Since the biological oxidation process of organic matter in water is related to the temperature of water and the time of oxidation, the determination of biochemical oxygen demand is carried out according to the specified water temperature and time. Generally, the collected water sample is diluted to an appropriate ratio and sealed at a water temperature of 20 °C. After culturing for 5 days, the amount of dissolved oxygen consumed for 5 days was determined, and the biochemical oxygen demand (BOD5) was determined by the following formula.
Biochemical oxygen demand refers to the amount of oxygen required for the decomposition of organic matter in water into a stable state under the action of aerobic bacteria, in mg/L. Biochemical oxygen demand is not only an indicator of the degree of organic pollution in water, but also an important parameter for determining the volume and operation management of water treatment equipment. The larger the value, the more serious the pollution.
Shell activated carbon is widely used in deep purification of drinking water, industrial water and wastewater, industrial water purification and gas phase adsorption, such as power plants, petrochemicals, oil refineries, food and beverage, sugar making, medicine, electronics, fish farming, shipping The water purification treatment of the industry can effectively adsorb free chlorine, phenol, sulfur and other organic pollutants in the water, especially the precursor substances of the mutant (THM), to purify and remove impurities and odor. It can also be used for industrial exhaust gas purification, gas desulfurization, petroleum catalytic reforming, gas separation, pressure swing adsorption, air drying, food preservation, gas mask, solvent carrier, industrial solvent filtration, decolorization and purification. Separation, purification, purification of various gases; recovery of organic solvents; decolorization, deodorization, refining of sugar, monosodium glutamate, medicine, alcohol, beverages; refining of precious metals; catalysts and catalyst carriers in the chemical industry. The product has more functions of decolorization, purification, impurity removal, deodorization, odor removal, carrier, purification and recovery.
Mainly used for food, beverage, purified water filtration, power plant boiler wastewater treatment, domestic water and industrial water dechlorination, odor removal and liquid filtration, environmentally friendly activated carbon, can effectively toxic substances such as phenol, mercury, lead, arsenic and heavy metals in water.
Where D1 is the mass concentration of dissolved oxygen before the increase or decrease of the diluted water sample, mg/L;
D2——the mass concentration of dissolved oxygen in the diluted water sample after 5 days of culture, mg/L;
B1——the mass concentration of dissolved oxygen before dilution in culture, mg/L;
B2——the mass concentration of dissolved oxygen after 5 days of dilution water, mg/L;
F1——the proportion of dilution water in the culture solution, %;
F2——the proportion of water sample in the culture solution, %;
[In the determination of biochemical oxygen demand, the following matters should be noted:]
1. Must contain micronutrients for biological reproduction. Low price, quality assurance, after-sales service home, is a wise choice for new and old customers, your satisfaction, my honor...,, welcome to inquire, a cooperation, lifelong friends!
2. The dissolved oxygen must be brought close to the helium state, because the dissolved oxygen is too small, the biochemical reaction cannot be fully performed, and the supersaturation is likely to cause measurement errors.
3. Grasp the appropriate dilution rate of water sample, otherwise it will affect the accuracy of the measured value. Generally, the same water sample is diluted into several different dilution factors.
4. Since the biochemical reaction is utilized for the measurement, the dilution water in the culture must have a certain biological phase. When there is no organism or bacteria in the wastewater, it must be inoculated with river water or sewage;
5. There must be no harmful substances that hinder the reproduction of the organism.
[Adsorption adsorption of activated carbon (moving bed / pulsating bed decolorizing device system)]
Activated carbon is a kind of microcrystalline carbon material made of carbon-containing material with black appearance, developed internal pore structure, large specific surface area and strong adsorption capacity. There are a large number of micropores in the activated carbon material that are invisible to the naked eye. Granular activated carbon has innumerable internal micropores and therefore has a large surface area, so that activated carbon has excellent adsorption properties for organic matter.
In the particulate carbon adsorption device, the sugar liquid is brought into contact with the granular carbon bed in a countercurrent direction. Generally, the sugar liquid is injected from the bottom of the adsorber by a pump and flows upward through the GAC bed, and the decolorized sugar liquid finally leaves the top of the adsorber. According to the requirement of decolorization rate, a part of the particulate carbon which has reached saturation state is taken out from the adsorber by pulse operation at intervals, and a corresponding amount of new carbon is added from the top of the adsorber. This operation procedure and process are called Pulsating operation. In addition to the period of the pulse operation, the flow of the sugar liquid in the adsorber is continuously performed, and the operation of removing, regenerating, and recycling the saturated carbon is also continuously performed. This overall operating technology system is referred to as the "pulsating bed (moving bed) GAC decolorization technology system."
Granular activated carbon is widely used in liquid phase applications such as food refining, medicine, chemicals, water treatment, and advanced wastewater treatment. Some large-sized activated carbon can also be used in the field of gas phase adsorption or purification such as solvent recovery and waste gas treatment. Activated carbon adsorption decolorization technology has become an important technology in the purification of sugar liquid in the sugar industry.
[Use of activated carbon in purification bath]
Activated carbon is a porous structural substance, which is obtained by impregnating raw materials with chlorides and acids, then carbonizing at low temperature, then burning and activating or purifying pure carbon in a gaseous medium at a high temperature. The powder surface area of ​​1g activated carbon is as high as 500-1500m2, and has excellent adsorption performance. In the purification of various plating solutions, its main role is to remove oils, organic impurities and decomposition products of various additives. The following points should be noted when using activated carbon to purify the bath:
1) Select a suitable activated carbon product. The activated carbons on the market are granulated and powdery. It is convenient to use granular activated carbon for filtration, but the treatment effect is far less than that of powdered activated carbon. The reason is that the powder has a much larger specific surface area than the granular one. Choose according to the degree of contamination of the plating solution.
2) Activated carbon should contain no impurity ions harmful to the plating solution. At present, the raw materials for the manufacture of activated carbon are mainly the shells of wood, coal and hard shell nuts (such as coconut). Practice has proved that in the purification of plating solution, activated carbon made from hard husks is superior to activated carbon products made from coal. Inferior activated carbon often contains more impurities such as zinc and should not be used. If activated carbon containing zinc impurities is used in the purification of nickel plating liquid, it will cause more serious pollution results (such cases are not uncommon).
3) The dosage should be sufficient. For plating solutions with different levels of organic impurities, appropriate input should be taken, generally 2~5g/L. If the dosage is insufficient, the treatment effect is not good. The amount of activated carbon can also be determined by a small test using a small process test tank or a Hull tank.
4) The θ and pH of the treated bath should be appropriate. Most of the plating solutions have a good treatment effect with a θ of 55 to 70 ° C and a pH of 5 to 6. θ and pH should remain stable throughout the treatment.
5) Stirring should be sufficient and uniform. It is advisable to use intermittent filtration and compressed air for intermittent strong agitation. If manual agitation is used, it should be carried out continuously in the plating tank without leaving a dead angle. t stirring should generally be 2 ~ 4h.
6) Rest time. After the adsorption process is completed, the plating solution should be allowed to stand for a period of time and then filtered, t is still for 6 to 12 hours; after sufficient precipitation, it is filtered 2 to 3 times until there is no residual carbon powder in the plating solution, and the plating solution is in bulk color (none Charcoal black) so far.
7) Prevent detachment. When the activated carbon is continuously filtered by the electroplating process, when the activated carbon is saturated, the activated carbon in the filter element should be cleaned and replaced in time to prevent desorption and impurities from re-contaminating the plating solution.
[How to distinguish between coconut shell activated carbon and other activated carbon]
Why is coconut shell activated carbon more expensive than other activated carbon? This is a question for the general customers. In fact, the coconut shell activated carbon has the following reasons:
First, the raw materials are expensive: coconut shell activated carbon is imported from high quality coconut shells from Vietnam, Indonesia, Philippines and other countries. The peak activated carbon is refined by scientific formula and using the world's advanced American technology rotary high temperature activation furnace.
Second, the cost performance is high: coconut shell activated carbon has high iodine value, developed pores, large adsorption capacity, fast decolorization and deodorization, high product strength and long service life.
[Simple separation method between coconut shell activated carbon and other activated carbon]
1. Coconut shell activated carbon belongs to the category of shell-shell activated carbon. Its main features are low density and light hand feeling. The weight in the hand is obviously lighter than that of coal-based activated carbon. The same weight of activated carbon, coconut shell activated carbon volume is generally larger than coal-based activated carbon.
2, coconut shell activated carbon shape is generally broken granular, flake, and molded activated carbon, such as columnar, spherical activated carbon, mostly coal charcoal.
3. Due to the low density of coconut shell activated carbon and light hand feeling, the activated carbon can be put into the water. The coal charcoal generally sinks faster, while the coconut shell activated carbon floats in the water for a longer period of time. If you add more weight, you will gradually sink into the bottom of the water. When the activated carbon is completely bottomed, you will see that each activated carbon is wrapped with a small bubble on the outside, which is crystal clear and very interesting.
4, coconut shell activated carbon is a small molecular pore structure, the activated carbon is placed in the water, the air discharged when the water molecules are adsorbed will produce many very small blisters (the naked eye can just see), densely floating to the surface. Coal-based activated carbon is generally.
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