Electrocatalytic Oxidation for High-Salinity Organic Wastewater: How Far Current Standards Reach

1. First, the Honest Position: No Dedicated Engineering Code

Unlike Fenton oxidation, which has HJ 1095-2020, or catalytic ozonation, which has group standards, electrocatalytic oxidation occupies a thinner position in the standards system, and that needs saying plainly. The position can be summarised in three points: first, the ecological and environmental standards system contains no engineering specification for electrocatalytic oxidation; second, at national level there is only a plan in development; third, the only dedicated document in force is a group standard. Writing these three points into a scheme is far more defensible than vaguely citing common industry practice.

2. The Only Clause in a Current National Environmental Standard

Clause 6.3.5 of HJ 2057-2018, Technical Specifications for Lead Smelting Wastewater Treatment, sets out process conditions for electrochemical oxidation and is one of the few written provisions on electrochemical oxidation in current national environmental standards. Clause 6.3.5.2 requires the following:

1. Influent pH after pretreatment preferably between 5 and 9.
2. An aeration device preferably provided in the electrochemical system.
3. Solid-liquid separation must provide oxidation, flocculation and sedimentation functions.
4. Coagulant dose preferably determined by testing.
5. Depending on influent quality and the discharge limit, two-stage electrochemical oxidation in series may be used, with solid-liquid separation provided after each stage.
6. Lime neutralisation may be used as pretreatment.

Clause 6.2.5 adds the principle that electrochemical treatment generally requires pretreatment and can be combined with lime neutralisation, and clause 8.2.6 requires the electrochemical unit to be equipped with current and voltage monitoring.

Two caveats apply. First, this standard addresses lead smelting wastewater, where electrochemical oxidation targets heavy metals and co-existing pollutants rather than mineralisation of high-salinity organic streams, so its process conditions cannot be transplanted as design parameters for electrocatalytic oxidation. Second, the items it does give, pH 5 to 9, aeration, two-stage arrangement and separation after each stage, are configuration-level requirements that remain useful for any electrochemical oxidation unit.

3. The National Plan: 20255599-T-606 Is Being Drafted

The national standard information platform shows that national standard plan 20255599-T-606, Electrochemical Technology Specifications for Industrial Wastewater Treatment, Part 2: Electrochemical Oxidation, is administered by the National Technical Committee on Chemistry for Standardization and executed by its water treatment chemicals subcommittee, with the China Petroleum and Chemical Industry Federation as the competent authority. The plan was issued on 31 October 2025 with an 18-month cycle and is currently in the drafting stage.

Its scope statement is worth quoting closely: the series is divided into three parts, general principles, electrochemical oxidation and electrocoagulation; this part specifies electrochemical equipment, process selection and operating parameters, installation and commissioning, acceptance, operation and maintenance for electrochemical oxidation applied to industrial wastewater, and applies to engineering design, construction, acceptance, operation and maintenance. Main technical contents are electrode types and applicability, reactor structure types and applicability, assembly of electrochemical equipment, treatment process and operating parameters, installation and commissioning, acceptance, and operation and maintenance.

In other words, electrode selection, reactor structure and operating parameters are all still being written; there are no formal provisions to cite yet. At scheme stage this document can only be referenced as evidence of standardisation progress, not as a source of values.

4. The Group Standard: T/CITS 416-2025 Defines the Scope

T/CITS 416-2025, Technical Requirements for the Treatment of High-Salt Organic Wastewater Based on Electrocatalytic Oxidation Method, was issued and made effective by the Chinese Society of Inspection and Quarantine on 23 May 2025. Its scope covers abbreviations, basic requirements, process requirements, environmental requirements, electrical and automation equipment requirements and safety requirements, and applies to the treatment of high-salt organic wastewater by electrocatalytic oxidation, targeting removal of ammonia nitrogen, organic nitrogen, complexed heavy metals and chlorate in high-salt organic wastewater with chemical oxygen demand between 30 and 100 000 mg/L.

Its value lies in two points. First, it defines the applicable COD range as 30 to 100 000 mg/L, spanning nearly four orders of magnitude, which implies design by water quality band rather than a single operating case. Second, it extends the target pollutants beyond COD to ammonia nitrogen, organic nitrogen, complexed heavy metals and chlorate, which matches the actual pollutant spectrum of high-salinity streams better. It also contains dedicated chapters on electrical and automation equipment and on safety, constraining by-product risk in chloride-bearing systems and electrical safety.

5. Core Parameters Come Only From Testing: The Checklist

From the three documents above it follows that current density, electrode gap, residence time, the electrode area basis, conductivity and electrolyte dosing have no citable standard values. Following the technical framework set out in the national plan, bid evaluation and acceptance should require the supplier to commit in writing to at least the following:

• Electrode type and applicability: anode material, substrate and coating system, plus expected service life and replacement interval for this water.
• Reactor structure and applicability: flow channel form, single versus multi-stage layout, and the conversion between effective electrode area and geometric area.
• Operating parameters: current density, stating whether based on geometric or electrochemically active area, cell voltage, electrode gap, hydraulic residence time, and the influent pH and conductivity window.
• Performance and energy: COD removal, mineralisation, current efficiency, specific energy per cubic metre and per kilogram of COD, with the test water quality and test duration stated.
• By-products and safety: formation of active chlorine and chlorate in chloride-bearing systems, off-gas composition, and electrical safety and protective measures.
• Installation, commissioning and acceptance: build the acceptance programme against the three chapters on installation and commissioning, acceptance, and operation and maintenance in the national plan.

One specific caution: current density must always state its area basis. Geometric and electrochemically active area differ by a factor of several times, and quotations that omit this cannot be compared side by side.

6. What Can and Cannot Be Fixed

• Can be fixed: pretreatment before the unit, pH control at 5 to 9 per clause 6.3.5.2 of HJ 2057-2018, aeration provided in the system, solid-liquid separation after each stage, current and voltage monitoring per clause 8.2.6, and the applicable COD band of 30 to 100 000 mg/L per T/CITS 416-2025.
• Cannot be fixed, must come from testing: current density, cell voltage, electrode gap, residence time, electrode life, specific energy consumption and by-product formation. No standard values exist, so any quoted figure should be accompanied by a test report and its test conditions.
• To keep tracking: progress on national standard plan 20255599-T-606, which on publication will provide the first unified basis for electrode selection and operating parameters.

In one sentence: electrocatalytic oxidation of high-salinity organic wastewater is entirely workable in engineering terms, but at present it is a process with a group standard and without a national code. Configure the train against clause 6.3.5 of HJ 2057-2018, bound the applicability with T/CITS 416-2025, and put the operating parameters into a contract annex backed by test data. That is the safest route today.