Source:
(1) The four processes of printing and dyeing processing (pretreatment, dyeing, printing, and finishing) all discharge wastewater.
(2) The pretreatment stage includes processes such as singeing, desizing, boiling, bleaching, and silk polishing. The wastewater generated includes desizing wastewater, boiling wastewater, bleaching wastewater, and silk polishing wastewater.
(3) The dyeing process generates dyeing wastewater, the printing process generates printing wastewater and soap solution wastewater, and the finishing process discharges finishing wastewater.
The main related industries involved are: printing and dyeing factories, wool dyeing and finishing factories, silk factories, clothing manufacturing, home textile manufacturing, etc.
Characteristic:
(1) Large water volume: 100-200 tons of water are consumed per ton of textile printing and dyeing processing, of which 80% -90% are discharged as wastewater.
(2) High content of organic pollutants: Wastewater contains dyes, slurries, additives, oils, acids and bases, fiber impurities, sand like substances, inorganic salts, etc.
(3) High alkalinity: The pH value is relatively high, and some wastewater can reach a pH value of 12 or above.
(4) Significant changes in water quality: Depending on the type of fiber and processing technology, there are significant differences in wastewater quality.
1. Physical method:
① Adsorption method: using porous materials such as activated carbon to adsorb pollutants in wastewater. Activated carbon has good adsorption effect, but the cost is relatively high. Can be combined with other processing methods to improve processing efficiency.
② Coagulation method: using coagulants (such as Polyaluminum chloride PAC) to coagulate suspended solids, colloids, etc. in wastewater into larger particles for easy precipitation and removal. PAC has the characteristics of high efficiency, speed, and strong adaptability, and is a commonly used coagulant in the treatment of printing and dyeing wastewater.
③ Filtration method: Remove suspended solids and colloids from wastewater through filter media such as sand filtration and activated carbon filtration. During the filtration process, PAM can be added as a coagulant aid to enhance the coagulation effect of particles and improve filtration efficiency.
2. Chemical method:
① Ozone oxidation method, photooxidation method, etc.: use strong oxidizing substances to remove organic pollutants from wastewater. Although these methods have good treatment effects, they are costly and suitable for situations that require high effluent quality.
② Coagulation precipitation method: By adding coagulants (such as PAC) and coagulants (such as PAM), pollutants in wastewater are coagulated into precipitates, which are then removed. This method has low cost and is suitable for large-scale wastewater treatment.
3. Biological method:
Aerobic biological treatment method: utilizing the metabolic activity of aerobic microorganisms to remove organic pollutants from wastewater.
Anaerobic biological treatment method: using the metabolic process of anaerobic microorganisms under anaerobic conditions to remove organic pollutants from wastewater.
Biofilm method: using microorganisms attached to a carrier to remove organic pollutants from wastewater.
Case Name:
Wastewater Treatment Project of a Printing and Dyeing Enterprise in Zhejiang Province
Project Overview:
Wastewater mainly contains pulp, dyes, additives, surfactants, etc.
Wastewater is alkaline, with high COD and chromaticity, and poor biodegradability.
Inlet water quality: COD ≤ 2160, BOD ≤ 613, SS ≤ 310, chromaticity ≤ 560, ammonia nitrogen ≤ 38.
Daily processing capacity: 1000 tons/day.
Processing technology:
Adopting the hydrolysis acidification A/O-BAF combination process for treatment, while adding PAC as a coagulant and PAM as a coagulant aid to improve the coagulation and sedimentation effect. The treated water quality meets the first level standard of GB4287-1992 "Emission Standards for Water Pollutants in Textile Dyeing and Finishing Industry", and the actual effluent quality is better than the standard value.
Processing effect:
Meet the first level standards of GB4287-1992 "Emission Standards for Water Pollutants in Textile Dyeing and Finishing Industry": COD ≤ 100, BOD ≤ 25, SS ≤ 70, chromaticity ≤ 40, ammonia nitrogen ≤ 15.
Actual effluent quality: COD ≤ 65, BOD ≤ 20, SS ≤ 15, chromaticity ≤ 35, ammonia nitrogen ≤ 10
In summary, the treatment of printing and dyeing wastewater requires comprehensive consideration of the source, characteristics, and treatment requirements of the wastewater, and the selection of appropriate treatment methods.
The Polyaluminum chloride(PAC) and Polyacrylamide(PAM) products produced by Yuxinhuan play an important role as commonly used water treatment agents in the treatment of printing and dyeing wastewater, effectively improving treatment efficiency, reducing treatment costs, and protecting the environment and water resources.