Drinking Water: Fundamentals and Operation

Define potable water as meeting sanitary, aesthetic, and microbiological standards. Explain that surface and groundwater sources are tested under legislation and limits, disinfected, and delivered to homes.

Explore how conventional drinking water treatment uses coagulation, flocculation, sedimentation, filtration, and disinfection to remove suspended solids from surface water and groundwater.

Explain how coarse, medium, and fine screens remove debris at the catchment intake and how grit chambers sediment sands and discrete particles before potable water treatment.

Explore tray aeration and chemical oxidation to remove iron and manganese from water. Learn how oxidants, pH adjustments, and subsequent coagulation, flocculation, and filtration produce safe, clear water.

Coagulation and flocculation add coagulants and flocculants to neutralize colloidal charges, form large flocs, and remove suspended and colloidal solids by sedimentation in drinking water treatment.

Learn how coagulation neutralizes negative colloidal charges with aluminum, iron, and calcium coagulants. Understand alkalinity, pH effects, and how polymeric coagulants like pac improve floc formation and reduce sludge.

Examine rapid mixing in drinking water treatment, comparing hydraulic and mechanical mixers as they generate turbulence, enable uniform coagulant dispersion, and meet retention time and flow considerations.

Learn how flocculation accelerates agglutination to form dense, settleable flocs via polymers, activated silica, and clays; use jar tests to optimize dosage and reduce coagulant demand.

Explore slow mixing in drinking water coagulation and flocculation, compare hydraulic and mechanical flocculants, horizontal and vertical flow designs, and the role of gradual mixing for larger flocs.

Learn how coagulation and flocculation remove suspended solids, COD, and BOD, while dissolved organic matter and nitrates remain, and how pH, turbidity, salts, temperature, and mixing govern jar-test dosages.

Learn the jar test procedure to optimize coagulant and flocculant dosages for drinking water treatment, measuring pH, turbidity, alkalinity, cod, and removal efficiency with ferric chloride, aluminum sulfate, and polymers.

Extrapolate jar test results to the plant flow and develop dosing strategies using control curves to set coagulant and polymer doses for rural water treatment.

Learn sedimentation theory for drinking water: coagulation and flocculation form flocs that settle in a horizontal flow settler, with four sedimentation types and routine sludge purge.

Optimize settler performance by distributing inflow to avoid dead zones and thermal stratification, using a diffuser wall or flow baffle to achieve homogeneous piston flow and effective sludge collection.

Examine circular upflow and lamella plate settlers, with center-feed inlets, bottom scrapers, purge removal, weirs, and regular cleaning practices.

Explore slow sand filtration in drinking water treatment, detailing the biological layer's role, filtration mechanisms, cleaning methods, sand replacement options, and the need for post-treatment chlorination.

The rapid filter removes coagulated water by downward flow through a sand bed over gravel, collected by nozzles. Backwashing reverses flow to clean the bed, taking 5–10 minutes.

Explore filter maturation after backwashing, turbidity changes, and how filter media such as silica sand, anthracite, garnet or ilmenite affect uniformity and filtration rates up to 16-18 m per hour.

Explore filtration fundamentals and pressure filters, distinguishing slow and fast sand filters by sand size and filtration velocity. Understand backwash procedures and air-assisted washing for efficiency.

Apply chlorine disinfection after filtration to remove pathogens from treated water, considering turbidity, temperature, pH, and a minimum 30-minute contact time that favors hypochlorous acid.

Explain the chlorine break point, how ammonia forms chloramines and free residual chlorine, and how pH and chlorine-to-ammonia ratio shape monochloramine, dichloramine, and trichloramine.

Learn disinfection methods for new drinking water systems, including chlorine methods with and without ammonia, trihalomethanes formation risks, and alternatives like chlorine dioxide and activated carbon filtration.

Learn how sludge from drinking water treatment is thickened, de-watered, and dried using gravity thickeners, drying beds, and filters with polymers for compliant disposal.