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Alkali wastewater crystallization is a sustainable treatment method that uses cooling, evaporation, or chemical adjustments to transform dissolved inorganic salts (e.g.,

) into solid crystals. It effectively reduces wastewater COD, recovers high-purity salts, and produces clean water, with methods including conventional evaporation, membrane distillation-crystallization, and eutectic freeze crystallization (EFC).

Evaporation and Crystallization: Used to recover valuable products like NaOH and
from alkaline mother solutions, often followed by neutralization and further treatment.
Acidification and Precipitation: Pre-treatment of highly alkaline wastewater (e.g., from nylon-6 production) with sulfuric acid allows for the removal of black slurries and recovery of compounds through subsequent crystallization.
Eutectic Freeze Crystallization (EFC): A highly energy-efficient method (requiring
of the energy of evaporation) that separates water as ice and salts as solid crystals simultaneously at eutectic temperatures.
Membrane Distillation–Crystallization: Utilizes membrane contactors for low-energy separation at lower temperatures (
$is less than 50 raised to the composed with power C$
), ideal for recovering salts from synthetic solutions.

Valuable Salt Recovery: Used to purify industrial wastewater, such as recovering terephthalic acid (up to
purity) from alkali reduction wastewater.
Environmental Protection: Highly effective at removing trace amounts of dissolved impurities.
Operational Benefits: Crystallization reduces operational costs and space requirements compared to traditional waste treatment methods.

Temperature and Solubility: Solubility of salts changes with temperature, making controlled cooling essential for efficient crystal separation.
pH Management: While crystallization reduces pollutants, highly alkaline streams often require pre-treatment acidification with chemicals like
$cap H sub 2 cap S cap O sub 4$
to break down complex compounds.
Impurity Removal: The effectiveness of crystal recovery is dependent on controlling factors like cooling rate and impurities.

Recovery of Terephthalic Acid from Alkali Reduction ...
Sep 8, 2011 — Abstract. A process for the recovery and purification of terephthalic acid (TA) from alkali reduction wastewater is reported. TA w...
Wiley Online Library
Recovery of inorganic compounds from spent alkaline pulping ...
Development of a reliable alkaline wastewater treatment ...
Dec 15, 2005 — Abstract. Alkaline waters produced by caprolactam plants polymerizing the fibres of nylon-6 are characterized by a very high alkal...
ScienceDirect.com

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Web results

Development of a reliable alkaline wastewater treatment ...

ScienceDirect.com

https://www.sciencedirect.com › article › abs › pii

ScienceDirect.com

https://www.sciencedirect.com › article › abs › pii

by M Prisciandaro2005Cited by 28 — Essentially, the process is divided into four stages: acidification step with black mud precipitation, filtrate precipitation, CECS extraction by means of ...Read more

Alkali waste water crystallization

WEIXIAN (Nanjing) Science Technology co., ltd

https://www.njweixian.com › alkali-waste-water-crystalliz...

WEIXIAN (Nanjing) Science Technology co., ltd

https://www.njweixian.com › alkali-waste-water-crystalliz...

Customized Alkali waste water crystallization, please click to get a quote and more information.

The Role of Water- and Alkali-Treated Sisal Leaf Wastewaters ...

PubMed Central (PMC) (.gov)

https://pmc.ncbi.nlm.nih.gov › articles › PMC11313445

PubMed Central (PMC) (.gov)

https://pmc.ncbi.nlm.nih.gov › articles › PMC11313445

by L Li2024 — Alkali-treated plant wastewaters contain complex constituents, including inorganic pollutants, plant nutrients, carbohydrates, and lignin. These ...Read more

Chlor-Alkali

Veolia Water Technologies - North America

https://www.veoliawatertech.com › industries-we-serve

Veolia Water Technologies - North America

https://www.veoliawatertech.com › industries-we-serve

These systems are utilized in brine treatment, brine evaporation, salt crystallization, sodium hydroxide concentration, and inorganic crystal production from ...Read more

High-Salinity Wastewater Crystallization: ZLD Challenges ...

YASA ET

https://www.yasa.ltd › post › high-salinity-wastewater-c...

YASA ET

https://www.yasa.ltd › post › high-salinity-wastewater-c...

Aug 13, 2025 — This article outlines the main challenges in high-salinity wastewater crystallization, supported by real-world case studies, and presents ...Read more

Recovery of Terephthalic Acid from Alkali Reduction ...

Wiley Online Library

https://onlinelibrary.wiley.com › abs › ceat.201100096

Wiley Online Library

https://onlinelibrary.wiley.com › abs › ceat.201100096

by SC Wu2011Cited by 24 — Terephthalic acid (TA) was successfully recovered and purified from alkali reduction wastewater by acidification with sulfuric acid and by ...

Crystallization in Water and Used Water Purification

Springer Nature Link

https://link.springer.com › rwe

Springer Nature Link

https://link.springer.com › rwe

Mar 26, 2024 — Crystallization is a separation process that relies on the solid crystal formation from a solution and removes dissolved salts and other impurities from ...Read more

Missing: ~~Alkali~~ ‎| Show results with: Alkali

Alkaline Wastewater - an overview

ScienceDirect

https://www.sciencedirect.com › topics › engineering › al...

ScienceDirect

https://www.sciencedirect.com › topics › engineering › al...

The wastewater B in Fig. 8.5 is the alkaline wastewater generated in decomposition of monazite concentrate by sodium hydroxide. In Section 1.4.1.7 of Chapter ...Read more

High-purity crystallization and salt-withdrawal process for ...

Google Patents

https://patents.google.com › patent

Google Patents

https://patents.google.com › patent

The process comprises the steps that the high-salinity waste water is subjected to evaporation and concentration through a sodium sulfate crystallization unit, ...Read more

Recovery of inorganic compounds from spent alkaline pulping ...

BioResources

https://bioresources.cnr.ncsu.edu › resources › recovery...