Durham污水处理厂提标改造--新增生污泥厌氧释磷和磷回收

Upgrading and Reconstruction of Durham WWTP in Application of Newly Constructed Raw Sludge Anaerobic Phosphorus Release and Phosphorus Recovery Process

Durham污水处理厂原采用典型的AAO工艺+强化化学除磷和砂滤,并于2002年研制了UFAT技术对初沉池污泥浓缩发酵,促进可挥发性脂肪酸的释放以利用其作为碳源强化生物脱氮除磷,减少外加除磷所需药剂量。为应对磷排放要求的提升,减少污泥厌氧消化系统中鸟粪石累积对管道、设备等的损害,同时降低消化液回流对主体工艺的氮、磷负荷,该厂进行了升级改造。2009年该厂新增Pearl~磷回收工艺生产基于鸟粪石成分的Crystal Green^(TM)化肥产品,并研发配套的WASSTRIP^(TM)工艺强化磷、镁的释放,以进一步减少鸟粪石在污泥系统中的产生和积累,使得污泥中约65%的磷得到固化利用,改善了生物除磷的效果、减少了后端强化化学除磷所需药剂量的40%,同时提高了消化污泥脱水率,据测算可在7年后收回投资成本并产生经济收益。

Durham Advanced Wastewater Treatment Facility （ Durham） was operated as a typical AAO biological treatment processes followed by the enhanced tertiary chemical phosphorus removal and granular media filtration. Starting from 2002, Durham developed Unified Fermentation and Thickening （UFAT） process to promote the volatile fatty acid release from thickened primary sludge helping to improve the biological phosphorus/nitrogen removal performance, thereby reducing the subsequence chemical dosage. To meet the increasingly stringent nutrient removal permit and minimize the negative impact from the anaerobically digested sludge struvite precipitate as well as to whittle down the returned side-stream nutrient load to the liquid stream, Durham initiated another round major upgrading in 2009 and 2011,integrating Peral and WASSTRIP^TM processes to the sludge treatment system, recovering phosphorus and producing struvite based Crystal Green^TM fertilizer product. Through upgrading, total of 65% phosphorus carried in the sludge was removed and utilized （ equivalent to about 80% of influent soluble phosphate）,tertiary chemical dosage was reduced by 40%,and the sludge dewater ability was also improved. Financially, the capital invested was paid back in approximately 7 years.