From Developing To Developed Countries: Why Industrial Development Drives The Upgrading of Water Treatment Technologies

The More Advanced the Industry, the More Important Water Treatment Is — A Symbiotic History of Water and IndustryIndustrial development is not a water crisis, but an era opportunity for the water treatment industry. In the process of developing countries moving towards industrialization, industrial water consumption often grows exponentially, becoming a "hard-hit area" where water resources are in short supply. Faced with the increasingly severe rigid constraints on water resources, the state has forced the industrial sector to shift from extensive water use to refined management through strong policy regulation, spawning a modern water treatment technology system centered on water recycling, reclaimed water reuse and zero discharge, and ultimately achieving a dynamic balance between industrial development and water resource protection.

Industry is an important pillar of the national economy and also a major water consumer. In the initial stage of rapid development in developing countries, industrial water consumption often accounts for a large proportion of the total social water consumption. Taking China as an example, the national industrial water consumption reached 97.02 billion cubic meters in 2023, accounting for about 16.4% of the total water consumption. Water-intensive industries such as iron and steel, petrochemicals and textiles are highly dependent on fresh water resources in the process of expansion, leading to acute contradictions between supply and demand of water resources in some areas, and even ecological crises such as over-extraction of groundwater and river cutoff.

Faced with the shortage of water resources and ecological red lines, the state implements intensity control, efficiency priority, classified management and stepped water prices for industrial water use, with clear requirements:

1. Strictly control new water intake, and give priority to the use of unconventional water sources such as reclaimed water, mine water and rainwater.

2. Promote circulating cooling water systems, series water use systems and condensate recovery to improve the reuse rate of industrial water.

3. Mandatorily construct sewage treatment stations, reclaimed water reuse facilities and concentrated water treatment devices, and advance the advanced treatment, classified reuse and resource utilization of wastewater.

4. Implement cleaner production, energy conservation and consumption reduction, and pollution and carbon reduction in key industries, and upgrade to near zero discharge and zero liquid discharge (ZLD).

This policy orientation of "determining production based on water availability" forces enterprises to take water conservation and emission reduction as a prerequisite for survival and development. After developing countries enter the accelerated stage of industrialization, water-intensive industries such as iron and steel, chemical engineering, electric power, papermaking, printing and dyeing, petrochemicals and electroplating are concentratedly launched. Industrial production of cooling water, process water, boiler water and washing water have all risen across the board, and a large number of enterprises operate in a linear mode of "water intake - use - direct discharge". Industrial wastewater is directly discharged into water bodies without effective treatment, causing excessive pollutants such as COD, ammonia nitrogen, total phosphorus, heavy metals and volatile phenol, and triggering systemic water crises such as river basin pollution, over-extraction of groundwater, seawater intrusion and water shortage due to water quality.

When water resources change from "unlimited supply" to "rigid constraints", the state will inevitably shift from "encouraging water intake" to "total quantity control, quota management, water use permission and pollutant discharge permission", forcing industrial water conservation and pollution control through administrative and legal means, which has become a key turning point for the water treatment industry to move from the edge to the mainstream. Driven by both policies and the market, the water treatment industry has witnessed explosive growth, and its technical path has upgraded from simple "discharge up to standard" to "resource recycling".

Enterprises realize centralized control, intelligent coordination and refined management of the on-site water system by building a water system central control center. Reclaimed water reuse technology uses treated wastewater for non-potable links such as cooling, greening and flushing, effectively replacing fresh water resources. Domestic sewage and rainwater are treated as reclaimed water for cooling water and leachate treatment systems, realizing the resource utilization of wastewater.

Traditional biochemical methods are difficult to treat high-salt wastewater generated by industries such as chemical engineering and electric power. Modern water treatment technology adopts a combined process of "membrane separation + evaporation and crystallization" to achieve "zero discharge" of wastewater. Advanced concentration of wastewater is carried out through membrane technologies such as reverse osmosis (RO), nanofiltration (NF) and ultrafiltration (UF), and then the concentrated brine is evaporated and crystallized through MVR evaporators or multi-effect evaporation devices, finally producing industrial salt and realizing closed-loop management of water resources. This technology not only solves the pollution problem, but also realizes the recovery of salt resources, turning "waste into wealth".

So how does water treatment technology achieve "zero discharge" of wastewater?

Membrane separation technology plays a core role of "connecting the preceding and the following" in industrial wastewater zero discharge (ZLD), and its application process is a systematic project of gradual concentration and classified treatment. It is located after pretreatment and before evaporation and crystallization, and its main task is to greatly reduce the volume of wastewater (reduction) and separate high-purity fresh water (resource utilization) at the same time, so as to "reduce the burden" for the subsequent high-energy-consuming evaporation and crystallization process.

Tertiary Membrane Concentration and Salt Separation

In a typical zero discharge project, membrane separation technology usually adopts a tertiary combined process of "ultrafiltration (UF) → reverse osmosis (RO) → high-pressure reverse osmosis/nanofiltration (HPRO/NF)".

First Stage: Ultrafiltration (UF) — Precision Security

Function: As the "vanguard" of reverse osmosis, it mainly removes residual suspended solids (SS), colloids, bacteria and macromolecular organics in wastewater after pretreatment.Principle: Utilizes physical sieving to retain substances with a particle size larger than 0.01 microns.Purpose: Protect the subsequent expensive reverse osmosis membranes from clogging (fouling) or scratching, and ensure that the pollution index (SDI) of the influent water of the reverse osmosis system meets the standard.

Second Stage: Reverse Osmosis (RO) — Main Force for Desalination

Function: This is the core desalination unit of the zero discharge system, responsible for separating about 70%-80% of the water from the wastewater to obtain high-quality reclaimed water.Principle: Driven by high pressure, water molecules pass through the semipermeable membrane, while dissolved salts and organics are retained to form concentrated water.Purpose: Realize the reduction of wastewater. RO produced water can usually be directly reused in production or cooling systems, while RO concentrated water enters the next stage of treatment.

Third Stage: Advanced Concentration and Salt Separation

According to water quality characteristics and resource utilization requirements, this stage usually has two technical paths:Path A: High-pressure reverse osmosis (HPRO/DTRO) — Extreme Concentration

· Applicable scenario: No special separation requirements for salt types, or mixed salt crystallization process is adopted in the follow-up.

· Function: Utilize pressure-resistant membrane components (such as disc tube reverse osmosis DTRO) to further concentrate RO concentrated water to a TDS (total dissolved solids) of 50,000-100,000 mg/L or even higher.

· Purpose: Minimize the volume of liquid entering the evaporation and crystallization system, thereby greatly reducing evaporation energy consumption.

Path B: Nanofiltration (NF) — Salt Separation and Crystallization

· Applicable scenario: Wastewater contains both sodium chloride (NaCl) and sodium sulfate (Na₂SO₄), and it is expected to recover high-purity industrial salt.

· Function: Utilize the selective retention characteristics of nanofiltration membranes for monovalent ions (Na⁺, Cl⁻) and divalent ions (Ca²⁺, Mg²⁺, SO₄²⁻) to separate wastewater into "monovalent salt concentrated water" and "divalent salt concentrated water".

· Purpose: Classified crystallization. Monovalent salt concentrated water is sent to evaporation and crystallization to produce sodium chloride, and divalent salt concentrated water is sent to crystallization to produce sodium sulfate, avoiding the production of difficult-to-dispose "mixed salt" and realizing real resource utilization.

The application of membrane separation technology in zero discharge is essentially "replacing energy with membranes". Through physical sieving and selective permeability, it limits the high-energy-consuming evaporation process to a very small volume of concentrated water, which not only reduces the overall operation cost, but also converts pollutants into valuable industrial salt through salt separation technology, perfectly conforming to the concept of "circular economy" and "green development".

With the rapid iteration of water treatment technologies, the water treatment industry has ushered in a golden development period, forming a full-chain technology system covering water intake - water use - drainage - reuse - resource utilization:

· Water-saving technologies: Improvement of circulating water concentration multiple, high-efficiency water-saving appliances, closed circulating systems, utilization of waste heat and pressure;

· Pretreatment technologies: Coagulation, sedimentation, filtration, air flotation, neutralization, oil removal, demulsification;

· Biological treatment technologies: Activated sludge process, A/O, A²/O, SBR, MBR membrane bioreactor, anaerobic ammonium oxidation;

· Advanced treatment technologies: Ultrafiltration (UF), reverse osmosis (RO), nanofiltration (NF), electrodeionization (EDI), advanced oxidation processes (AOPs), ozone catalytic oxidation;

· Resource utilization technologies: Reclaimed water reuse, brackish water desalination, heavy metal recovery, salt resource utilization, sludge incineration/composting/masonry;

· Intelligent management and control: Online monitoring, Internet of Things, digital twin, intelligent chemical feeding, leakage control, energy consumption optimization.

In the wave of global industrialization, many economies around the world have experienced the pains of "pollution first, treatment later", and in the process, spurred the leaping development of water treatment technologies. Their experience confirms the positive symbiotic law of industrialization and water treatment:

1. Japan: Full-scale Outbreak of Water Governance After Rapid Economic Growth

After World War II, Japan's industrialization boomed, and the direct discharge of industrial wastewater triggered public hazard incidents such as Minamata disease and Itai-itai disease, with frequent river pollution and urban water shortages. After the 1970s, the Water Pollution Control Act and the River Act were issued, mandating industrial wastewater treatment, water recycling and reclaimed water reuse, promoting the rapid breakthrough of membrane technologies, coagulants and industrial water-saving equipment. Japan's industrial water reuse rate has long been among the top in the world, completing the transformation from a "major polluting country" to a "water-saving power".

Japan has an "impeccable pipe network" system, with a large-scale underground drainage pipeline known as the "underground palace". Japan has extremely strict industrial drainage standards, even prohibiting kitchen oil pollution from entering drainage pipes. On the technical side, Japanese enterprises (such as Kurita Water Industries and Toray Industries) have profound technical accumulation in membrane materials and the treatment of high-difficulty industrial wastewater (such as electroplating wastewater and fluorine-containing wastewater).

Similarities with China: Both have experienced a shift from "focusing only on production" to "valuing environmental infrastructure", and face fierce competition in the manufacturing of high-end equipment such as membrane technologies.

2. Germany: Transformation of the Ruhr Industrial Zone from "Black Water" to "Clear Water"

The Ruhr Area rose on the basis of coal and steel, and the Emscher River was once one of the most polluted rivers in Europe. The direct discharge of industrial sewage and mine water led to ecological collapse. Through rainwater and sewage diversion, centralized sewage treatment, ecological restoration and transformation of industrial circulating water systems, coupled with the EU Industrial Emissions Directive (IED) and Best Available Techniques (BAT), Germany has taken the lead in high-salt wastewater treatment, sludge resource utilization and energy self-sufficiency technologies, and the heavy industrial area has seen a return of clear water and green banks.

Germany is a world leader in sludge management and phosphorus recovery technologies. German law mandates the recovery of phosphorus resources from sludge and prohibits land application of sludge, promoting the application of advanced technologies such as the PRISA process. At the same time, Germany has mature experience in the advanced treatment and resource utilization of industrial wastewater.

Similarities with China: Both have a huge heavy industry foundation (such as iron and steel and coal), face the problem of treating historical legacy pollution in industrial transformation, and emphasize the realization of waste resource utilization through technical means.

3. USA: Legislation-driven Standardization of Industrial Water Treatment

The enactment of the Clean Water Act and the establishment of the EPA in 1972 ended the era of unregulated industrial pollutant discharge, mandated the construction of industrial wastewater treatment facilities, and promoted the industrialization of technologies such as reverse osmosis, ion exchange, activated carbon adsorption and advanced oxidation. The reuse rate of industrial wastewater and the reduction rate of pollutants have been greatly improved, forming the world's most complete industrial water treatment standard, equipment and service system.

4. South Korea: Catching Up with Industrialization and River Basin Governance Simultaneously

The Han River and Cheonggyecheon Stream once turned into "stinking ditches" due to industrial expansion. Taking comprehensive river basin governance, upgrading of industrial wastewater treatment standards and construction of reclaimed water reuse pipe networks as the starting point, South Korea has strictly implemented pollutant discharge permits and total quantity control, quickly made up for the shortcomings of water treatment, and supported the upgrading of the manufacturing industry and the improvement of urban ecology.

South Korea has successful practices in river ecological restoration, water quality improvement and advanced treatment of urban sewage. Through large-scale projects such as the Cheonggyecheon Restoration Project, South Korea has demonstrated how to realize the harmonious coexistence of industrial drainage and ecological landscape in a high-density urban environment.

Similarities with China: Both have experienced the stage of black and odorous water systems during rapid urbanization, and both carry out governance through large-scale engineering measures (such as sewage interception and dredging) combined with biological and ecological technologies.

5. Singapore: Resource Constraints Spur the "Newater" Revolution

With a small territory and no natural water sources, Singapore has spurred technological breakthroughs due to extreme water shortage. Water-intensive industries such as petrochemicals and electronics are mandated to reuse all wastewater. The combined MBR and RO process is used to produce Newater, realizing the conversion of sewage into drinking water, near zero industrial discharge and self-sufficiency in water resources. Singapore's industrial sewage recovery and utilization rate is as high as over 85%, and the reclaimed water reuse rate also reaches over 60%. Its water treatment technology not only serves industry, but also purifies domestic sewage to drinking water standards through Newater technology, realizing closed-loop management of water resources.

Similarities with China: Both face the contradiction between industrial water demand and insufficient water resource endowment, and both realize the transformation of "obtaining resources from sewage" through cutting-edge technologies such as membrane technologies (reverse osmosis, ultrafiltration) and advanced oxidation.

Typical Cases

· Johor Palm Oil Wastewater Zero Discharge Project: Adopting the IC anaerobic reactor + ultrafiltration + reverse osmosis process, it treats 800 cubic meters of high-concentration wastewater per day, with a COD removal rate of over 99% and a reclaimed water reuse rate of 95%, and recovers crude oil to create economic benefits; the Johor Data Center Reclaimed Water Project supplies 4,000 cubic meters of cooling water per day, replacing tap water with reclaimed water to break the industrial water use bottleneck.

· TSMC Southern Science Park Reclaimed Water Plant: The world's first project to reuse industrial wastewater for wafer manufacturing, producing 20,000 tons of reclaimed water per day, with a target reclaimed water replacement rate of 60% by 2030; Chimei EDR Water Resource Center: the largest electrodeionization regeneration system in the petrochemical industry, producing 3,000 tons of reclaimed water per day for reuse in the manufacturing process.

· Ulsan Taehwa River Governance: Intercepting an 8.8-kilometer sludge belt, constructing a sewage treatment facility with a daily treatment capacity of 40,000 tons, implementing the joint governance of one enterprise and one river, the water quality has been upgraded from inferior Class V to Class I, becoming a model for water ecological restoration in industrial cities.

As the world's largest industrial country, China's industrialization process is highly synchronized with the growth of the water treatment industry:

· With the rapid expansion of industry, the proportion of industrial water consumption has continued to rise, and water resource shortage and river basin pollution have become development bottlenecks;

· After 2010, policies have been comprehensively tightened, with water conservation first, spatial balance, systematic governance, and simultaneous efforts of the government and the market becoming the water governance policy, and industrial water conservation, wastewater reuse and zero discharge being comprehensively promoted;

· At present, the reuse rate of industrial water, the up-to-standard discharge rate of wastewater and the utilization rate of reclaimed water are steadily increasing, the localization rate of membrane materials, water treatment chemicals, complete sets of equipment and smart water services has been significantly improved, and centralized sewage treatment in industrial parks, resource utilization of industrial wastewater and energy-saving water treatment under the dual carbon goals have become the main directions.

With a super-large market, a complete industrial chain and rapid technological iteration, China is taking a feasible path for developing countries of "industrialization - water resource constraints - water treatment upgrading - green high-quality development".

With the advancement of the Belt and Road Initiative, China's water treatment technologies are accelerating their global expansion. China has not only built the world's largest nanofiltration tap water plant, but also its total municipal sewage treatment scale with MBR (membrane bioreactor) has reached nearly 50 million tons per day, ranking first in the world. From palm oil wastewater treatment in Southeast Asia, to desert sewage treatment in Dubai in the Middle East, and then to port water treatment stations in Guinea in Africa, Chinese technologies have won extensive recognition in the international market for their wide adaptability, low cost and high efficiency. Domestic enterprises such as Hydranautics China, OriginWater and Bluestar Toray have occupied a dominant position in the market, with a total enterprise market share of up to 78%.

Chinese water treatment enterprises are no longer just equipment suppliers, but providers of "comprehensive solutions". In Belt and Road countries such as Côte d'Ivoire, Uzbekistan and Malaysia, Chinese enterprises combine China's advanced concepts such as smart water services, decentralized governance and zero discharge with local realities through the model of "central enterprise platform + private enterprise technology", not only exporting technologies, but also exporting standards and management experience.

China's position in global water treatment technologies has shifted from a "follower" to a "runner-up" and even a "leader". In the "leading" fields such as MBR municipal sewage treatment and complex water source treatment, China has an absolute advantage; in the "co-running" fields such as nanofiltration and MABR, China is rapidly catching up and realizing localization. China is contributing "Chinese wisdom" to global water security.

Industrial development and the water treatment industry are not opposed, but a dialectical unity of constraints and breakthroughs, crises and opportunities, and costs and upgrades. The industrialization process of developing countries has repeatedly proved that the red line of water resources is a catalyst for industrial transformation, and water treatment technology is a safety valve for industrial civilization. The shift from extensive water intake to water recycling, reclaimed water reuse, near zero discharge, energy conservation and emission reduction is a revolution in the way of water resource utilization. Water is the blood of industry, and industry is the backbone of national modernization. The history of a country's industrial rise is essentially also an evolutionary history of the development, utilization, constraint and regeneration of water resources. In the stage of rapid industrialization, developing countries generally experience a typical path of "large-scale industrial expansion - surging industrial water use - water resource shortage - rigid policy regulation - outbreak of water treatment technologies - popularization of water recycling". The "water dilemma" of industrial development is ultimately transformed into a "new opportunity" for the water treatment industry. The water treatment industry will continue to support the steady and long-term development of national industrial high-quality development and ecological civilization construction with technological innovation, industrial upgrading and ecological empowerment.