为流行的气相色谱（GC）法，该方法更安全。该更新后的方法提供了一种更宽的灵敏度校准范围，其灵敏度提高了两个数量级，由1-16 mg/L扩展至0.05-5.0 mg/L。通过采用更新的方案，相对标准偏差从原始方法中总PHA的2%降至3HB的0.5%和3HV的0.7%。洗脱时间也从31分钟缩短至25分钟。建立了样品固体含量与PHA提取效率之间的关系，以避免因固体样品中PHA提取不完全而产生的误差，从而扩展了该方法在含有高混合液悬浮固体的活性污泥处理过程中的应用。通过三种方法实现了基于应用的方法验证：(1) 商业标准品；(2) 全尺寸活性污泥池中PHA动态变化的池形分析；(3) 比较PHA生产动态的批次富集实验。这三种方法的结果与已发表的文献一致。池形分析得到的数据反映了A2O池中预期的PHA动态变化，细胞内PHA含量在VFA吸收后最高，随后在好氧区逐渐降低。使用乙酸、丙酸和50/50混合饲料喂养的活性污泥批次反应器进行的PHA富集实验显示了高度可变的PHA产量和单体分布。按相对总PHA产量从低到高的顺序，丙酸喂养的批次反应器产生的总PHA最少（17% 3HB，83% 3HV），混合VFA喂养的反应器产生的PHA更多（69% 3HB，31% 3HV），而乙酸喂养的生物反应器产生的总PHA最高（78% 3HB，22% 3HV）。不同剂量的乙酸导致VFA转化成PHA的效率保持一致，不受浓度影响。比较不同碳负荷的池子中PHA的生产，碳贫池的污泥中82%的VFA（以化学需氧量COD计）转化为PHA，而碳富池的污泥中45%的VFA（以COD计）转化为PHA。这些结果验证了该更新方法作为测量废水中PHA的灵敏且准确的方法。