Water Treatment Plant Design: Complete Guide with Excel Tool

Screening acts as a pre-treatment in surface water intakes, trapping large debris to protect equipment. Coarse and fine screens, manual and automatic, remove debris before flow enters the treatment process.

Design a manual inclined coarse screen for water treatment by calculating opening area from flow and velocity, then determine width, length, bar spacing, and freeboard.

Design a coarse bar screen for a wwtp, with 38 openings at 25 mm and 37 bars at 10 mm, yielding a 1.3 m rack and 2.2 m long.

Learn how coagulation and flocculation reduce turbidity in surface water by neutralizing colloidal particles and forming flocs. Apply jar tests, coagulant feeding, mixing, and sedimentation design for effective treatment.

Identify types of coagulants, including alum and iron coagulants, and poly aluminum chloride, along with coagulant aids, and analyze factors like alkalinity, pH, temperature, turbidity, and mixing that influence coagulation.

Jar test to simulate coagulation, flocculation, and sedimentation, identifying the best coagulant and optimal dosages under varying pH, alkalinity, and mixer conditions for water treatment design.

Explore coagulant feeding techniques—dry powder versus wet solution—design coagulation tanks with rapid mixing and flocculation, and evaluate pros and cons, including an alum solution tank for 20,000 m3/d.

Explore flash mixing design for coagulation in water treatment, detailing inline mechanical, inline static, and hydraulic mixing methods, and deriving mixing power from velocity gradient and detention time.

Explore a practical design example for a rapid mix (coagulation) tank at 20,000 m3/d, calculating tank volume, dimensions, and mixer power using temperature-based viscosity, jar test g, and Excel spreadsheet.

Design a square rapid mixing coagulation basin to treat 7570 m3/d, compute volume and dimensions, determine mixer power and impeller size, and apply baffle configurations.

Explore coagulation design using an Excel tool to model a square rapid mixing basin, calculate volume from flow and detention time, and validate with D/W and Reynolds checks.

Explore the flocculation step after coagulation, using jar tests to select coagulant concentration C, detention time T, and G; design three-stage basins with gentle mixing to form quickly settling flocs.

Explore the types of mixing in the flocculation process, including paddle wheels, baffled chambers, and horizontal and vertical configurations. Highlight the advantages of paddle wheels over baffled chambers.

Design flocculation basins with three compartments and three mixers, determine three optimum g values and total detention time (20–60 minutes) via jar tests and Excel-based design guidelines.

Learn design equations for sizing flocculation tanks, emphasizing redundant reactors and parallel flows, determining volume, dimensions, motor power, and tip speeds from jar tests and regulations.

Explains a solved design of a cross-flow paddle wheel flocculation basin for 50,000 m3/d, computing GT, dimensions, paddle arrangement, and motor power with area checks.

Use this Excel tool to design a water treatment plant's flocculation stage, entering blue box values to automatically calculate basin volumes, compartment layouts, paddle wheel dimensions, and optimized, economical configurations.

Learn how rectangular sedimentation tanks use inlet structures, baffled distribution, and horizontal laminar flow to achieve gravity settling, sludge removal by scrapers, and effluent collection for treatment.

Design an inlet structure with a baffled wall and perforations to evenly distribute flow into the settling zone. Minimize disturbance, short-circuiting, and dead zones.

Design the sludge zone of a rectangular sedimentation tank with a mechanical scraper and inlet hopper, and size the hopper from suspended solids and daily sludge volume.

Design a rectangular sedimentation tank by determining settling zone dimensions from inlet to outlet, using diffuser wall, with 4–8 hours retention time and a 25–40 m3/m2/day surface loading rate.

Design the outlet structure of a rectangular sedimentation tank using launders with 90-degree V-notches to ensure steady, minimally turbulent flow to the collection channel and effluent pipe.

Present a practical sedimentation tank design example for a 4000 m3/h water treatment plant, calculating minimum volume, settling area, tank dimensions, weir and launder layout, and daily sludge production.

Learn to design a rectangular sedimentation tank in Excel using blue input cells and formulas to compute flow, volume, area, depth, tank count, and regulatory checks.

Demonstrate circular sedimentation tank design with center feed, radial flow, baffles, and v-notches, directing clarified water to the periphery and sludge to a center hopper for filtration.

Explore the inlet structure of a circular clarifier, comparing central and peripheral fields, with middle effluent, perforated baffles, sedimentation to the hopper and launders.

The sludge zone of a circular clarifier uses a blade-equipped scraper rotating to direct sludge into the hopper, while peripheral driven designs save energy over central driven ones.

Design sedimentation zone of a circular clarifier by calculating diameter and water depth to estimate volume from retention time and flow, and determine number of tanks via surface loading rate.

Design the outlet structure of a circular clarifier using a 90-degree v-notch weir to ensure even overflow, minimize turbulence, and maintain 150–300 m3/(m·d) weir loading with 150–300 mm intervals.

Design example for a 5000 m3/h water plant uses six 30 m clarifiers at 5 m depth (21,207 m3) and checks retention time, surface area, and laminar flow via Excel.

Design a circular clarifier tank with an Excel spreadsheet that inputs flow, retention time, and slr. Use blue input boxes and yellow outputs to compute volume, area, and depth.

Master traditional sand filtration by comparing slow and rapid methods, remove suspended solids to below 0.3 NTU, and apply design calculations with Excel for clear water and disinfection.

Begin with rapid sand filtration after coagulation, flocculation, and clarification to remove suspended solids and polish water, noting its purely physical action and limited pathogen removal.

Study rapid sand filter components and media configurations—mono, dual, and multi-media with sand, anthracite, and garnet, plus drainage, wash troughs, and backwashing systems.

Backwash rapid sand filters by emptying the filter, air scouring, and wash water injection, guided by head loss, turbidity, and time criteria, with a ripening period and valve sequences.

Design rapid sand filters by sizing unit dimensions from the rate of filtration and selecting media layers, troughs, and wash considerations for reliable operation.

design a rapid sand filtration system for 50,000 m3/d, using 12 filters and wash troughs, achieving 2,500 m3/h via a 500 m2 filtration area.

Create an excel spreadsheet to design rapid sand filtration, using blue inputs and yellow outputs to compute daily flow, rate of filtration, surface area, and functional units.

Slow sand filtration uses gravity-driven sand and gravel to remove suspended matter and pathogens with a biological schmutz deck, requiring low turbidity water and minimal pre-treatment.

Explore slow sand filter design—rectangular basins with sand over gravel and shared walls for efficiency, PVC drainage with 2–4 mm perforations, and the schmutzdeck layer's ripening with periodic re-sanding.

Explain pre-treatment with plain sedimentation for turbidity above 50 before slow sand filtration, and post-treatment chlorination to maintain residual chlorine for safe storage and distribution.

Design a slow sand filter using the rate of filtration to size top area and media layers. Apply to a 50,000 m3/day case with five rectangular filters and freeboard.

Design a slow sand filtration in Excel by inputting 50,000 m3/h and 20 hours, calculating flow and filtration rate to derive 2000 m2 area for five units and standby filter.

Explore the disinfection step in water treatment, comparing chlorination, UV, and ozonation, their design considerations and monitoring, targeting bacteria, viruses, and protozoa to ensure safe water.

Chlorination overview highlights chlorine as the most widely used disinfectant, effective against pathogens and easily measured, with residual chlorine after primary and secondary disinfection.

Compare chlorine types for water treatment—gas, calcium hypochlorite powder or tabs, and sodium hypochlorite—and note their concentrations, safety, storage, and on-site electrolysis options.

Understand chlorine dose, chlorine demand, and residual chlorine, start with 2–5 mg/L to reach 0.2–0.5 mg/L after 30 minutes by testing and adjusting accordingly.

Compare methods for monitoring residual chlorine: continuous online analyzers for real-time dosage adjustment; grab sampling with lab analysis for accurate results; and portable colorimetric kits using DPD for quick estimates.

Design chlorine contact tanks using CT value with baffles for 30 minutes, inject chlorine, verify residual chlorine, and size per EPA Giardia lamblia city values considering temperature, pH, turbidity.

Design chlorine contact tanks by determining the ct10 value from the design table, computing t10 from concentration, and using serpentine baffling to maximize residence time and tank volume and dimensions.

Design a chlorine contact tank for 10,000 m³ per day, determine Ct10 and detention time, choose two serpentine baffled tanks, and verify 2 mg/l residual chlorine within safety limits.

Ultraviolet disinfection uses 254 nm light to inactivate bacteria and protozoa in water as a rapid, chemical-free physical process, with pretreatment requirements.

Design and select UV disinfection systems for water treatment, comparing closed vessels with open channel setups, and optimize dose via flow, transmittance, EPA pathogen targets, and monitoring.