FAQ

1. Check if all instruments are working properly and stably, paying special attention to whether the ammeter exceeds the rated current of the motor. If the current is too high or too low, stop the machine immediately for inspection.

2. Check if the flow rate of the water pump is normal. When installing a flowmeter, check if the flow rate indicated by the flowmeter is normal or estimate the flow rate based on the current of the ammeter, the flow rate of the outlet pipe, and the change in the water level of the collection well.

3. Check if the packing pressure plate of the water pump is heating up and if the dripping is normal.

4. Pay attention to the sound and vibration of the unit.

5. Pay attention to the temperature rise of the bearing, generally not exceeding 35 ℃ of the surrounding ambient temperature.

6. Check the temperature rise of the motor, and if it is too high, stop the vehicle for inspection.

7. Check whether the water pump and pipeline are leaking.

8. Check if the water level in the collection well is too low and if the grille or inlet is blocked.

Step 1: Equalization Tank

Wastewater from electronics and semiconductor manufacturing flows by gravity into an equalization tank. This step helps balance both water quality and flow rate, ensuring stable performance in subsequent treatment stages and reducing shock loading.

Step 2: Physicochemical Pretreatment System

The wastewater enters a physicochemical pretreatment system where fine, dispersed microbubbles are introduced. These bubbles attach to hydrophobic solids and liquid particles, forming a three-phase mixture. This allows lighter flocs to rise to the surface, forming a layer of sludge that is removed, achieving solid-liquid separation. The treated water then flows to an intermediate tank.

Step 3: Biological Treatment System

The wastewater is directed into a hydrolysis acidification tank. Here, anaerobic bacteria break down hard-to-degrade organic matter through hydrolysis and acidification. This step improves biodegradability and prepares the wastewater 

Step 1: Equalization Tank

High-saline wastewater, such as cleaning water and mixed-bed regenerant from production workshops, flows by gravity into a high-salinity equalization tank. Here, the water quality is homogenized. The wastewater is then pumped into a coagulation tank for pH adjustment. An online pH controller automatically regulates the dosing of PAC (Polyaluminum Chloride).

Step 2: Dissolved Air Flotation (DAF) System

This process introduces fine microbubbles into the water, which attach to suspended particles forming a three-phase system (water-air-solid). These aggregates float to the surface due to their lower density, where a skimmer removes the sludge layer, achieving solid-liquid separation.

Step 3: Filtration System

The high-salinity wastewater then enters a disc filtration system, where both disc filters and bag filters are used to remove fine particulates. After effective disinfection, the water is directed into Tofoe’s electrodialysis system.

Step 4: Electrodialysis (ED) System

Electrodialysis utilizes semi-permeable ion-exchange membranes and direct current to remove ions from water. The concentration difference across the membranes drives natural dialysis, while the electric field accelerates ion migration. These membranes—cation-exchange and anion-exchange types—are polymer-based and selectively permeable to ions, serving as the core components of the ED process for high-salinity water treatment.

Step 5: Water Reuse

After treatment in Tofoe’s electrodialysis system, the high-salinity wastewater meets the quality standards for reuse. The system allows adjustable desalination rates ranging from 30% to 99%, depending on requirements. The overall water recovery rate is high, typically reaching 65%–90%. Treated water is collected in a reuse tank and pumped to points of use, while the concentrated stream is returned to the integrated wastewater collection tank for further treatment.

Step 1: Equalization Tank

High-COD wastewater is discharged from the production workshop into an equalization tank. This step helps regulate water quality and flow rate, ensuring stable treatment performance and reducing shock loads on downstream processes.

Step 2: Filtration System

The wastewater then enters a filtration system where quartz sand is used as the filtering medium. Under certain pressure, the water passes through a layer of granular quartz sand to remove suspended solids (SS). After filtration, the water flows into the pH adjustment tank.

Step 3: pH Adjustment Tank

The filtered wastewater enters the pH adjustment tank, which is equipped with an online pH controller, mixers, and automatic dosing systems for sulfuric acid and ferrous sulfate. The pH is maintained between 3–4 to optimize subsequent treatment.

Heavy metal wastewater is a challenging category of hazardous waste that concerns many industries. At Tofoe, we specialize in effective treatment solutions. Here’s a simplified look at our typical process:

Step 1: Equalization Tank

Wastewater from the physical-chemical workshop flows into the equalization tank. This step stabilizes water quality to ensure consistent treatment performance and reduces hydraulic or chemical shock to downstream processes.

Step 2: pH Adjustment Tank

The wastewater then enters the pH adjustment tank, which is equipped with an online pH monitor, mixers, and automatic dosing systems for sulfuric acid and ferrous sulfate to accurately control pH levels.

Step 3: Coagulation and Flocculation System

Next, the wastewater enters the flocculation tank where PAM (polyacrylamide) is added to form flocs. These are then separated in a dissolved air flotation (DAF) unit. Microbubbles generated by released dissolved air help remove suspended solids and bound heavy metals.

Step 4: Evaporation System

The core of the treatment process is the evaporation system. After heavy metal ions are removed, the treated water is directed to a single-effect evaporator. The condensate is discharged to the integrated equalization tank of the wastewater station for further management.

1. Limited Automation in Wastewater Treatment Equipment

Enhancing automated control and monitoring in wastewater treatment helps maintain stable operating parameters and ensures compliance with discharge standards. It also reduces labor costs, minimizes human error, and prevents operational accidents. However, due to budget constraints and limited facility scale, many plants still operate with low automation, which significantly hinders the effective treatment of electroplating wastewater.

2. High Alkali Consumption

Many environmental service companies rely heavily on chemical precipitation methods, often using excessive amounts of alkali. This alkali is used both for acid neutralization and heavy metal precipitation. The main reasons for overdosing include:

Failure to pretreat highly acidic waste streams before introducing them into the wastewater system, which raises treatment costs.

Direct alkali precipitation without recovering and recycling heavy metals, leading to increased alkali usage and higher sludge production.

Lack of automated dosing systems resulting in inaccurate chemical feed—either too much or too little. To meet effluent requirements, companies often overuse chemicals, which not wastes resources but also complicates treatment.

3. Failure to Recover Heavy Metals

Electroplating wastewater often contains high concentrations of heavy metal ions such as nickel and gold. Direct precipitation without metal recovery represents a significant economic loss and increases the heavy metal load in sludge. Additionally, electroplating sludge is classified as hazardous waste, and its treatment remains challenging. In many cases, heavy metal ions are not effectively recovered during the process.

What are the common challenges in achieving Zero Liquid Discharge?

Currently, the widely used ZLD treatment methods include physicochemical processes, biological treatments, and chemical approaches. Major techniques involve evaporative concentration, membrane desalination, electrolysis, and halotolerant microbial treatment.

Each method has its advantages and limitations. For example, evaporation offers high processing capacity and low influent quality requirements. Membrane filtration is simple in principle but is only suitable for low-volume, high-salinity wastewater due to issues like high equipment costs, membrane fouling, and scaling. Electrolysis is more applicable to low-salinity wastewater.

Among existing ZLD technologies, evaporative concentration is relatively effective for high-salinity streams. However, it requires significant thermal energy, leading to the following common concerns:

1.Membrane Fouling

Membrane fouling commonly occurs during reuse stages, where organic contaminants in the feed water accumulate on membrane surfaces. This remains a major issue in ZLD applications.

Recommended solutions include:

Implementing advanced oxidation processes (AOPs)

Using activated carbon adsorption

Selecting fouling-resistant reverse osmosis (RO) membranes

2.Scaling and Corrosion

Evaporation often leads to scaling, which can cause corrosion. High-salinity brine tends to form scale and is often highly acidic or alkaline, with elevated temperatures and chloride levels that corrode metal equipment and piping.

To address this, the following measures can be adopted:

Dosing with acids, alkalis, seed crystals, or antiscalants

Optimizing reaction conditions to inhibit scale formation

3.High Investment and Operational Costs

ZLD systems involve considerable operating expenses, especially when treating large volumes of wastewater. Reducing operational costs is a urgent priority.

A common strategy is to use integrated treatment processes that first reduce wastewater volume through preliminary treatment before undergoing evaporation and concentration.

In the biochemical treatment process of industrial wastewater treatment engineering, microorganisms in activated sludge continuously consume organic matter in the wastewater. In the consumed organic matter, a portion of the organic matter is oxidized to provide the energy required for microbial life activities, while another portion is utilized by microorganisms to synthesize new cytoplasm, thereby promoting microbial reproduction. While microorganisms metabolize, some old microorganisms die, resulting in the production of excess sludge.

Industrial wastewater treatment methods can be divided into four categories based on their principles of action, namely physical treatment, chemical treatment, physicochemical treatment, and biological treatment. The selection of process plan should be based on the actual water quality, including effluent quality (COD, SS, BOD, etc.).

What is industrial wastewater?

Industrial wastewater refers to water generated during industrial production that contains industrial materials, intermediates, finished products, as well as pollutants lost with water during the process. With rapid industrial development, the types and volumes of industrial wastewater have increased significantly, leading to widespread water pollution and serious risks to human health and safety.

What are the levels of industrial wastewater treatment?

Industrial wastewater treatment can be divided into three levels: primary, secondary, and tertiary.

Primary Treatment: This mainly involves physical methods such as screening and sedimentation to remove suspended and floating solids. It prepares wastewater for secondary treatment. Primary treatment typically removes about 30% of BOD (Biochemical Oxygen Demand).

Secondary Treatment: This uses biological processes to break down colloidal and dissolved organic pollutants. After secondary treatment, BOD removal can exceed 90%, allowing the water to meet discharge standards.

Tertiary Treatment: Following primary and secondary steps, this stage further treats hard-to-degrade organics, phosphorus, nitrogen, and other nutrients. Methods include coagulation, filtration, ion exchange, reverse osmosis, ultrafiltration, and disinfection.

What are the common challenges in industrial wastewater treatment?

1.Ineffective Wastewater Segregation

As pollutants in industrial wastewater become more numerous and complex, treatment becomes increasingly difficult. Currently, wastewater is often categorized as general wastewater, chromium-containing wastewater, fluoride-containing wastewater, etc. However, this classification method is often inefficient and impractical.

2.High Costs and Low Recycling Rates

Due to technical limitations, many companies face high costs in treating industrial wastewater. To meet environmental standards, significant human, material, and financial resources are invested. However, non-targeted treatment technologies often result in low efficiency and chemical waste. Although wastewater treatment offers some economic benefits, the returns are generally much lower than the investment, reducing companies’ motivation to treat wastewater effectively.

3.Excessive Alkali Usage

When chemical precipitation is used to treat industrial wastewater, alkali is often overdosed to neutralize acids and precipitate heavy metals—especially when recovery processes are skipped. Additionally, many treatment systems still rely on manual operation, leading to imprecise chemical dosing and further alkali waste.