1.Key points for selecting industrial-grade products

(1)Wastewater treatment

Purity requirements: Select industrial-grade ferrous sulfate (purity>95%), give priority to titanium dioxide byproducts (low cost, containing a small amount of impurities), for flocculation, decolorization and heavy metal precipitation.

Process adaptation: It is necessary to use oxidation technology (such as aeration) to convert ferrous iron into trivalent iron to improve flocculation efficiency: Adjust the wastewater pH to 9-11 before adding to ensure the reaction effect.

(2) Chemical manufacturing

High purity requirements: Anhydrous ferrous sulfate (FeSO>98%), low impurity content (water insoluble matter ≤0.5%), used in the production of iron salts, dyes, etc., to avoid interference with chemical reactions.

(3) Environmental certification

Prioritize products that have passed ROHS or ISO certification to ensure that there is no heavy metal residue after wastewater treatment to avoid secondary pollution.

2. Key points for selecting agricultural-grade products

(1) Iron supplementation to prevent yellowing

Purity and safety: Agricultural-grade ferrous sulfate needs heavy metals. (Lead, arsenic) content complies with the "Fertilizer Safety Standard" (GB 38400-2019), purity> 90%, to avoid soil pollution.

Chelation enhancement: Prioritize products compounded with citric acid or chelating agents (such as slow-release type) to prevent iron ion oxidation failure and extend the fertilizer effect cycle.

(2) Soil improvement

Acidity adjustment: Choose granules containing free acid (pH3-4), which can reduce the pH of alkaline soil to 5.5-6.5 and promote nutrient absorption by acid-loving plants (azalea, camellia)

(3) Application method adaptation

Foliar spraying: Choose ferrous sulfate heptahydrate (easily soluble in water) with a concentration of 0.1%-0.3%, and use it immediately to prevent oxidation

Drip irrigation/basal fertilizer: Granules need to be mixed with organic fertilizer to enhance soil fertilizer retention, and avoid mixing with alkaline such as wood ash

3. General precautions for industry and agriculture

(1) Form and storage

Industrial drying type is suitable for long-term storage; agricultural heptahydrate needs to be sealed and moisture-proof, and oxidation to trivalent iron after moisture will reduce effectiveness

(2) Safety protection

Wear protective gloves when using industrially to avoid direct contact with the skin; after agricultural spraying, the equipment needs to be cleaned to prevent residual corrosion

(3) Environmental protection and economy

Agriculture recommends the combination of "soil improvement + foliar spraying", with a dosage of 5-10 grams per mu. Excessive use can easily lead to acidification or iron poisoning. Industry prioritizes by-products to reduce costs, but the impact of impurities needs to be monitored.