Coagulant-based emergency water treatment

Emergency water treatment approaches relying on coagulation vary from centralised modular and portable ‘‘kits’’ to ‘‘pointof-use’’ or ‘‘household’’ interventions. Typical coagulation practice in emergencies is reviewed in view of field constraints (e.g. equipment and resources) and contrasted with underlying theory and conventional water treatment procedures. Examples of coagulation in emergencies are also presented based on documented field experiences alongside the discussion of other relevant issues such as process control, sludge production and management, ease of use, and aluminium coagulant residuals in finished waters.

Coagulation with aluminium sulfate has been and is likely to continue to be a key process in successful emergency water treatment and supply operations. This is due to its many advantages that include: wide local availability of aluminium sulfate; relative ease of transport, adaptability to local conditions (i.e. used with local materials and resources), and ease of assimilation by (unskilled) operators with training.