Medical Facility Wastewater Treatment and Disinfection: Reconciling the 2026 Amendment to GB 18466-2005 with HJ 2029-2013

1. Division of labour between two documents, and the scale of the 2026 amendment

Medical facility wastewater treatment rests on two primary documents with distinct roles: GB 18466-2005, Discharge standard of water pollutants for medical organization, a mandatory national pollutant discharge standard governing "what the discharge must look like"; and HJ 2029-2013, Technical specifications for hospital sewage treatment (approved by the Ministry of Environmental Protection on 2013-03-29, effective 2013-07-01, first issuance, a guidance document) governing "how the plant is built and operated".

In 2026 this must be rewritten. On 2026-05-28 the Ministry of Ecology and Environment and the State Administration for Market Regulation approved, and on 2026-06-02 issued, the Amendment to GB 18466-2005. The announcement states that the amendment has mandatory force: new, expanded and reconstructed medical facilities, and "dual-use" public infrastructure with isolation or emergency medical functions during major epidemic control periods, shall apply it from 2026-09-01; existing medical facilities from 2028-09-01. The two-year gap means new-build and retrofit projects and legacy operation and maintenance projects sit on entirely different timelines and must not be conflated.

2. Discharge side: what the amendment changed

20 beds becomes a hard threshold

Amended clause 4.1.2: general medical organizations and other medical organizations with 20 beds or more shall meet Table 2; wastewater discharged to surface water bodies and sea areas shall meet the discharge standard, while wastewater discharged to sewers whose terminal has a normally operating municipal secondary treatment plant shall meet the pretreatment standard. Clause 4.1.3: general medical organizations with fewer than 20 beds and all other medical organizations shall disinfect their wastewater and meet the fecal coliform limit in Table 2 before discharge; where chlorine disinfectants are used, the total residual chlorine limit and process control requirements in Table 2 also apply; connection to the municipal sewer network or on-site further treatment is recommended afterwards.

Total residual chlorine plus contact time: now a compound requirement

Table 2 item 24 (general and other medical organizations): total residual chlorine - 0.5 mg/L at the main outlet (discharge standard); 3 to 10 mg/L at the contact tank outlet (discharge standard) or 2 to 8 mg/L (pretreatment standard), with contact time in the disinfection contact tank not less than 1.0 h. The table note states this applies only to chlorine disinfection processes and not to other disinfection methods.

Table 1 item 25 (infectious disease and tuberculosis facilities): 0.5 mg/L at the main outlet; 6.5 to 10 mg/L at the contact tank outlet, with contact time not less than 1.5 h.

Writing contact time into the limit table is one of the most substantive changes: measuring residual chlorine concentration without verifying contact time no longer constitutes compliance.

A new whole effluent toxicity item

Table 1 item 26 and Table 2 item 25 add zebrafish egg acute toxicity (dilution ratio): 6 for the discharge standard (where discharged to water bodies), with no requirement under the pretreatment standard. Clause 3.8 of the amendment defines the lowest ineffective dilution (LID) as the lowest dilution of a sample at which not less than 90% of zebrafish eggs survive after 48 h of incubation at 26 degrees C plus or minus 1 degree C. The supporting method standard is HJ 1069, Water quality - Determination of acute toxicity - Zebrafish egg method.

This is the first time a biological effect control requirement has been placed on medical facility wastewater alongside conventional physico-chemical and microbial items, mainly targeting emerging pollutants such as antibiotics. Clause 6.2.2.5 sets the monitoring frequency: for pollutant permit entities under key management, self-monitoring of whole effluent toxicity shall be at least once every six months; under simplified management, at least once a year; frequency shall be increased appropriately during major epidemic control periods.

Separate flow and pre-disinfection for infectious disease areas becomes mandatory

Clause 4.1.5: wastewater from infectious disease and tuberculosis facilities, and from the infectious disease areas (infectious disease outpatient clinics and wards) of general and other medical organizations, shall be separately collected and pre-disinfected before entering the treatment system, meeting the fecal coliform limit in Table 1 and, where chlorine is used, the total residual chlorine limit and process control requirements in Table 1. General and other medical organizations that do not separate and pre-disinfect such flows shall comply with Table 1 for their entire discharge. The last sentence is the enforcement lever: no separation means the whole facility is assessed as an infectious disease hospital.

"Dual-use" facilities brought into scope

Clause 4.1.6: during major epidemic control periods, dual-use public infrastructure with isolation or emergency medical functions shall disinfect its wastewater to the fecal coliform limit in Table 1 and, where chlorine is used, meet the Table 1 residual chlorine limit and process control requirements; it shall also control items 5 to 24 of Table 1, with limits set by GB 8978. Clause 4.2.2: such facilities, like infectious disease and tuberculosis facilities, shall disinfect the waste gas discharged from the treatment station.

Sludge: no longer characterized as hazardous waste, but must be disinfected

Clause 4.3 is amended to: sludge shall be disinfected and shall meet the requirements of Table 4 before it may be transferred, treated or disposed of, with former clauses 4.3.1 and 4.3.2 deleted. This is the change with the most direct engineering impact; see section 4 for the comparison with HJ 2029-2013.

3. Engineering side: core parameters of HJ 2029-2013 that remain valid

Design flow and quality

Clause 4.2.2 gives empirical design flow data by bed count: for well-equipped large hospitals with N not below 500 beds, q = 400 to 600 L/(bed.d) with a daily variation coefficient Kd of 2.0 to 2.2; for medium hospitals with 100 < N not above 499 beds, q = 300 to 400 L/(bed.d) with Kd 2.2 to 2.5; for small hospitals with N below 100 beds, q = 250 to 300 L/(bed.d) with Kd 2.5. Clause 4.2.4: the design margin should be 10% to 20% above measured or calculated values. Table 1 reference quality data: COD 150 to 300 (average 250), BOD5 80 to 150 (average 100), SS 40 to 120 (average 80), ammonia nitrogen 10 to 50 (average 30) mg/L, and fecal coliform 1.0x10^6 to 3.0x10^8 (average 1.6x10^8) per L.

Process route

Clause 6.1.2: wastewater from infectious disease hospitals shall, after pre-disinfection, use secondary treatment plus disinfection, or secondary plus advanced treatment plus disinfection. Clause 6.1.3: for non-infectious disease hospitals, where effluent is discharged directly or indirectly to surface water bodies or sea areas, secondary treatment plus disinfection or secondary plus advanced treatment plus disinfection shall be used; where effluent enters a municipal sewer network whose terminal has a normally operating secondary treatment plant, enhanced primary treatment plus disinfection may be used.

Clause 6.3.2.1 (activated sludge aeration tank): sludge load should be 0.1 to 0.4 kg-BOD5/(kg-VSS.d) and mixed liquor suspended solids should be maintained at 2 to 4 g/L. Clause 5.1.4: treatment structures shall be designed as two parallel trains. Clause 5.1.6: structures shall be corrosion-resistant, leak-proof and frost-protected, and should be covered and sealed with ventilation devices.

Disinfection: quantitative parameters for three methods

Chlorine disinfection (clause 6.3.4.1): the contact tank volume shall satisfy both contact time and sludge deposition; contact disinfection time should not be less than 1.5 h for infectious disease hospitals and not less than 1.0 h for non-infectious disease hospitals; the tank is generally divided into two cells of equal volume with guide walls to avoid short-circuiting, the length to width ratio should not be less than 20:1, and a sampling port shall be provided at the outlet; reference chlorine dose (as available chlorine) is generally 30 to 50 mg/L for enhanced primary treatment effluent and 15 to 25 mg/L for secondary and advanced treatment effluent, with the operating dose determined from residual chlorine and actual water quality and quantity; dosing equipment shall be provided in at least two sets, one duty and one standby. The clause also states that liquid chlorine is suitable where effluent enters a municipal sewer network, and that where effluent is discharged to surface water bodies, dechlorination shall be provided or chlorine use shall be cautious; liquid chlorine is not recommended for hospitals in densely populated areas or for small facilities.

Ozone disinfection (clause 6.3.4.2): dose 30 to 50 mg/L with contact time not less than 30 min for enhanced primary effluent; dose 10 to 20 mg/L with contact time 5 to 15 min for secondary effluent; coliform removal shall not be less than 99.99%; ozone in the treated tail gas shall be below 0.1 mg/L. The clause states that ozone should be preferred for infectious disease hospital wastewater and should be the first choice where effluent is reused or discharged to surface water bodies.

UV disinfection (clause 6.3.4.3): applicable where secondary effluent has 254 nm UV transmittance not below 60% and suspended solids below 20 mg/L; with suspended solids below 20 mg/L the recommended dose is 60 mJ/cm2 and irradiation contact time should exceed 10 s or be determined by testing; a closed UV system with automatic cleaning is recommended.

4. Conflicts: UV and sludge, where the amendment overrides HJ 2029-2013

These two points must be handled on the principle that the newer mandatory standard prevails; old wording must not be carried into design documents.

UV disinfection: suspended solids threshold tightened, dose reworded

Clause 6.3.4.3 of HJ 2029-2013 gives "a recommended dose of 60 mJ/cm2 where suspended solids are below 20 mg/L". Clause 5.7.1 of the amendment changes this to: for UV disinfection, suspended solids shall be below 10 mg/L, the irradiation dose should not be less than 40 mJ/cm2, and irradiation contact time should exceed 10 s or be determined by testing. The suspended solids threshold tightens from 20 to 10 mg/L, while the dose changes from "recommended 60" to "not less than 40". The first is a substantive tightening that raises the quality demanded of secondary effluent; the second changes a recommendation into a floor, and the two are not equivalent, so it cannot be read simply as a relaxation of dose.

Sludge: from "manage as hazardous waste" to "disinfect and meet Table 4"

Clause 6.3.5.3 of HJ 2029-2013 states that hospital sludge shall be managed as hazardous waste and centrally disposed of by a qualified hazardous waste operator. Clause 4.3 of the amendment replaces this with "sludge shall be disinfected and shall meet the requirements of Table 4 before transfer, treatment or disposal", deleting former clauses 4.3.1 and 4.3.2. The ministry's press briefing explains that the amendment no longer characterizes wastewater treatment sludge as hazardous waste, but makes clear that sludge must be disinfected and meet the relevant requirements before transfer and treatment.

This is not a relaxation. The sludge disinfection parameters of HJ 2029-2013 remain valid and are more specific: clause 6.3.5.1 requires the sludge holding tank to have an effective volume not less than 24 h of sludge production and preferably not less than 1 m3, with mixing provided; with lime disinfection, the lime dose is about 15 g/L of sludge, bringing pH to 11 to 12, with mixing contact for 30 to 60 min and storage for more than 7 days; with bleaching powder, the dose is about 10% to 15% of the sludge mass. Clause 6.3.5.2: centrifugal dewatering is preferred, dewatered sludge moisture content shall be below 80%, the dewatering process must include sealing and gas handling, and dewatered sludge shall be sealed for packaging and transport.

Disinfection performance is judged against Table 4 as referenced by clause 4.3 of the amendment; refer to the official standard text for the specific limits.

5. Other clauses refined by the amendment

• Septic tanks (clause 5.3): designed for maximum daily flow; retention 24 to 36 h and cleaning interval 180 to 360 d for infectious disease and tuberculosis facilities; retention 12 to 24 h and cleaning interval 90 to 180 d for general and other medical organizations.
• Radioactive wastewater (clause 5.4.1): treatment and discharge shall meet the discharge control requirements for radioactive substances in GB 18871 and the liquid radioactive waste management requirements in HJ 1188.
• Laboratory wastewater (clause 5.4.4): wastewater containing highly toxic, environmentally hazardous, persistent and bioaccumulative pollutants shall be collected and treated separately according to the nature of the chemicals used.
• New disinfectant and parameters (clauses 5.7 and 5.7.3): common disinfectants include chlorine dioxide, sodium hypochlorite, potassium monopersulfate compound, UV and ozone; with potassium monopersulfate, the dose is 5 to 10 mg/L and contact time 1.0 to 1.5 h, or as determined by testing.
• Self-monitoring (clause 6.1.1): self-monitoring shall follow HJ 1105 and others, original monitoring records shall be kept, records of pre-disinfection and disinfection operations shall be properly retained, and monitoring results shall be published. Clause 6.1.2: entities under key permit management shall install and network automatic monitoring equipment per HJ 1105 and others.
• Sampling points (clause 6.2.1): items 16 to 22 of Table 1 and items 15 to 21 of Table 2 are sampled at the outlet of the department-level treatment facility; gross alpha and gross beta radioactivity are sampled at the decay tank outlet; all other pollutants are sampled at the main outlet.

6. Implementation checklist

1. Establish the timeline first: new-build and retrofit projects apply the amendment from 2026-09-01 and existing facilities from 2028-09-01; plan the two tracks separately.
2. Establish the scale: use the 20-bed threshold to apply clause 4.1.2 or clause 4.1.3.
3. Provide separate collection and pre-disinfection for infectious disease areas (clause 4.1.5); otherwise the whole facility is assessed against Table 1.
4. Accept contact time together with residual chlorine: 1.5 h under Table 1 and 1.0 h under Table 2.
5. Apply clause 5.7.1 of the amendment for UV (suspended solids below 10 mg/L, dose not less than 40 mJ/cm2); do not continue to use the 20 mg/L and 60 mJ/cm2 values from HJ 2029-2013.
6. Handle sludge under clause 4.3 of the amendment (disinfect and meet Table 4); the disinfection parameters in clause 6.3.5.1 of HJ 2029-2013 remain usable (lime 15 g/L, pH 11 to 12, contact 30 to 60 min, storage over 7 days; bleaching powder 10% to 15%).
7. For facilities discharging directly, set the zebrafish egg acute toxicity monitoring frequency under clause 6.2.2.5 (at least every six months under key management, at least annually under simplified management).

Limit clauses here are taken from the Amendment to GB 18466-2005 (approved 2026-05-28 by the Ministry of Ecology and Environment and the State Administration for Market Regulation, issued 2026-06-02; effective 2026-09-01 for new, expanded and reconstructed facilities and dual-use infrastructure, and 2028-09-01 for existing facilities). Engineering parameters are from HJ 2029-2013 (effective 2013-07-01, guidance document). Where the amendment and HJ 2029-2013 conflict, the mandatory amendment prevails. For the specific limits in Table 4 of the amendment, refer to the official standard text.