Electrochemical wastewater treatment equipment for pesticide and chemical

Product Specification

I. Product Overview

Pesticide chemical wastewater is recognized as one of the most difficult industrial wastewaters to treat. It originates from the synthesis of pesticide active ingredients (herbicides, insecticides, fungicides, plant growth regulators, etc.), intermediate production, and formulation processing. Its water quality characteristics are extremely complex and severe: the wastewater has extremely high organic matter concentrations (COD is typically 5000~50000 mg/L, with some mother liquor reaching over 100000 mg/L), contains a large number of recalcitrant and highly biotoxic pollutants (organophosphates, organochlorines, pyrethroids, triazines, nitrogen‑rich agro‑chemical components, heterocyclic compounds, nitrobenzenes, phenoxycarboxylic acids, etc.), often contains high concentrations of salts (Cl⁻, SO₄²⁻, PO₄³⁻, Na⁺, etc., TDS 3%~15%), contains large amounts of organic solvents (methanol, dichloromethane,typical aromatic components, xylene, DMF, etc.), has extremely low BOD₅/COD ratios (0.02~0.10), exhibits extremely poor biodegradability, contains phosphorus (a characteristic pollutant of organophosphate pesticides), and the water quality and quantity fluctuate drastically with product seasons and batch changes.

The treatment of pesticide and chemical wastewater has long been a major bottleneck in the industry, with the core Key difficulties being: Highly toxic to organisms—organophosphates, organochlorines, pyrethroids, and other pesticides have a strong killing or inhibitory effect on activated sludge microorganisms (their designed purpose is to kill pests/pathogens/weeds). When the biological system comes into direct contact with the raw water, a large number of microorganisms can die within hours to days. High salinity further inhibits biological processes and can even paralyze the system—pesticide synthesis involves extensive use of acid-base neutralization and salting-out processes, resulting in wastewater salinity of 5% to 15%. The high osmotic pressure directly leads to the death of activated sludge microorganisms. Strong seasonality and batch-specificity of products, leading to drastic changes in wastewater quality—pesticide production is highly seasonal (concentrated production before spring planting). When switching between different products, the COD and types of toxic substances in the wastewater change simultaneously, and the biological system cannot adapt quickly. Difficulty in achieving standards through advanced treatment—the COD of the effluent after biological treatment usually contains residual organic phosphorus and persistent organic matter, and conventional advanced treatment methods are unable to stably reduce it to the discharge standard. This system adopts electrochemical oxidation technology, utilizing direct anodic oxidation and electrocatalysis. The synergistic effect of the generated hydroxyl radicals (·OH) and strong oxides such as active chlorine precisely targets the chemical structure of characteristic pollutants in pesticide wastewater:

Organochlorines: C-Cl bonds are oxidized and broken, chloride ions are removed in the form of Cl⁻, the organic structure undergoes ring-opening degradation, and biotoxicity is eliminated.

Pyrethroids: Ester bonds and cyclopropane structures are oxidized and broken, and the insecticidal active groups are deactivated.

Triazines (such as atrazine): The triazine ring is oxidized and opened on the anolyte surface, significantly reducing biotoxicity.

Nitrobenzenes and phenoxycarboxylic acids: Aromatic... Rings are oxidized and opened, nitro groups are removed, and the compounds are converted into biodegradable small molecules. Heterocyclic compounds: N/S/O heterocyclic rings are oxidized and opened, eliminating toxicity. Ammonia nitrogen and total phosphorus: Ammonia nitrogen is oxidized to N₂ by active chlorine and removed; organic phosphorus is converted to orthophosphate and can be removed by electrocoagulation and synergistic precipitation or subsequent chemical precipitation. The treated effluent B/C ratio is significantly increased from 0.02-0.08 to over 0.30, biotoxicity is reduced from >90% to <20%, and COD is significantly reduced, creating safe and biodegradable influent conditions for subsequent biological systems. For biological effluent, electrochemical deep treatment fully meets all discharge standards for COD and color.

The entire process consumes only electricity, without adding any chemical agents, and does not produce hazardous waste such as iron sludge or saturated carbon. The electrodes are adaptable to complex pesticide wastewater conditions containing high salt, oil, and organic solvents, and operate safely at normal temperature and pressure. By rapidly adjusting the current, it can respond to drastic fluctuations in water quality caused by switching pesticide products within minutes, without the need for the long acclimatization and waiting period of traditional biochemical systems. It is a key technical solution to address the four core Key difficulties of pesticide wastewater: "high toxicity, difficult degradation, high salinity, and large fluctuations".

II. Difficulties in treating pesticide and chemical wastewater and solutions with this equipment

III. Working Principle

After being screened, settled, or filtered to remove suspended solids, pesticide chemical wastewater enters an electrochemical reactor, where the following core reactions occur under the action of electrodes:

(1) Oxidation of the characteristic structure of organophosphorus pesticides (core function)

Organophosphorus pesticides (glyphosate, chlorpyrifos, malathion, dimethoate, dichlorvos, etc.) are the most representative pollutants in pesticide wastewater. Their biotoxicity and total phosphorus compliance problems stem from the stability of P-C and P-S bonds:

Glyphosate (PMIDA): (HO)₂P(=O)—CH₂—NH—CH₂—COOH, the P-C bond is oxidized and broken on the anode surface, and the organophosphorus is converted into orthophosphate (PO₄³⁻)

Chlorpyrifos (O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl)thiophosphate): P-S and P-O bonds are broken, the pyridine ring is opened, and the chlorine atom is removed

(2) Dechlorination and ring opening of organochlorine pesticides

Organochlorine pesticides The C-Cl bond and aromatic ring of the pesticide are the sources of toxicity and recalcitrant degradation:

The C-Cl bond breaks at the anode surface, and chlorine is removed in the form of Cl⁻.

The dechlorinated aromatic ring is attacked and opened by hydroxyl radicals, transforming into small molecule organic acids.

Finally, it is mineralized into CO₂ and H₂O.

(3) Deactivation of active groups in pyrethroids and other pesticides

The ester bond is oxidized and broken, resulting in loss of insecticidal activity.

The cyclopropane structure is oxidized and opened.

The triazine ring (atrazine, etc.) is oxidized and opened at the anode surface, releasing N as NH₃/N₂.

Nitrobenzenes: Nitrate removal + benzene ring opening.

Heterocyclic compounds (pyridine, pyrimidine, thiazole, etc.): Heterocyclic ring opening, eliminating biotoxicity.

(4) Direct electro-oxidation (organic skeleton mineralization)

The organic skeleton (aromatic ring, heterocyclic ring, long carbon chain, etc.) in the pesticide molecule directly loses electrons and is oxidized at the anode surface. The macromolecules gradually decompose into small molecule organic acids, and finally mineralize into CO₂ and H₂O.

(5) Indirect Electro-oxidation (·OH and Broad-Spectrum Oxidation with Activated Chlorine): Hydroxyl radicals (·OH) are generated by anolysing water. Simultaneously, the naturally occurring high concentration of chloride ions in the wastewater (pesticide wastewater commonly contains Cl⁻, with concentrations typically between 3000 and 20000 mg/L) are electrolyzed to generate activated chlorine (Cl₂, HOCl, OCl⁻), supplementing the oxidation of pollutants in the solution that did not directly contact the anode.

(6) Ammonia Nitrogen Removal: Activated chlorine oxidizes ammonia nitrogen to nitrogen gas (2NH₃ + 3HOCl → N₂ + 3Cl⁻ + 3H₂O), achieving a removal rate of 80%–95%.

IV. Core Advantages (Targeting Pesticide and Chemical Wastewater)

V. Technical Parameters (Customizable)

VI. Process Location

Option 1: Pretreatment and Detoxification

Pesticide wastewater (raw water/combined water) → Bar screen/equalization tank → Sedimentation/flotation (SS and oil removal) → Electrochemical treatment equipment (organophosphorus conversion/organochlorine dechlorination/heterocyclic ring opening/toxicity elimination/B/C enhancement) → Intermediate tank/buffer tank → Biological system (hydrolysis acidification + A/O or A²/O) → Total phosphorus precipitation (chemical phosphorus removal) → Discharge meeting standards

Note: The electrochemical detoxification unit is an irreplaceable core guarantee for the pre-biological treatment of pesticide wastewater. Pesticide wastewater that has not undergone electrochemical detoxification and is directly fed into the biological treatment system will cause the death of a large number of microorganisms within hours to days due to its high toxicity. The electrochemical stage completes the conversion of organic phosphorus to orthophosphate, dechlorination of organochlorine, heterocyclic ring opening, toxicity elimination, and B/C enhancement, with a total phosphorus conversion rate ≥85%~95%; effluent B/C ≥0.30, and the COD removal rate of the biological stage is increased by 50%~80%. After electrochemical detoxification, the effluent is treated by a biological system, and total phosphorus is reduced to standard through subsequent chemical precipitation (addition of lime/iron salts/aluminum salts).

Option 2: High-Concentration Mother Liquor Reduction

High-concentration pesticide mother liquor (containing high-concentration technical grade pesticides and organic solvents) → Collection tank → Electrochemical treatment equipment (COD removal rate 50%~80%) → Effluent flows into the plant's integrated wastewater system → Conventional treatment

Explanation: Traditionally, high-concentration mother liquor generated during pesticide synthesis is disposed of as hazardous waste through off-site incineration, which is extremely costly. Electrochemical treatment allows for on-site batch processing of this type of high-concentration mother liquor—significantly reducing COD and toxicity while efficiently converting organic phosphorus into orthophosphate—and ensuring a stable flow into the plant's integrated wastewater system. This reduces hazardous waste incineration/off-site transportation by 70%~90%, resulting in substantial annual savings in disposal costs.

Option 3: Advanced Biological Treatment of Effluent (Upgrading and Compliance with Standards)

Pesticide Wastewater → Pretreatment → Biological System → Secondary Sedimentation Tank → Electrochemical Advanced Treatment Unit (Removal of Residual Stubborn COD, Organophosphorus Residue, and Color) → Discharge Meeting Standards