Hank Zhou · OTIA

Where Does the Color Go?

Tracing Water Through a Textile Dyeing Factory

Water had been part of my life for years, from the Qiantang River to mountain streams in Yubeng. At a textile dyeing factory in Taizhou, I started asking a different question: what happens to water after dyeing?

Start the story Story → factory research → evidence → policy
Snow-covered mountains in Yubeng, Yunnan, beneath a blue sky and clouds in June 2025.
Snow-covered mountains in Yubeng, Yunnan, June 2025. Photograph by Hank Zhou.
01 · My Story

Water, Before It Became Research

I did not set out to connect these places. Water was simply something I kept noticing.

Mountain water flowing through a rocky stream in Yubeng, Yunnan, June 2025.
Yubeng, Yunnan · June 2025
Yubeng, Yunnan

Mountain water

I hiked through Yubeng in June 2025. I remember the cold, clear water mostly as part of the landscape; I was not thinking about factories or environmental policy.

Participants walking onto a riverside observation platform during Qiantang River field research in Zhejiang, 2024–2025.
Qiantang River field research · Zhejiang · 2024–2025
Qiantang River, Zhejiang

Looking more closely

Closer to home, I joined Qiantang River field research. It taught me to slow down, observe a water system, and record what I actually saw.

These experiences were not preparation for the factory project. They were simply part of why water was already familiar to me when a new question appeared.

02 · Research

Following Water Through the Factory

In Taizhou, water stopped being just something I observed. I began tracing what happened to it step by step.

Outdoor wastewater-treatment tanks with factory buildings in the background at the factory I studied in Taizhou.
Wastewater-treatment area at the textile dyeing factory I studied in Taizhou.
Taizhou, Zhejiang

The question became concrete

I followed water from dyeing and rinsing into the treatment system, then compared what I saw with staff interviews, design documents, and monitoring records.

Where does the color go after it leaves the fabric?

This website studies one factory. I use the city-level location for privacy and do not treat the factory as representative of the whole industry.

Research geography · real relative locations · not a water-flow route
Map of China showing the real relative locations of Yubeng, Hangzhou, Haining on the Qiantang River, and Taizhou.
03 · Inside the Wastewater System

What Happens After Dyeing?

I asked staff to walk me through what happens after dyeing and compared their explanations with the factory design document. The eight steps below are my simplified version of that process.

Wastewater main line Sludge line Reuse / approved discharge branch
01

Wastewater Collection & Balancing

Collected wastewater is balanced to stabilize flow and concentration before treatment.

02

Cooling / Heat Exchange

Wastewater is cooled before entering the biological treatment stages.

03

Anaerobic Treatment

Anaerobic conditions help break down complex organic matter before aerobic treatment.

04

Aerobic Treatment

Aeration supports microorganisms that further break down organic pollutants.

05

Secondary Clarification

Solids settle out, separating sludge from treated water after biological treatment.

06

Chemical Dosing & Air Flotation

Chemicals and air flotation remove additional suspended material after clarification.

07

Final Monitoring

Final outlet conditions are checked at the monitored discharge point, DW001.

08

Reuse / Approved Discharge

Treated water may be reused or leave through an approved discharge route.

Sludge branch
Secondary-clarifier sludge + air-flotation sludge → sludge tank → plate-and-frame filter press → approved off-site disposal.
Filtrate return
Filter-press liquid returns to the front of the wastewater treatment system rather than being treated as a final discharge.
Design value: the factory diagram labels influent as 2,000 t/day. This website treats that number as a documented design flow, not as proof of actual daily treatment volume.
Sludge branch: secondary-clarifier and air-flotation sludge → sludge tank → plate-and-frame filter press → approved off-site disposal. Filter-press liquid returns to the front of the treatment system.
My simplified wastewater-treatment diagram. I built this from the factory design document and staff interviews. I separated the main wastewater line, sludge handling, and the final reuse / approved-discharge branch, and I did not add a downstream route that I could not verify.

From the Diagram to the Site

Once I understood the diagram, I matched several steps to photographs from the actual treatment area.

Wastewater regulating tank at the factory I studied.
Wastewater regulating tank. Incoming wastewater is collected and balanced before later treatment stages. Verified factory photograph from the project materials.
Aerobic treatment tank with aeration infrastructure at the factory I studied.
Aerobic treatment. A biological-treatment tank at the factory I studied, photographed during the project.
Air-flotation treatment tank at the factory I studied.
Air-flotation stage. Photograph identified in the project materials with the air-flotation part of the treatment system.
Plate-and-frame filter press used for sludge dewatering at the factory I studied.
Sludge dewatering equipment. Plate-and-frame filter-press equipment documented at the factory I studied.
04 · Evidence & Interviews

What Did I Find?

I used one monitoring report and three staff interviews. The numbers showed me what was measured; the interviews showed me how the system worked day to day.

Monitoring evidence

25 June 2026 outlet snapshot

A third-party report recorded three measurements at the final outlet, DW001. I use it as a one-day snapshot, not as proof of long-term performance.

7.6 · 7.7 · 7.6pH · three reported measurements
8 · 9 · 8 mg/LSuspended solids · three reported results
20 · 20 · 20Color · dilution-times, three reported results
Sampling date25 June 2026
Sampling pointDW001 · final outlet
Report identifierZJYX2606094

Limit: one sampling date cannot show a long-term trend or a before-and-after treatment effect.

Interview evidence

Three people, three parts of the system

I asked people in different roles what environmental management looked like from where they stood.

Environmental manager
The factory is the main party responsible for environmental protection. The third-party agency conducts testing, while government departments provide guidance and supervision.
Translated from Chinese interview · 2026
Wastewater treatment technician
We should reduce pollution at the source: use water as efficiently as possible, use more reclaimed water, and reduce the amount of wastewater.
Translated from Chinese interview · 2026
Laboratory & production employee
We have production reports every day. The next day we total water, electricity, and steam against output. If something looks abnormal, we report it and trace the cause.
Translated from Chinese interview · 2026

Interview note: these statements are firsthand accounts, not independently verified facts.

DESIGN DOCUMENTprocess-stage values / targetsOBSERVED OUTLET25 June 2026 third-party samples
Bar chart titled Suspended solids across the treatment process, comparing design-document values with three third-party outlet samples collected on June 25, 2026.
Suspended solids. Design-document values are shown separately from the three observed outlet samples on 25 June 2026.
DESIGN DOCUMENTprocess-stage values / targetsOBSERVED OUTLET25 June 2026 third-party samples
Bar chart titled Color across the treatment process, comparing design-document ranges with the third-party outlet result collected on June 25, 2026.
Color. Design-document ranges are shown separately from the observed outlet result on 25 June 2026.
05 · Policy Brief

From Compliance to Water Reuse

The interviews left me with one question: could policy encourage factories to use less freshwater, not just meet a discharge standard? I proposed a small, one-year pilot to test that idea.

01

Technical review

A short water audit and practical advice so each factory can choose one or two realistic changes.

02

Partial start-up grants

Shared support for meters, pipes, tanks, controls, or small process changes.

03

Performance rewards

Payment only after independent verification of water savings or reduced wastewater per unit of production.

04

Simple annual reporting

One standard form for water, production, reuse, discharge, and compliance data.

How the pilot would work

Baseline
Technical Review
Installation
One-Year Pilot
Independent Verification
Decision on Expansion

Measures of success

  • Freshwater use per unit of production
  • Wastewater volume per unit of production
  • Share of water safely reused within the factory
  • Continued discharge compliance
  • Public cost per cubic metre of water saved
  • Participation rate and continuation after funding ends

Risks and safeguards

Risk · paying for changes already plannedRequire a verified baseline, an approved project plan, and evidence that funded changes are additional.
Risk · lower production looks like water savingsMeasure water per unit of production and record major changes in product mix.
Risk · large firms capture most supportReserve part of the budget for smaller firms and provide shared technical assistance.
Risk · reused water affects product qualityStart with technical review and allow limited applications before expansion.
Risk · volunteers look like the whole sectorPublish participation criteria and treat the pilot as a test, not proof of sector-wide impact.
Risk · compliance gets treated as optionalParticipation must never replace permit, monitoring, or enforcement requirements.
06 · Methods, Sources & Reflection

What I Learned and What I Still Cannot Know

I started this project thinking the main question was basically, “Does the treated water meet the standard?” By the end, that felt too narrow. I became more interested in what could change before the final outlet: less freshwater in, more reuse where it makes sense, and less wastewater to treat.

What changed for me

The biggest change in my thinking was separating compliance from prevention. A factory can meet its final discharge requirements and still have reasons to use less freshwater or create less wastewater in the first place.

I also learned how quickly a good environmental idea turns into a measurement problem. If production falls, water use can fall too. If a factory already planned an upgrade, a subsidy should not claim credit for it. Those details made my policy proposal much more cautious.

Finally, my family connection gave me access to details I would not otherwise have seen, but it is also a limitation. I can describe this factory closely; I cannot pretend it represents every dyeing factory in Taizhou.

How I did the research

I combined what I saw on site with three staff interviews, 36 wastewater records, factory design materials, and one third-party monitoring report from June 2026.

Factory visit / site observation
Semi-structured interviews
Reviewed and analyzed 36 wastewater records
Wastewater-treatment design documents
Third-party monitoring report
Policy analysis
Simplified public communication & data visualization

Disclosure

The factory in this project is my grandfather's textile dyeing factory. That relationship gave me access to staff and documents that I might not otherwise have seen. It may also have shaped what information was available to me and how I interpreted it.

Because of that, I label interview evidence clearly, separate design values from measured values, and do not treat this one factory as representative of the whole industry.

Sources

Interviews

Interview with the environmental manager, 2026.
Interview with the wastewater treatment technician, 2026.
Interview with the laboratory and production employee, 2026.

Factory documents

Internal factory wastewater treatment design document (undated engineering document).
Factory pollutant-discharge permit requirements, as described in the environmental-manager interview.

Third-party monitoring

Third-party wastewater monitoring report, 25 June 2026, sampling point DW001, report identifier ZJYX2606094. The report is presented as a one-day outlet snapshot; the regulatory context on that date included the factory’s permit requirements and GB 4287-2012.

Policy and background sources

Ministry of Ecology and Environment of China. Discharge Standards of Water Pollutants for Dyeing and Finishing of Textile Industry, GB 4287-2012. This standard was in force on 25 June 2026, the date of the monitoring report.
Ministry of Ecology and Environment of China. Discharge Standard of Water Pollutants for Textile Industry, GB 4287-2026. The transition notice applies the new standard to new enterprises from 1 September 2026 and to existing enterprises from 1 January 2028.
Ministry of Ecology and Environment of China. Announcement No. 29 of 2026, which specifies the implementation dates for new and existing enterprises.
International Finance Corporation, World Bank Group. Environmental, Health, and Safety Guidelines for Textile Manufacturing (2007), used as general background on industrial water use, wastewater management, and pollution prevention.