94% Dissolved Copper Removal at a Northern California Municipal Plant
A full-scale, year-long trial at a Sierra-foothills municipal wastewater plant pulled dissolved copper below its discharge limit using the JC 9830 + JC 1687 program.
The Problem
The Challenge
A municipal wastewater treatment plant in the Sierra foothills of Northern California faced dissolved copper in its influent ranging from 28 to more than 70 ppb. That left effluent exceeding the plant's 3.1 ppb dissolved-copper discharge limit — a limit confirmed by a Water-Effect Ratio study.
Conventional hydroxide precipitation was a poor fit. Metal hydroxide is amphoteric — soluble at both low and high pH, with an optimum copper pH near 8.1 — and it generates excessive, hard-to-dewater sludge. Worse, natural chelating agents in the water can block hydroxide precipitation entirely, leaving copper dissolved and in the effluent.
Why sulfides beat hydroxides
Copper sulfide precipitates over a broad pH range, forms a dense, easy-to-dewater sludge, and has lower solubility than copper hydroxide — so it delivers higher removal, and it works even where chelating agents defeat hydroxide precipitation. The same chemistry also converts hexavalent chromium to trivalent chromium.
The Program
The Jenfitch Solution
Jenfitch deployed a two-product program built around metal-sulfide precipitation followed by coagulation:
- JC 9830 metal precipitant @ 10 mg/L dosed into the aeration-basin discharge, forming an insoluble copper-sulfide precipitate.
- JC 1687 cationic coagulant @ 10 mg/L dosed at the secondary-clarifier inlet, building a dense, fast-settling floc to capture the precipitate.
- Full-scale operation over a one-year trial on the live plant — not a bench simulation.
- Removal that holds across a broad pH range, unaffected by the chelating agents that block hydroxide precipitation.
The Data
The Results
| Sample date | Influent Cu (ppb) | Effluent Cu (ppb) | Cu removal | Zn removal |
|---|---|---|---|---|
| March 11 | 35 | 2.0 | 94.3% | 68.9% |
| March 15 | 28 | 1.6 | 94.3% | 79.8% |
| March 30 | 58 | 1.4 | 97.6% | 76.0% |
| August 16 | 46 | 3.8 | 91.7% | 56.3% |
Below the limit, for a full year
Across the trial the program removed 94% of dissolved copper and roughly 70% of dissolved zinc, holding effluent copper below 1.4 ppb — well under the 3.1 ppb discharge limit, with non-detect / <0.5 ppb results in other trials.
Documentation
Read the full study
Related: Metal Removal program · Municipal & Industrial research
Frequently Asked Questions
About this copper-removal program.
What products were used and at what dose?
JC 9830 metal precipitant was fed at 10 mg/L into the aeration-basin discharge, and JC 1687 cationic coagulant was fed at 10 mg/L at the secondary-clarifier inlet. JC 9830 forms an insoluble copper sulfide; JC 1687 builds a dense floc that settles the precipitate.
Why not use conventional hydroxide precipitation?
Metal hydroxide is amphoteric (soluble at low and high pH), makes excessive hard-to-dewater sludge, and can be blocked entirely by natural chelating agents. Copper sulfide precipitates over a broad pH range with lower solubility and a denser sludge, so it removes more copper more reliably.
Did the program meet the discharge limit?
Yes. Across the year-long full-scale trial it held effluent copper below 1.4 ppb — under the plant's 3.1 ppb dissolved-copper discharge limit — while removing about 70% of dissolved zinc.
Does it help with other metals?
Yes. In addition to copper and zinc, the sulfide chemistry converts hexavalent chromium to trivalent chromium and removes other dissolved metals as insoluble sulfides.
