The main factors affecting the new iron-carbon activated coke in wastewater treatment are as follows:
The first is the influence of the pH value of the wastewater.
The pH value of the wastewater (hydrogen ion concentration index) directly affects the corrosion rate of iron in the iron-carbon active coke and the amount of Fe(OH)2 having flocculation. The corrosion rate of iron varies with different pH values. The corrosion rate of iron is the fastest when the pH is 2~4, and the corrosion rate is stable when the pH is 5~9. When the alkalinity is strong, the corrosion rate decreases with the increase of pH value; when the alkali is extremely strong, the corrosion rate will increase again.
According to the basic principle of iron-carbon microelectrolysis, the number of ions participating in the reaction of the primary battery and the product change due to the change of pH value: when the pH value is high, the number of H+ participating in the reaction is insufficient, and the reaction of Fe being oxidized to Fe2+ is suppressed; pH value At lower temperatures, the Fe/C microelectrolysis reaction can be accelerated, but the formation of floes with Fe2+ as the gelation center is destroyed.
From the analysis of existing engineering and experimental data, the pH value is controlled at 5~6.5, which is the best in effect and economy. In the treatment of some special hard-to-degrade wastewater, the appropriate reduction of pH value will increase the COD removal rate. When the pH value is reduced to below 3, the iron loss in the activated coke is faster, which affects the treatment effect.
The second is the impact of the iron-carbon mass ratio.
The iron-carbon and carbon in the new iron-carbon active coke constitute a micro-electrolysis cell. As the reaction progresses, the iron is gradually corroded in the active coke, and the content is lowered. When the iron content in the active coke is low, the micro-electrolysis is weakened, and more manifests as the adsorption of the activated coke. Increasing the iron content increases the number of galvanic cells in the system and improves the removal effect of the organic matter. However, when the iron particles are excessive, the mechanical strength of the activated coke is lowered, and the electrode reaction of the primary battery is suppressed, and the cost of the treatment is also increased. Therefore, in the preparation of iron-carbon activated coke, the duration of micro-electrolysis reaction, the strength of micro-electrolysis, the mechanical strength of activated coke, etc. should be considered comprehensively, and the appropriate iron-carbon ratio should be selected.
The third is the impact of reaction time.
In the actual treatment process, the longer the reaction time, the better, but the reaction time is related to the change of pH value during the treatment, in addition to the content of iron in the active coke. As the reaction proceeds, the acidity of the entire activated coke packed column will decrease, indirectly affecting the subsequent flocculation and precipitation process. With the weakening of micro-electrolysis, the adsorption of activated coke is more prominent, and the dynamic packed column should be used in practical applications.
In addition to the above factors, wastewater treatment efficiency is also affected by factors such as aeration volume and H2O2 oxidant. In order to improve treatment efficiency, various influencing factors should be considered comprehensively.
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