【作者】 王珏；

【导师】 程翔； 陈珺；

【作者基本信息】 北京林业大学 ， 工程硕士（专业学位）， 2016， 硕士

【摘要】 磷酸盐在工、农业生产中有着不可替代的作用,但磷在自然界的流动在较短的时间基本上是单向的,如何保护和利用有限的磷资源是各国政府和学者研究的重要课题。城市污水中磷浓度可达6-23mg/L,其去除与回收具有十分重要的现实意义。蓝铁石结晶的污水/污泥磷回收(Phosphorus Recovery via Vivianite Crystallization,简称PRVC)技术,通过在厌氧污泥消化系统内投加Fe,促成Fe3(PO4)2·8H2O的结晶沉淀,从而达到磷去除和回收的目的。该技术无需新增污水/污泥处理设施,获得的蓝铁石产品价值可远超投加的低品质Fe(Ⅲ),因此具有十分广阔的应用前景。本论文通过搭建包括连续流A2/O单元与含铁运行污泥厌氧消化单元的PRVC型污水生物处理工艺系统,研究了投加Fe(Ⅲ)在污泥厌氧消化系统中的还原作用,及其对污泥厌氧发酵过程和产甲烷的作用；考察了含铁消化液回流至生物主体处理系统后,Fe在A2/O主体处理系统各单元中的形态与分布及其对主体处理系统COD降解与脱氮除磷效率的影响。得到主要结论如下：(1)投加FeOOH至厌氧消化系统后,大部分Fe以0.5M HCl不可提取Fe的形式存在,除一部分为污泥微生物结合态,主要去向可能为Fe(Ⅱ)的沉淀物,而液相的Fe以溶解态Fe(Ⅱ)为主。含铁消化液回流至A2/O主体处理系统,系统各单元中的Fe主要以溶解态的形式存在,厌氧池和缺氧池以Fe(Ⅱ)的形式为主,好氧池中的Fe主要为Fe(Ⅲ)。(2)投加Fe(Ⅲ)对污泥厌氧消化体系的产酸发酵过程有一定的促进作用,对产甲烷菌有轻微的抑制作用。总体上看,Fe(Ⅲ)的厌氧还原促进了厌氧消化过程中污泥有机质的降解。消化池含铁上清液回流至主体处理系统后,由于污泥生物量的增加,污水COD去除略有加强。(3)污泥消化系统中Fe(Ⅲ)的投加及其还原可使系统的除磷效率提高35.1%,在污泥表面观察到有类似蓝铁石Fe3(PO4)·8H2O的结晶产物生成。消化池含铁上清液回流后,生物主体处理系统的除磷效率亦有所提高。Fe(Ⅱ)可作为电子供体促进了缺氧池的反硝化作用,整体系统总氮去除率升高了15.9%。(4)投加FeOOH可有效改善消化污泥脱水性能,含Fe运行时消化污泥比阻下降86.2%。消化池含铁上清液回流至生物主体处理系统后,各池污泥的浓度上升11.86%,沉降性能也有小幅提高。更多还原

【Abstract】 Phosphate plays an irreplaceable role in industrial and agricultural production, whereas phosphorus flow in nature for a short term is basically not a cycle. How to protect and better utilize the resource of phosphorus becomes an important issue for the governments and researchers across the world. Urban sewage contains 6-23 mg/L of phosphorus, therefore its removal and recovery is of great significance from both environmental and resource aspects. Phosphorus recovery via vivianite crystallization (PRVC) was developed to remove and recover phosphorus by adding Fe to the anaerobic sludge digester and promoting crystallization of vivianite, Fe3(PO4)2·8H2O. This technology does not require extra sewage/sludge treatment facilities, and the recovered vivianite has a much higher value than the dosed low-quality Fe(Ⅲ), therefore becomes a promising alternative for enhanced phosphorus removal and recovery in the future.This study established a PRVC-type sewage treatment system consisting of continuous flow anaerobic-anoxic-aerobic units and an iron-amended anaerobic digester. We investigated (1) the reduction of the dosed Fe(Ⅲ) in the anaerobic sludge digester and its influence on the sludge fermentation and the followed methanogenis, (2) the speciation of Fe in the A2/O tanks via the return of sludge digestion supernatant and the influence on the removal of COD, N and phosphorus. The major conclusions obtained include:(1) After dosing FeOOH to the anaerobic sludge digester, a big fraction of Fe was in the form of 0.5M HCl non-extractable Fe. Except a small amount of Fe being combined with the sludge microbes, the majority was probably as Fe(Ⅱ) precipitates. In the liquid phase, most of Fe was aqueous Fe(Ⅱ). When the Fe containing digestion supernant was returned to the A2/O biotreatment system, the Fe was mostly aqueous as Fe(Ⅱ) in the anaerobic tank and anoxic and as Fe(Ⅲ) in the aerobic tank.(2) Fe(Ⅲ) dosing to the anaerobic digester stimulated the fermentation of sludge biomass, while had a slight inhibition on the methanogenesis. Generally, the reduction of Fe(Ⅲ) promoted the degradation of the sludge organics. The return of Fe-containing sludge digestion supernatant increased the level of suspended solids in the A2/O tanks, and enhanced the removal of COD to a small extent.(3) The dosing of Fe(III) increased the efficiency of phosphorus removal in the anaerobic sludge digester by 35.1%. Some vivianite-like crystals were observed on the sludge surface. The return of Fe containing digestion supernatant increased marginally the removal of phosphorus by the A2/O system. Because Fe(II) can be an electron donor for the denitrification in the anoxic tank, the efficiency of total N removal was increased by 15.9%.(4) The addition of FeOOH effectively improved the dewatering property of the digested sludge; the specific resistance was reduced by 86.2%. The returned Fe to the A2/O system increased the sludge concentration by 11.86% and the settleing ability was slightly inproved.更多还原