基于湿化学技术从污泥焚烧灰中回收磷的研究进展

Research progress on phosphorus recovery from incinerated sewagesludge ash based on wet-chemical techniques

作为植物生长的必需营养元素之一,磷在现代农业的发展中发挥着不可忽视的作用,并且需求量巨大。由于全球的磷储量有限且磷资源不可再生,污泥焚烧灰因其中磷含量较高且年产量巨大被认为是一种潜在的二次磷资源。本文综述了基于湿化学技术从污泥焚烧灰中回收磷的研究现状,该技术主要包括磷提取过程及后续的磷产品生产过程。磷提取过程主要包括基于酸性试剂的酸提取技术,基于碱性试剂的碱提取技术以及多种方式组合的连续提取技术。磷产品生产过程主要通过化学沉淀和晶体沉淀的方法从富磷溶液中生产磷产品,一般为钙磷、鸟粪石以及蓝铁矿,这三种磷产品都可以作为磷肥促进植物生长。基于湿化学技术从污泥焚烧灰中回收磷产品的难点是其中富集有大量的重金属等杂质元素,因此需要通过各种纯化预处理手段降低溶液中的杂质含量,以提高后续回收的磷产品纯度。本文总结了基于湿化学技术的各种纯化预处理手段,主要包括离子交换除杂技术,磷吸附-解吸附技术,以及通过控制pH的沉淀除杂技术等。本文探讨了从污泥焚烧灰中回收磷产品的可行性及必要性,总结了基于湿化学技术从其中回收磷产品的方法及技术路线,分析了湿化学技术回收污泥焚烧灰中磷产品的基本原理,为开发新的从其中回收磷的技术提供了参考。

As one of the essential nutrients for plant growth,phosphorus plays an indispensable role in the development of modern agriculture and is in great demand.Since global phosphorus reserves are limited and phosphorus resources are not renewable,incinerated sewage sludge ash(ISSA)is considered to be a potential secondary phosphorus resource due to its high phosphorus content and huge annual production.The paper summarizes the current status of research on the recovery of phosphorus from ISSA based on wet-chemical technology,which mainly includes the phosphorus extraction process and the subsequent production process of phosphorus products.The phosphorus extraction process mainly involves acid extraction using acidic reagents,alkaline extraction based on alkaline reagents,and continuous extraction with a combination of various methods.The phosphorus production process primarily yields phosphorus products from phosphorus-rich solutions by means of chemical precipitation and crystal precipitation,generally yielding calcium phosphorus(Ca-P),struvite(MgNH_(4)PO_(4)·6H_(2)O)and vivianite(Fe_(3)(PO_(4))_(2)·8H_(2)O),all of which can be used as phosphorus fertilizers to promote plant growth.The difficulty of recovering phosphorus products from ISSA based on wet-chemical technology is that sludge incineration ash is enriched with a large number of heavy metals and other impurity elements,and it is necessary to reduce the content of impurities in the solution through various purification pretreatment means,so as to improve the purity of the subsequently recovered phosphorus products.In this paper,various purification pretreatment means based on wet-chemical technology are reviewed,mainly including ion exchange impurity removal technology(CER),phosphorus adsorption-desorption technology,and precipitation impurity removal technology through pH control.In conclusion,this paper discusses the feasibility and necessity of recovering phosphorus products from ISSA,summarizing the methods and technical routes of recovering phosphorus products from ISSA based on wet-chemical technology,revealing the basic principles of recovering phosphorus products from ISSA using wet-chemical technology,and providing technical references for developing new technologies for recovering phosphorus from ISSA.