Diagnostic analysis and application of advanced treatment system for reclaimed water in thermal power plant

doi:10.19965/j.cnki.iwt.2022-0200

Abstract

Abstract:

To solve the problems of insufficient output and substandard water quality in the advanced treatment system of reclaimed water in thermal power plant，this paper puts forward the technical improvement of the advanced treatment system of reclaimed water based on the effective combination of “automatic sludge discharge plus sludge homogenization” sludge pretreatment method，active external circulation quantitative activated sludge supply method and “wet” lime dosing method with reflux and double-feed regulation. The system design output is restored after application in a power plant project in north China. The operation results show that turbidity is 0.71 NTU，temporary hardness is 0.65 mmol/L，total hardness is 4.11 mmol/L，temporary hardness removal rate is 84%，and the total hardness removal rate is 32%. The effluent water quality is better than the reuse requirements，saving 2.88 million tons of tap water every year. The advanced treatment system of reclaimed water can greatly reduce the consumption of fresh water，improve the reuse rate of reclaimed water，achieve the purpose of saving water and reducing emissions，and ensure the safety of water supply in thermal power plants.

Key words: reclaimed water, mechanical accelerated clarifier, sludge concentration, automatic sludge discharge, lime dosing

摘要：

为了解决火电厂再生水深度处理系统出力不足、水质不达标等问题，将“自动排泥+污泥均质”污泥预处理方法、主动外循环定量活性污泥供给方法、带回流及双馈调节“湿法”石灰投加方法有效结合，对再生水深度处理系统进行技术改进。并在北方某电厂工程应用，恢复了系统设计出力。运行结果表明，出水浊度为0.71 NTU，暂硬为0.65 mmol/L，总硬度为4.11 mmol/L，暂硬去除率为84%，总硬去除率为32%，出水水质优于回用要求，自来水取水量每年节约288万t。恢复后再生水深度处理系统能够大幅减少新鲜水的取用量，提高再生水重复利用率，达到节水减排的目的，保障火电厂的供水安全。

关键词: 再生水, 机械加速澄清池, 污泥浓度, 自动排泥, 石灰加药

CLC Number:

X773

Shirong MU,Yu ZHOU,Zhian YE,Shaozeng WANG,Shaoxin KANG,Zhaoying XU,Yanfei WANG. Diagnostic analysis and application of advanced treatment system for reclaimed water in thermal power plant[J]. Industrial Water Treatment, 2023, 43(1): 168-174.

慕时荣,周宇,叶治安,王绍曾,康少鑫,徐兆郢,王飞. 火电厂再生水深度处理系统诊断分析与应用[J]. 工业水处理, 2023, 43(1): 168-174.

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URL: https://www.iwt.cn/EN/10.19965/j.cnki.iwt.2022-0200

https://www.iwt.cn/EN/Y2023/V43/I1/168

Figures/Tables 10

Fig. 1 Process flow of advanced treatment system of reclaimed water

Table 1 Design inlet and outlet water quality

项目	设计进水水质	设计出水
pH	7.23（7.54）	7~8.5
浊度/NTU	3.63（4.14）	≤5
COD/（mg·L^-1）	18（45）	≤30
BOD/（mg·L^-1）	5（24）	≤10
氨氮/（mg·L^-1）	0.72（27）	≤10
暂时硬度/（mmol·L^-1）	3.73（4.62）	≤1.3

Fig. 2 Process flow

Fig. 3 Automatic desilting-sludge homogenization system diagram

Fig. 4 Lime preparation dosing system

Fig. 5 Improved process flow

Fig. 6 Turbidity change diagram of effluent water of the system

Fig. 7 Change diagram of system effluent hardness

Fig. 8 Change diagram of sludge density display value of clarifier

Table 2 Benefit analysis

项目	改造前	改造后
药剂费/万元	26.5	320.6
电费/万元	52.7	30.2
泥饼处置费/万元	—	96
取水费/万元	2 438.4	940.8
吨水成本/元	4.01	2.21

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