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.
A year-long full-scale trial at a Sierra-foothills municipal wastewater plant in Northern California removed 94% of dissolved copper and roughly 70% of dissolved zinc. JC 9830 metal precipitant at 10 mg/L and JC 1687 cationic coagulant at 10 mg/L held effluent copper below 1.4 ppb against a 3.1 ppb discharge limit.
Last updated 5 August 2026
The Problem
What was the copper problem?
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
How did Jenfitch remove the copper?
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
What were 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.
The Numbers
Sample-by-sample results
The headline figure from the trial is 94% dissolved copper removal, but the value of a full-scale, year-long program is that it is sampled repeatedly against a moving influent. Copper into the plant ranged from 28 to 58 ppb across the sampling dates below, and effluent stayed under the 3.1 ppb discharge limit throughout.
| Date | Influent Cu | Effluent Cu | Cu removal | Zn removal |
|---|---|---|---|---|
| March 11 | 35 ppb | 2.0 ppb | 94.3% | 68.9% |
| March 15 | 28 ppb | 1.6 ppb | 94.3% | 79.8% |
| March 30 | 58 ppb | 1.4 ppb | 97.6% | 76.0% |
| August 16 | 46 ppb | 3.8 ppb | 91.7% | 56.3% |
The March 30 row is the useful one for a permit discussion. Influent that day was the highest of the four at 58 ppb — roughly nineteen times the discharge limit — and effluent was the lowest at 1.4 ppb. Removal efficiency rose with loading rather than falling, which is the behaviour a plant needs when influent is not under its control.
The Chemistry
Why does sulfide precipitation beat hydroxide?
Most metals-removal programs precipitate metal hydroxides by raising pH. It works, but it carries three structural problems that show up as soon as a permit limit gets tight.
First, metal hydroxide is amphoteric — soluble at low pH and soluble again at high pH. There is a narrow window where it precipitates properly, and for copper the optimum sits near pH 8.1. Drift either side of that window and dissolved metal goes back into solution. Second, hydroxide precipitation produces a large volume of gelatinous sludge that dewaters badly, so the plant trades a water problem for a solids-handling problem. Third, where natural chelating agents are present in the wastewater — common in any collection system taking industrial or commercial flow — they bind the metal and block hydroxide precipitation outright.
Metal-sulfide precipitation with JC 9830 avoids all three. Copper sulfide precipitates across a broad pH range rather than in a narrow window, so it does not need tight pH control. It forms a dense, easily dewatered sludge, cutting handling volume. And it has a lower solubility than the corresponding hydroxide, which is the reason it can reach single-digit-ppb effluent at all — including where chelating agents would otherwise defeat a hydroxide program. As a secondary benefit, the same sulfide chemistry reduces hexavalent chromium to the trivalent form.
Pairing JC 9830 with the cationic coagulant JC 1687 at the secondary-clarifier inlet is what turns the precipitate into a floc that actually settles. The precipitant makes the particle; the coagulant makes it heavy enough to leave the water.
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. Influent copper at the Sierra-foothills plant ranged from 28 to more than 70 ppb, and the discharge limit itself was confirmed by a Water-Effect Ratio study. Removal came from the JC 9830 and JC 1687 program, which took out 94% of dissolved copper.
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. Metal sulfides precipitate across a broad pH range, form a dense sludge that is easier to dewater, and have lower solubility than the corresponding hydroxides. Sulfide precipitation also works where natural chelating agents would otherwise block hydroxide precipitation and leave metals dissolved in the effluent.
