Sand Filter Carbon Filter Belt Softening Fully Automatic Reverse Osmosis Fine Filtration Water Treatment System

Core Process Design Logic & Purification Value

1. Sand filtration (primary physical purification): Remove large particle suspended solids, sediment, rust and colloids in raw water, reduce turbidity to ≤1NTU, avoid physical scratching and blockage of subsequent filter elements and membranes.
2. Carbon filtration (adsorption & dechlorination): Adsorb residual chlorine, color, odor, small molecular organic matter and heavy metal ions in raw water, eliminate the oxidation damage of residual chlorine to the RO membrane (polyamide RO membrane is extremely sensitive to free chlorine), and improve the taste and purity of water.
3. Ion exchange softening (scaling factor elimination): Remove calcium (Ca²⁺), magnesium (Mg²⁺) and other hardness ions in raw water, reduce water hardness to ≤0.03mmol/L, fundamentally avoid calcium carbonate/magnesium carbonate scaling on the RO membrane surface, which is the key protection link for high-hardness raw water.
4. Fully automatic RO (core desalination & deep purification): Intercept ≥97% of dissolved salts, heavy metals, nitrate, bacteria, viruses and trace organic matters in water, realize deep desalination and purification, and produce standard pure water.
5. Terminal fine filtration (water quality polishing): Perform precision filtration on RO produced water to remove tiny microbial flocs, membrane fragments and fine particles generated during RO operation, ensure the cleanliness of the final effluent, and avoid secondary pollution in the water storage and delivery process.

Whole Process Working Principle (Fully Automatic Operation)

1. Raw Water Intake & Boosting: Raw water is pumped into the system by a raw water booster pump with stable pressure (0.2~0.3MPa), and the flow is adjusted according to the rated water production capacity of the system, with dry running and overload protection functions.
2. Sand Filtration Stage: Raw water enters the automatic backwash sand filter (quartz sand as filter material), and under the action of gravity and filtration, large particle impurities (≥5μm) are intercepted on the filter material surface. When the filter pressure difference exceeds the set value (0.05~0.1MPa), the PLC automatically triggers backwashing (water/air combined backwash) to discharge impurities, and resumes filtration after backwashing is completed. Effluent turbidity ≤1NTU.
3. Carbon Filtration Stage: Sand filter effluent enters the automatic backwash activated carbon filter (granular activated carbon/GAC as filter material), and the porous structure of activated carbon adsorbs residual chlorine (≤0.05mg/L after treatment), color, odor, TOC and heavy metal ions (e.g., lead, mercury). The PLC automatically backflushes the carbon filter when the pressure difference is too high, avoiding carbon filter blockage and adsorption saturation.
4. Ion Exchange Softening Stage: Carbon filter effluent enters the automatic regeneration softener (cation exchange resin as the core), and the resin exchanges Na⁺ with Ca²⁺/Mg²⁺ in water to remove hardness ions (water hardness ≤0.03mmol/L after treatment). When the resin is saturated (water hardness exceeds the set value), the PLC automatically triggers the regeneration process (salt absorption → rinsing → displacement) with industrial salt (NaCl) as the regenerant, and the resin resumes softening function after regeneration.
5. Precision Filtration (RO Pre-protection): Softened water enters the 5μm cartridge precision filter to remove fine suspended solids and resin fragments generated during softener regeneration, ensuring the SDI value of RO inlet water ≤5 (the critical index for RO membrane operation), and avoiding physical pollution of the RO membrane.
6. Fully Automatic RO Desalination Stage: Pretreated qualified water is pressurized to 1.0~3.0MPa by a high-pressure RO pump (pressure adjusted according to raw water salinity) and enters the RO membrane module. Water molecules pass through the RO membrane (pore size 0.0001μm) to form pure water, while dissolved salts, bacteria, viruses and other impurities are intercepted and discharged as concentrated water. The system is equipped with automatic scale inhibitor dosing device (auxiliary anti-scaling) and automatic RO membrane flushing device (flushing for 1~2 minutes when starting/shutting down), and the PLC realizes automatic start/stop of the RO system by linking with the pure water tank liquid level. Desalination rate ≥97%, effluent conductivity ≤10μS/cm (for medium-low salinity raw water).
7. Terminal Fine Filtration Stage: RO pure water enters the 0.22μm microporous membrane fine filter (terminal polishing), which removes tiny microbial flocs, membrane fragments and fine particles in the pure water, ensuring the effluent particle size ≤0.22μm, and the pure water quality is more stable and clean.
8. Pure Water Storage & Delivery: Terminally filtered pure water is stored in a sealed food-grade pure water tank, and a pure water delivery pump with pressure maintaining function delivers the pure water to the water use point with stable pressure (0.2~0.3MPa). The tank is equipped with a liquid level sensor to realize interlock control with the front-end system (stop water production when full, start automatically when low).

Main Component System (Modular Fully Automatic Integrated Design)

1. Raw Water Intake & Boosting Unit

• Raw water booster pump: Stainless steel centrifugal pump, flow matching system rated water production (1~50m³/h customizable), head 20~30m, with dry running, overload and overpressure protection;
• Raw water flow meter/pressure gauge: Real-time monitoring of intake flow and pressure, data displayed on the touch screen;
• Water inlet solenoid valve: Linked with PLC, automatic on/off, and interlocked with the pure water tank liquid level.

2. Sand Filtration Unit (Automatic Backwash)

• Quartz sand filter tank: FRP/stainless steel pressure tank, volume matching system flow, filter material is graded quartz sand (0.5~1.2mm);
• Automatic backwash valve group: Electric butterfly valve/ball valve, realize automatic switching of filtration/backwash/rinse working conditions;
• Air blower (optional): For water/air combined backwash, improve backwash efficiency (suitable for high-turbidity raw water);
• Differential pressure transmitter: Monitor filter inlet/outlet pressure difference, trigger automatic backwash when exceeding the set value.

3. Carbon Filtration Unit (Automatic Backwash)

• Activated carbon filter tank: FRP/stainless steel pressure tank, same volume as sand filter tank, filter material is granular activated carbon (8~30 mesh, coconut shell carbon is preferred for high adsorption capacity);
• Same automatic backwash valve group/differential pressure transmitter as sand filter unit;
• Residual chlorine detector: Real-time monitoring of carbon filter effluent residual chlorine, automatic alarm when exceeding the set value (≥0.1mg/L).

4. Ion Exchange Softening Unit (Automatic Regeneration)

• Softener tank: FRP/stainless steel pressure tank, filter material is strong acid cation exchange resin (001×7 type);
• Automatic regeneration valve group: Multi-way diaphragm valve, realize automatic switching of softening/salt absorption/rinsing/displacement working conditions;
• Salt tank: PE material, store industrial refined salt (NaCl ≥99%), with liquid level sensor (alarm when salt is low);
• Hardness tester: Real-time monitoring of softener effluent hardness, trigger automatic regeneration when exceeding the set value.

5. RO Pre-protection Precision Filtration Unit

• 5μm cartridge filter: Stainless steel shell, with 2~6 filter elements (matching system flow), replaceable PP melt-blown filter elements;
• Filter element replacement reminder: Pressure difference transmitter triggers alarm when filter is blocked, reminding manual replacement of filter elements.

6. Core Purification – Fully Automatic RO Desalination Unit

• High-pressure RO pump: Stainless steel horizontal multistage centrifugal pump, flow 1.2 times the system rated water production, pressure 1.0~3.0MPa adjustable;
• RO membrane module: Low-pressure composite RO membrane (8040/4040 model), 2~20 elements (matching system flow), desalination rate ≥97%, polyamide material;
• RO membrane shell: FRP/stainless steel, pressure-bearing ≥4.0MPa, single/multiple shell series-parallel connection;
• Automatic dosing system: Scale inhibitor dosing pump + medicament tank, automatic dosing according to raw water flow (food-grade/industrial scale inhibitor);
• RO flushing valve group: Automatic flushing of RO membrane when starting/shutting down, remove membrane surface pollutants;
• Concentrated water regulating valve: Adjust RO system water recovery rate (60~75% for medium-scale systems), optional energy recovery device (ERD) for energy saving (suitable for high-salinity raw water).

7. Terminal Fine Filtration & Pure Water Storage Unit

• 0.22μm terminal fine filter: Stainless steel shell, microporous membrane filter element (PP/PTFE material), terminal water quality polishing;
• Sealed pure water tank: 304 stainless steel food-grade tank, volume 5~50m³ (customizable), with air filter (0.22μm), liquid level sensor and overflow port (anti-secondary pollution);
• Pure water delivery pump: Stainless steel centrifugal pump, with pressure maintaining valve, stable water supply pressure for water use points;
• Water quality monitoring instrument: Conductivity/TDS meter, pH meter, turbidity meter (installed at pure water tank outlet), real-time data display and data recording.

8. Integrated PLC Control & Monitoring Unit (Core of Full Automation)

• PLC control cabinet: With 7/10-inch touch screen operation interface, support Chinese/English, real-time display of all operating parameters (flow, pressure, turbidity, conductivity, hardness, residual chlorine, liquid level);
• Sensors & transmitters: Differential pressure, pressure, flow, turbidity, residual chlorine, hardness, conductivity, liquid level sensors, all data transmitted to PLC;
• Automatic valve group: Electric solenoid valve, electric ball valve, pneumatic valve, realize automatic switching of all working conditions;
• Acousto-optic alarm device: Audible and visual alarm for abnormal conditions (low raw water pressure, unqualified pretreatment effluent, high RO pressure, unqualified pure water quality, low liquid level/salt level), and automatic shutdown protection for serious faults;
• Data management & remote monitoring: Support real-time data recording, U disk export and historical data query; optional 4G/WiFi module, realize remote monitoring/operation/alarm via mobile phone/computer (cloud platform);
• Power distribution system: With overvoltage, overcurrent, leakage and phase loss protection, ensure the safe operation of the whole system.

Core Product Features

1. Multi-stage progressive purification, super high water quality stability

   The sand + carbon + softening + RO + fine filtration process covers all types of raw water impurities (physical, chemical, biological), and the produced water quality is super stable: conductivity ≤10μS/cm, turbidity ≤0.1NTU, residual chlorine 0mg/L, hardness ≤0.03mmol/L, bacteria ≤0CFU/mL, which can meet the national standards of industrial pure water (GB/T 19249-2018), drinking pure water (GB 17323-1998) and pharmaceutical purified water (Chinese Pharmacopoeia).

2. Full automatic unmanned operation, ultra-low labor cost

   The whole system is controlled by PLC, realizing automatic backwashing of sand/carbon filter, automatic regeneration of softener, automatic start/stop of RO system, automatic flushing of membrane, automatic alarm/protection; no on-site manual duty is required, only regular inspection and consumables replacement are needed, which greatly saves labor costs (suitable for unattended water supply scenarios).

3. All-round RO membrane protection, ultra-long service life

   The multi-stage pretreatment fundamentally eliminates the three major risks of RO membrane: physical pollution (sand/carbon filtration + precision filtration), oxidation damage (carbon filtration dechlorination), scaling (ion exchange softening + scale inhibitor dosing); the RO membrane is also equipped with automatic flushing, and its service life is extended to 3~5 years (1~2 years longer than the traditional non-softened system).

4. Strong raw water adaptability, wide application scenarios

   Specially designed for harsh raw water quality: applicable to groundwater with high turbidity/high hardness/high salinity, tap water with unstable residual chlorine/turbidity, surface water (river/lake water) with complex impurities, and reclaimed water after primary treatment; the system can adapt to different raw water quality by simple parameter adjustment (backwash frequency, regeneration cycle, RO pressure).

5. Modular integrated design, easy installation & maintenance

   Skid-mounted/containerized modular assembly, all components on a stainless steel frame, standardized pipelines and quick-connect joints; on-site installation only needs to connect raw water pipe, pure water pipe and power supply, which can be put into use in 1~3 days; modular design makes consumables replacement (filter element, resin, membrane) and component maintenance simple and fast.

6. Complete protection functions, high equipment safety factor

   The system is equipped with multiple layers of protection: raw water pump dry running protection, high-pressure pump overload/overpressure protection, pretreatment effluent unqualified interception protection, RO membrane high/low pressure protection, pure water tank overfill/empty protection, power failure memory protection; it can automatically alarm and shut down for faults, avoiding equipment damage caused by misoperation or abnormal raw water quality.

7. High water recovery rate, energy saving and environmental protection

   The RO system is equipped with a concentrated water regulating valve and optional energy recovery device (ERD), the water recovery rate is up to 60~75% (higher than the traditional single-stage pretreatment system of 50~60%); the automatic backwash/regeneration of pretreatment units adopts quantitative water/salt control, reducing water and chemical consumption, and being more energy-saving and environmentally friendly.

8. Flexible configuration, customizable according to demand

   The system flow (1~50m³/h), tank material (FRP/stainless steel), control function (local/remote) and post-treatment can be fully customized according to actual raw water quality, water use demand and on-site conditions; it can be expanded to ultra-pure water system (RO+EDI) for high-standard water demand.

Typical Application Scenarios

1. Industrial process water: Electronics, semiconductors, electroplating, chemical industry, power plants, cosmetics, plastic molding and other industries, used as process water, cleaning water, cooling water and boiler feed water (low hardness meets boiler anti-scaling requirements);
2. Pharmaceutical & food industry: Pharmaceutical purified water for pharmaceutical preparation, injection water raw water, food and beverage production water (e.g., beverage, dairy products, beer), meeting GMP and food safety national standards;
3. Commercial centralized water supply: Large hotels, hospitals, schools, office buildings, commercial plazas and bottled water stations, providing high-standard pure water for drinking, catering, cleaning and central air conditioning water;
4. Municipal & rural water supply: Rural centralized drinking water purification (groundwater with high hardness/bitter and salty water), municipal tap water deep purification (improving tap water taste and quality), and small and medium-sized water plant pure water production;
5. High-standard industrial water: Precision manufacturing, new energy (battery production, photovoltaic panel cleaning), laboratory pure water raw water (universities, research institutes, testing institutions), meeting the ultra-high water quality requirements of high-tech industries;
6. Boiler feed water: Industrial boiler, central heating boiler feed water softening and desalination, reducing boiler scaling and improving heat efficiency, extending boiler service life.

Key Technical Parameters (Standard Configuration, 5m³/h Model as an Example)

Daily Operation & Maintenance (Low Cost, Simple Operation)

1. Consumables Replacement (Regular & Timely)

• 5μm precision filter element (RO pre-protection): Replace every 3~6 months (adjust according to raw water turbidity);
• 0.22μm terminal fine filter element: Replace every 6~12 months;
• Quartz sand filter material: Replace every 3~5 years (supplement in time when reduced);
• Activated carbon filter material: Replace every 2~3 years (adsorption capacity attenuation);
• Cation exchange resin: Replace every 3~4 years (resin aging);
• RO membrane: Replace every 3~5 years (desalination rate <90% as the replacement standard).

2. Medicament & Raw Material Supply (Continuous & Sufficient)

• Industrial salt (softener regenerant): Ensure the salt tank is full, use refined industrial salt (NaCl ≥99%) to avoid resin pollution;
• Scale inhibitor (RO anti-scaling): Check the medicament tank level regularly, add food-grade/industrial scale inhibitor in time, and ensure the dosing pump is running normally;
• Cleaning agent (optional): Prepare citric acid (acid cleaning) and sodium hydroxide (alkali cleaning) for periodic chemical cleaning of sand/carbon filter and RO membrane.

3. Regular Inspection of Core Components (Monthly)

• Check the sealing performance of all valves and pipelines to prevent water leakage;
• Check the operation status of all pumps (booster pump, high-pressure pump, delivery pump), add lubricating oil to the bearing part regularly;
• Check the automatic valve group and multi-way valve for flexible switching, and clean the valve core filter screen if blocked;
• Clean the dust of the PLC control cabinet and ensure good heat dissipation (avoid short circuit caused by dust accumulation).

4. Periodic Calibration of Instruments (Annual)

• Calibrate turbidity meter, residual chlorine meter, hardness meter, conductivity/TDS meter, pH meter;
• Calibrate all pressure gauges, flow meters and differential pressure transmitters;
• Calibrate the liquid level sensor of the pure water tank and salt tank to ensure accurate interlock control.

5. Periodic Chemical Cleaning (6~12 Months)

• For raw water with high turbidity/salinity, perform chemical acid/alkali cleaning on sand/carbon filter and RO membrane every 6~12 months to restore filtration/adsorption/desalination capacity;
• Clean and disinfect the pure water tank every 6~12 months with food-grade disinfectant (chlorine dioxide/ozone) to prevent secondary pollution.

Customization Options

1. Raw water quality customization: Add a coagulant dosing device for high-turbidity raw water; add a degasser for raw water with high CO₂/H₂S; add a security filter for raw water with high suspended solids;
2. Water quality demand customization: Add EDI ultra-pure water module for ultra-pure water demand (conductivity ≤0.1μS/cm, electronic/laboratory); add UV/ozone sterilizer for drinking water demand; add mineralization device for mineral water production; add TOC remover for pharmaceutical water demand;
3. On-site condition customization: Customize skid-mounted size for narrow installation space; add rainproof/sunshade/anti-freezing/corrosion-resistant design for outdoor/coastal installation; adopt containerized design for mobile water supply;
4. Function customization: Add 4G/WiFi remote monitoring and cloud data storage; add automatic chemical cleaning system for unattended scenarios; add water metering and charging system for commercial water supply; add energy recovery device (ERD) for high-salinity raw water to save energy;
5. Material customization: Upgrade all tanks/pipelines to 316L stainless steel for corrosive raw water (e.g., coastal groundwater, chemical wastewater); use food-grade coconut shell activated carbon for food/pharmaceutical water demand.