Treatment of waste liquid
Food microbiology laboratory wastewater from cultures with pathogenic bacteria, washing water and other diagnostic test samples. For laboratory wastewater, should be disinfected and sterilized as soon as possible, to prevent the spread of pollution, to strengthen the management of pollution sources.
Waste liquid treatment methods include chemical agent method and thermal disinfection and sterilization method. According to different treatment objects and treatment requirements using different methods of waste liquid treatment.
(A) chemical agent method
Chemical disinfection agent according to its sterilization from strong to weak can be divided into sterilization agent, disinfectant, bacteriostatic agent. Wastewater chemical method of disinfection is best to use the relevant generator, siphon dosing method or high tank dosing method, but also in the wastewater inlet can be directly added. Put liquid chlorine with chlorinator, put chlorine dioxide with chlorine dioxide generator, put sodium hypochlorite with generator or liquid agent, put ozone with ozone generator, put hydrogen peroxide with hydrogen peroxide generator.
(B) physical thermal method
Biosafety laboratory physical thermal method of waste liquid treatment system is through the heating method of continuous disinfection of waste liquid sterilization treatment, the purpose is to make the waste liquid in the shortest possible time to be processed, to avoid causing the spread of pollution.
Continuous disinfection and sterilization of waste liquids is a new technology for sterilizing biological waste liquids, which is mainly applied to the treatment of waste liquids in biosafety laboratories. The waste liquid generated in the laboratory enters the buffer storage tank from the waste liquid inlet through the double drainage pipe, and the waste gas generated is discharged from the permeable pipe after being sterilized by the high-efficiency filter. When the liquid level reaches a certain height, the waste liquid outlet valve opens automatically and the flow rate control pump is started at the same time. The waste liquid is pressed into the pre-heating/cooling cabinet at a set flow rate for pre-heating treatment, and then enters the electrically heated sterilizer, in which the waste liquid is sterilized at high temperature through the electrically heated sterilizing coil. The sterilized waste liquid then enters the pre-heating/cooling cabinet and is cooled by a buffer tube, after which the cooled waste liquid is discharged through a drain. If such treatment is required, it is returned to the tank through the return pipe, or directly processed again continuously. Pre-heating/cooling cabinet through the heat exchanger, so that the high-temperature waste liquid has been sterilized to the incoming waste liquid to be processed for pre-heating, at the same time, their own cooling, in order to save energy. Compared to traditional tank-based sterilization technology, continuous waste liquid sterilization offers significant improvements in terms of efficiency, effectiveness, safety and cost savings.
(C) mixed treatment method
For biosafety laboratories, the experiments of which are more varied and require different treatment of waste liquids, it is suitable for the use of chemical agents and physical thermal mixed method treatment system. This system combines a thermal method continuous waste liquid sterilization system with a chemical agent treatment device, which provides thermal sterilization treatment and chemical agent treatment for waste liquid, and also provides chemical disinfection for pipelines within the sterilization system.
(D) second-stage wastewater treatment system
The second-stage wastewater treatment system can treat the wastewater discharged by the first-stage wastewater treatment system in the biosafety laboratory, and it can also treat the general domestic wastewater from the cafeteria, bathing pools, bathrooms, wash basins, and wastewater discharged in the course of general experiments that do not have pathogenic microorganisms, but contain other chemical pollutants. The second stage wastewater treatment system has the function of effectively removing acid and alkali, heavy metals, organic solvents and killing general microorganisms, so that the treated water quality reaches the standard of discharge or water reuse.
The principle and process flow of the second-stage wastewater treatment system are as follows: wastewater from the biosafety laboratory is de-oiled by the grease trap, and the same as domestic sewage is removed by the grille with a pore diameter of 10mm to remove the larger solids floaters, and then pooled into the conditioning tank for mixing, and then processed by the grille with a diameter of 2mm-5mm to remove solids floaters with a diameter of more than 5mm, and then into the primary sedimentation tank. After precipitation, the supernatant flows into the biochemical treatment pool for biochemical treatment, and then enter the contact pool for final treatment after precipitation in the secondary sedimentation pool, which meets the GB national standard for discharge.
02 exhaust gas treatment
Food microbiology laboratory exhaust, instrumentation (biosafety cabinets, fume hoods, etc.) exhaust will be with pathogenic microorganisms, this exhaust gas, if directly discharged outside the laboratory, will be infected with the crowd and the animals, resulting in epidemics outbreaks, posing a serious threat to human life and health. Therefore, the laboratory exhaust, after strict sterilization before discharge.
The contaminated exhaust of food microbiology laboratory mainly comes from the laboratory air conditioning and ventilation system, biological safety cabinet, negative pressure fume hood, dry/wet heat disinfection sterilizer, centrifuge exhaust hood and other equipment prone to produce bacteria, toxic aerosols of the exhaust, as well as incinerator emission of smoke and dust, etc..
The overall requirements for the installation of air supply and exhaust system of the laboratory is to control the direction of airflow and pressure gradient in the laboratory, so that through the primary, intermediate and high efficiency three-stage filters of the gas flow from the clean area to the contaminated area; indoor use of the upper send down, so that the contaminated area and semi-polluted area of the airflow dead space and vortex to a minimum degree; in particular, it is important to point out, to ensure that the laboratory air can only be through the high-efficiency filters by the Special attention should be paid to ensure that the laboratory air can only be discharged through the high-efficiency filter through the special exhaust duct. The first level of high-efficiency filters should be installed in the front of the laboratory exhaust duct (other ventilation equipment, the same reason). If a second stage of HEPA filters is to be installed, it should be connected in series at a distance of 500 mm behind the first HEPA filter and before the exhaust fan (choose a place where it is easy to maintain, operate and replace, e.g. in the technical mezzanine of the exhaust fan). Installation and replacement of HEPA filters should be secure, airtight and carried out by qualified technicians. Typically HEPA filters should be sterilized prior to replacement, or a location where filter replacement can be performed in an airtight bag should be used. Sitting emergency treatment maintenance personnel should wear protective clothing, the replacement of high-efficiency filters should be immediately sterilized or incinerated. Each high-efficiency filter should be tested after installation, replacement and maintenance, and daily monitoring should be carried out during operation. It should be possible to control the pressure balance and response speed matching between the laboratory exhaust system and other exhaust equipment (biological safety cabinet, negative pressure fume hood, animal negative pressure isolator, centrifuge exhaust hood, etc.) exhaust air. Automatic interlocking devices should be installed to ensure that there is no positive pressure in the laboratory and to ensure that the airflow of other exhaust equipment does not backflow. Exhaust air from the laboratory should be discharged into the air by the exhaust fan after high efficiency filtration. The external exhaust air outlet should be far away from the air supply outlet and set in the downwind direction of the dominant wind, should be at least 2m above the roof of the building in which it is located, and should be designed to protect against rain, rodents, insects, but does not affect the gas discharged directly into the air. In the air supply and exhaust ducts should be installed at the airtight sealing valve, if necessary, can be completely closed for indoor or duct chemical fumigation or cycle disinfection sterilization.
03? Treatment of solid waste
Solid waste refers to human beings in the production, construction, daily life and other activities generated, and to the owner at a certain time and place no longer has the use of value and is discarded solid or semi-solid material.
The Law of the People's Republic of China on the Prevention and Control of Environmental Pollution by Solid Wastes (Decree No. 31 of the President of the People's Republic of China, Dec. 29, 2004) provides for the prevention and control of environmental pollution by industrial solid wastes and domestic garbage, and makes special provisions for the prevention and control of environmental pollution by hazardous wastes.
Solid waste from food microbiology laboratories comes from experimental equipment waste, discarded samples and cultures containing infectious biological factors, discarded infected animals, discarded laboratory air purification materials and so on. Wastes generated in food microbiology laboratories are hazardous wastes that cannot be recycled and must be discarded after sterilization or incinerated and disposed of in landfills. Solid waste can pose a significant threat to human health or the environment due to improper handling, storage, transportation, disposal or negligent management. Polluted wastes should be collected, transported and stored in accordance with the provisions of the Law of the People's Republic of China on Prevention and Control of Solid Waste Pollution of the Environment.
All discarded samples, cultures, and other materials of a biological nature shall be disposed of in specially designed, dedicated, and labeled containers for the disposal of hazardous waste, and stored centrally in a designated location. Prior to removal from the laboratory, they should be processed by autoclaving, chemical disinfection, or other approved techniques, then placed in sealed containers, sorted and labeled, and safely transported out of the laboratory by a designated person. Bio-waste containers should not be filled beyond their design capacity. Sharps (including needles, knives, metal and glass, etc.) should be disposed of directly into ligature-resistant containers. Cultures must be autoclaved at 121 °C for 30 min.
Live specimens on slides should be autoclaved in airtight containers or soaked in 3% Lysol solution or 5% carbolic acid solution for 24 h before disposal. Stained pipette, after use, into 5% coal phenol soap solution or carbolic acid solution, at least 24 h (disinfection liquid shall not be lower than the height of the immersion) and then autoclaved at 121 ℃ for 30 min. Smear staining rinsing liquid, generally can be directly flushed into the sewer, the pathogenic rinsing liquid must be flushed in a beaker, after autoclaving before being poured into the sewer. The slides or dishes used for agglutination tests must be autoclaved before washing. Broken cultures, immediately spray and soak the contaminated parts with 5% coal phenol soap solution or carbolic acid solution, soak for 30 min and then wipe clean. Contaminated overalls or overalls worn for pathogenic bacteria testing, non-disposable lab caps and masks, etc., should be placed in a special disinfection bag and autoclaved before washing.
The laboratory should ensure that hazardous waste is handled by properly trained personnel using appropriate personal protective equipment and devices. Accumulation of garbage and accumulation of laboratory waste shall not be permitted, and filled containers shall be promptly closed and stored in a designated safe place usually within the laboratory area until decontamination or final disposal. Answers from