Zhangjiagang Daxin Town Tap Water Project

The original water purification process of the water supply station of Daxin Town Woolen Textile Factory is: coagulation → sedimentation → sand filtration → water supply. Due to the small water yield and unstable water quality, the post transformation process is: half way coagulation → Ceramic membrane filtration → water supply. After the renovation, the water treatment capacity of the water supply station has been improved, the amount of chemicals has been saved, the area of structures has been greatly reduced, and the effluent quality has been stable and meets the standard. The main indicators of effluent are superior to the standard limits specified in the "Sanitary Standards for Drinking Water" (GB 5749-2022), "Key Water Quality Indicator Control Standards for Urban Waterworks in Jiangsu Province" (DB32/T 3701-2019), and "Limits for Drinking Water Quality Indicators in Suzhou City" (Su Shi Shui Wu [2021] No. 376).

Limit values of water quality indicators for domestic drinking water in Suzhou City

Project	Limit values of water quality indicators for domestic drinking water in Suzhou City	Effluent quality of water supply station
CFU/mL	50	Not detected
MPN/100mL、CFU/mL	Not detectable	Not detected
Platinum cobalt colorimetric unit	10	＜5
Scattering turbidity unit /（NTU）	0.5	＜0.1
Smell and taste	No odor or odor	No odor or odor
Visible to the naked eye	No	No
Permanganate index (calculated by O2)/(mg/L)	Water source limit: 1.5, with the Yangtze River as the water source	1.04
Free chlorine (using chlorine gas and free chlorine) Determination during preparation）	The limit value of factory water and pipe network end water/(mg/L) ≤ 1.0; Water surplus in the pipeline network and at the end of the official website: ≥ 0.05;	0.7
Aluminium（mg/L）	0.15	0.015
Cutter（mg/L）	0.2	＜0.03
Manganese（mg/L）	0.05	＜0.03
Nitrite /（mg/L）	0.1（Free chlorine disinfection）	＜0.001