When washing porcelain or clothes with water containing heavy metals, brown marks will appear.
Boil the water, then drink it, and feel carefully whether there is any odor in the water during drinking. Whether there is astringency. If there is, it means that the water quality is high in hardness.
Pick up the water under the tap with a cup and smell whether there is bleach in the water. If so, your tap water may contain residual chlorine.
Use transparent containers, unprinted glasses and disposable plastic cups. Fill a glass of water, leave it for a few hours and observe it carefully in a well-lit place to see if there is suspended matter in the water. If so, it is recommended to handle it.
Comparison of three common treatment methods
A, lime neutralization method
The basic principle of 1. 1
Lime neutralization reaction method is to add hydrated lime C a( O H) to wastewater containing heavy metal ions, so that it can react with heavy metal ions in water to generate heavy metal hydroxide with small ion solubility product. The P H value in water is controlled within a certain range by the dosage, so that the ion concentration product of heavy metal hydroxide in water is greater than its ion solubility product, and heavy metal hydroxide precipitates, thus achieving the purpose of removing heavy metal ions and purifying wastewater. The waste water is collected into the waste water homogenization regulating tank, and the mixed waste water is sent to the first-stage neutralization tank by a corrosion-resistant self-priming pump. Ferrous sulfate solution is added to the pipeline as an arsenic precipitation agent (the addition amount is Fe/As= 10), and lime milk is added for full stirring reaction for 30 min. The addition amount of lime milk is automatically controlled by a pH meter to make the pH value of the solution at the outlet of the first-stage neutralization tank. In order to make ferrous iron oxidized to ferric iron to produce flocculation, an oxidation tank is arranged behind the primary neutralization tank for aeration oxidation, and the oxidized wastewater flows to the secondary neutralization tank by itself, and then lime milk is added, and the dosage of lime milk is automatically controlled by a pH meter, so that the pH value at the outlet of the secondary neutralization tank is 9 ~11; Coagulant No.3 (concentration: 10 mg/L) is added to the wastewater outlet of the secondary neutralization tank, and the treated wastewater flows into a thickener for flocculation and precipitation; Supernatant flows into the clarifier by itself. The traditional lime neutralization process for treating heavy metal wastewater is to neutralize with lime first, and then with sodium hydroxide. The removal rate of various heavy metals varies with pH, and the solubility products of different metals vary with pH. The same pH has different precipitation effects on heavy metals, and there are usually more than one kind of heavy metals in wastewater. According to the content of heavy metals, when the solubility product of metals is the highest at a lower ph value, the mixture is adjusted to the corresponding pH value, and lime milk is added for neutralization reaction to precipitate most metals in wastewater. The supernatant enters the next stage of regulating pool to adjust PH, and the second stage of neutralizing reaction pool is used to remove the remaining heavy metal ions.
Advantages and disadvantages of 1.2 lime neutralization precipitation method
Using limestone as neutralizer has strong adaptability, and also has the advantages of short wastewater treatment process, simple equipment, low price, low wastewater treatment cost, low water content of slag, easy dehydration and so on. However, after the wastewater is neutralized with lime, the heavy metal hydroxide alum flower has a small specific gravity and is easily broken into small particles when it is strongly stirred or transported, so the settling speed is slow. In the process of precipitation and separation, it often overflows with the water flow, which makes the turbidity of treated wastewater increase and heavy metal ions still exceed the standard. It is required that the wastewater does not contain complexing agents such as C N-I and N H, otherwise the heavy metal ions in the water will react with complexing agents to generate complex and stable complexing ions with heavy metal ions as the center ions and complexing agents as ligands, which makes the wastewater treatment complicated and difficult. The precipitated alum flower and sludge have extremely high water content (above 99%) and poor filtration and dehydration performance. In addition, the complex composition and low grade of heavy metals bring difficulties to comprehensive recovery and disposal, and even cause secondary pollution. In addition, a large amount of slag is not conducive to the recovery of valuable metals, and it is also easy to cause secondary pollution II. Treatment of heavy metal wastewater with lime water. Because different heavy metals have different combinations with OH at the same PH, the solubility products of the same metal at different PH are also different. Therefore, it is obviously not feasible to treat complex wastewater containing more heavy metals with traditional lime method. One is that some heavy metals can't meet the discharge standard, and the other is that the treated wastewater contains more calcium. In smelters, it is difficult to recycle.
Second, sulfide precipitation method
2. 1 Basic principles
Sulfide agent is added into wastewater containing heavy metal ions, which reacts with heavy metal ions in water to generate sulfide with very small ion solubility product. By adding the agent, the ion solubility product of heavy metal sulfide in water is controlled to be larger than that of heavy metal ions, so that metal ions in wastewater are precipitated or selectively precipitated. Then, polymer collectors are added, and a large number of dense fine bubbles are introduced into wastewater to make them adhere to each other. A floating body with an overall specific gravity less than that of water is formed, and the sediment floats to the water surface under the action of buoyancy, so that sulfide in the water is precipitated, solid-liquid separation is realized, and the effects of removing heavy metals and purifying water quality are achieved. Commonly used vulcanizing agents are sodium sulfide, sodium sulfide, H2S, sodium sulfide and ferrous sulfide.
three
3. 1 Basic principles
Biological agents are excellent strains screened from nature or efficient strains produced by gene combination technology. They are highly effective bioactive microbial preparations made by advanced biotechnology and special production technology. The composition of biological agents can be summarized as microorganisms, enzymes and some substances that maintain microbial activity. The components of the metabolites of the compound functional flora mainly composed of thiobacillus and other compounds were designed. Biological preparations containing a large number of functional groups such as hydroxyl, sulfhydryl, carboxyl and amino groups were prepared by group grafting technology. Firstly, biological agents are used to deeply remove heavy metal ions from wastewater, and decalcifying agents and flocculants are added. After solid-liquid separation, the clear liquid from which heavy metal ions and calcium ions are removed is treated by a membrane treatment device to remove chloride ions in the wastewater, so that the treated sewage can meet the water quality requirements for reuse.
3.2 Advantages of biological agents
The biological preparation method of heavy metal wastewater solves the shortcoming that it is difficult for chemical agents to deeply purify polymetallic ions at the same time. Advanced treatment and recycling technology of biological agents can simultaneously and efficiently remove heavy metal ions such as cadmium, arsenic, lead, zinc, mercury and copper, and the concentration of each heavy metal ion after treatment is lower than the Discharge Standard for Pollutants in Lead and Zinc Industry (GB 25466-2010). At the same time, the biological preparation has the functions of efficient flocculation and synergistic decalcification, and the calcium ion can be controlled to be removed below 50 mg/L, and the treated low-calcium purified water can be reused on a large scale. The advantages of biological agents are: (1) can shorten the time of microbial culture and domestication, and quickly increase the concentration of microorganisms in the biological treatment system, thus improving the work efficiency; (2) Natural microorganisms contained in biological agents do not contain pathogenic bacteria and pathogens. Catalyzed by enzymes, these microorganisms feed on organic nutrients in sewage. After sewage purification, these microorganisms will gradually decrease with the decrease of pollutants until they become extinct, and will not cause secondary pollution; (3) Safe use, simple operation, basically no need to increase equipment or engineering, saving energy and capital investment. (4) Strong resistance to heavy metal impact load, high purification efficiency and stable operation: for wastewater with large and irregular concentration fluctuation, the heavy metals in the purified water treated by the new process are lower than or close to the water quality standard of drinking water source; (5) The controllable removal effect of calcium ions in wastewater is obvious, which can be controlled below 20mg/L, and the reuse rate of purified water is over 95%; (6) COD and SS of the purified water meet the first-class discharge standard. (7) The separation effect of slag and water is good, the effluent is clear, the water quality is stable, the amount of hydrolyzed slag is less than that of neutralization method, and the content of heavy metals is high, which is beneficial to resource utilization. (8) For 100-300mg/L heavy metal wastewater, the cost of biological preparation is 0.3-0.8 yuan/m3; (9) The treatment facilities are all conventional facilities, with small floor space, low investment and construction costs and mature technology. For the existing lime neutralization treatment system, only the biological agent storage tank and the agent dosing pump need to be added, and the transformation cost is low.