市政污泥超高压滤脱水-微波/热风协同干化技术与机理研究

As the rapid development of economic and urbanization, the output of municipal sludge increases greatly. Due to the difficulty in dewatering, high moisture content, high energy consumption and low drying efficiency of municipal sludge, a large amount of improperly treated sludge become a worldwide social and environmental issue. .Therefore, this project aims to systematically investigate the technology and mechanisms of municipal sludge dewatering with ultrahigh pressure filtration and microwave/hot-air synergistic drying. The thread running through this proposal is the filtration-drying coupling technology..The following key scientific problems such as variation characteristics of drain-channel and microscopic clogging mechanisms, effect of moisture distribution on the lowest moisture content under extreme dynamics conditions, moisture migration and driving force identification in synergetic drying etc are explored based on synthetical methods including experimental research, microscopic analysis, theoretical derivation, modeling and validation, parameter optimization etc..The objective of this project is to develop physical and mathematical models for drain-channel variation and granular clogging, reveal the dewatering microscopic mechanisms, determine the relationship between the limitation of mechanical pressure filtration dewatering and fractionation of removed moisture, illustrate the synergistic-drying mechanisms. .It is expected that the current project can develop a coupling technique with energy efficient based on ultrahigh pressure filtration dewatering and microwave/hot-air synergistic drying in order to solve the common problems of municipal sludge and promote the development of sludge treatment and disposal.

随着经济发展及城市化进程加快，城市污水处理厂伴生的污泥产量快速增长。市政污泥存在脱水困难、含水率高、干化效率低、能耗高等问题，导致大量污泥没有得到妥善处置，成为一个世界性的社会和环境问题。本项目以市政污泥超高压滤脱水-微波/热风协同干化技术与机理为研究目标，以污泥脱水-干化耦合处理工艺为主线，采用实验研究、微观分析、理论推导、建模及验证、参数优化等综合研究方法，系统研究脱水过程中的排水通道变化规律及淤堵微观机理、极端力学条件下的水分分布对最低含水率影响关系、协同干化水分迁移规律及推动力识别等关键科学问题。建立污泥排水通道变化及淤堵物理及数学模型，揭示污泥脱水微观机理，明确极端力学条件下压滤脱水极限效果与所能去除的水分形态关系，阐明协同干化机制，形成低能耗超高压滤脱水-微波/热风协同干化技术，解决市政污泥的共性难题，推动污泥处理处置发展。

城市污水处理厂伴生的污泥产量快速增长，市政污泥存在脱水困难、含水率高、干化效率低、能耗高等问题，大量的市政污泥已成为世界性的环境问题。.本项目以市政污泥超高压滤脱水-微波/热风协同干化机理与技术为研究目标，系统研究了影响污泥机械压滤脱水效果的主要因素、各种调理方法的污泥脱水效果，脱水过程中排水通道变化规律及淤堵机理、污泥水分形态分布、极端力学条件下最低含水率、压滤过程泥饼内部应力分布，机械压滤电渗透耦合脱水机理及方法，热风-微波协同干化系统的设计、干化主要影响因素、干化过程水分迁移规律及推动力识别等内容。.结果表明：压榨压力、脱水时间、泥饼厚度、污泥性质对脱水效果都具有重要影响，微波、冻融调理等可以改善污泥脱水效果；在超高压薄层长时间压榨作用下，污泥含水率可降至35%以下；压滤过程污泥孔隙逐渐减小甚至堵塞，市政污泥孔径分布具有分形自相似性，孔径集中分布于0.4-4um，泥饼水分呈现分层现象，内部水分比表层水分高达25%以上，由于毛细现象、内部非连通孔隙、内部结合水等因素使得机械压滤存在一定脱水极限，泥饼内部压力存在中间低两头高的分布。电渗透机械压滤耦合可显著改善污泥水分形态变化、孔隙结构以及脱水效果、脱水时间等，但是需要考虑能耗问题。污泥堆层、风速、温度、微波参数等对干化效果具有明显影响，在热风的干化基础上增加微波协同作用后，扩散系数值变大，在微波协同作用干化过程中水分扩散速率比单独热风作用提高了1.4倍。机械脱水-热干化组合具有低能耗高效率的效果，在机械压滤将污泥含水率降至较低含水率下再热风干化，具有处理效率及能耗两者平衡的综合优势。.本项目建立了污泥排水通道变化及淤堵物理及数学模型，揭示了污泥脱水微观机理，明确了极端力学条件下压滤脱水极限效果与所能去除的水分形态关系，阐明了协同干化机制，形成了低能耗超高压滤脱水-微波/热风协同干化技术，对于解决市政污泥的共性难题，推动污泥处理处置发展具有重要意义。