Cal. Health & Safety Code § 25123.5

(a) Except as provided in subdivisions (b) and (c), “treatment” means any method, technique, or process which is not otherwise excluded from the definition of treatment by this chapter and which is designed to change the physical, chemical, or biological character or composition of any hazardous waste or any material contained therein, or which removes or reduces its harmful properties or characteristics for any purpose.
(b)
1. (1) “Treatment” does not include any of the activities listed in paragraph (2), if one of the following requirements is met:
  1. (A) The activity is conducted onsite in accordance with the requirements of this chapter and the department’s regulations adopted pursuant to this chapter governing the generation and accumulation of hazardous waste.
  2. (B) The activity is conducted in accordance with the conditions specified in a permit issued by the department for the storage of hazardous waste.
2. (2) The activities subject to the exemption specified in paragraph (1) include all of the following:
  1. (A) Sieving or filtering liquid hazardous waste to remove solid fractions, without added heat, chemicals, or pressure, as the waste is added to or removed from a storage or accumulation tank or container. For purposes of this subparagraph, sieving or filtering does not include adsorption, reverse osmosis, or ultrafiltration.
  2. (B) Phase separation of hazardous waste during storage or accumulation in tanks or containers, if the separation is unaided by the addition of heat or chemicals. If the phase separation occurs at a commercial offsite permitted storage facility, all phases of the hazardous waste shall be managed as hazardous waste after separation.
  3. (C) Combining two or more waste streams that are not incompatible into a single tank or container if both of the following conditions apply:
    1. (i) The waste streams are being combined solely for the purpose of consolidated accumulation or storage or consolidated offsite shipment, and they are not being combined to meet a fuel specification or to otherwise be chemically or physically prepared to be treated, burned for energy value, or incinerated.
    2. (ii) The combined waste stream is managed in compliance with the most stringent of the regulatory requirements applicable to each individual waste stream.
  4. (D) Evaporation of water from hazardous wastes in tanks or containers, such as breathing and evaporation through vents and floating roofs, without the addition of pressure, chemicals, or heat other than sunlight or ambient room lighting or heating.
3. (3) This subdivision does not apply to any activity for which a hazardous waste facilities permit for treatment is required under the federal act.
(c) “Treatment” does not include the combination of glutaraldehyde or orthophthalaldehyde, which is used by medical facilities to disinfect medical devices, with formulations containing glycine as the sole active chemical, if the process is carried out onsite.