Coagulation and Flocculation in Water Treatment Systems
Summary
Coagulation and flocculation constitute core processes in both drinking water and wastewater treatment, aimed at removing suspended solids, colloidal particles and associated contaminants. In coagulation, chemical agents destabilise charged colloids by neutralising surface charges or by enmeshing particles in precipitating metal hydroxides. Subsequent flocculation promotes the gentle aggregation of destabilised particles into larger, settleable flocs through slow mixing, bridging between polymer chains and sweep mechanisms. Key operational parameters include the type and dose of coagulant or flocculant, pH, mixing intensity and residence time. Conventional inorganic coagulants such as aluminium sulphate, iron salts and pre-hydrolysed polyaluminium chlorides remain widely used, offering rapid turbidity and colour removal but often generating non-biodegradable sludge and residual metal concentrations. Recent efforts focus on biodegradable polymers, biocoagulants and hybrid materials to reduce chemical footprint, improve sludge valorisation and extend treatment to emerging contaminants such as pharmaceuticals, heavy metals and pathogens. Advances in monitoring and control, including online turbidity and zeta-potential sensing, enable real-time optimisation of coagulation-flocculation trains. Novel process configurations, such as inline coagulation with membrane filtration or enhanced sludge dewatering, are driving integrated water reuse schemes and decentralised treatment in resource-limited settings. These developments underscore the global importance of coagulation and flocculation for public health, environmental protection and circular water management.
Research from Nature Portfolio
No recent Nature Portfolio content available.
Coagulation and Flocculation in Water Treatment Systems publication trend
The graph below shows the total number of articles in coagulation and flocculation in water treatment systems across all publications each year (not limited to Nature Index journals).
Technical terms
Coagulation: Destabilisation of colloidal particles by neutralising surface charges or by enmeshment within precipitated metal hydroxides.
Flocculation: Controlled aggregation of destabilised particles into larger flocs through gentle mixing, polymer bridging or sweep floc mechanisms.
Floc: A loose assembly of aggregated particles formed during flocculation, which can be removed by sedimentation or filtration.
Charge neutralisation: Reduction of repulsive forces between particles by balancing surface charges, facilitating initial particle destabilisation.
Polymeric bridging: Linking of destabilised particles by long-chain polymers that adsorb onto multiple surfaces, promoting floc growth.
Turbidity: A measure of water clarity caused by suspended solids; a primary indicator of treatment performance.
References
- Ecosystem-inspired model and artificial intelligence predicts pollutant consumption capacity by coagulation in drinking water treatment. Environmental Chemistry Letters (2023).
- Vanadium removal and floc characteristics of tannin biocoagulants and iron sulphate in the treatment of mine effluent. Chemical Engineering Journal (2023).
- Application of Natural Coagulants in Water Treatment: A Sustainable Alternative to Chemicals. Water (2022).
About these summaries
This Nature Research Intelligence Topic summary is created with the cited references and a large language model. We take care to ground generated text with facts, and have systems in place to gain human feedback on the overall quality of the process in line with our AI principles. We strive to create accurate and useful summaries for people unfamiliar with the research topic and that supports this goal. These pages are a beta release and will be updated as we learn how best to help people gain value from a research topic summary.
Turn complex research questions into confident strategic decisions
When you're under pressure to set direction, justify investment, or understand your competitive position, you need more than raw data — you need trusted insights you can act on.
Benchmark your performance against global peers using robust, methodologically sound analysis.
Combine quantitative metrics with qualitative expert insight to uncover strengths, gaps and emerging opportunities.
Gain tailored, decision-ready recommendations aligned to your strategic priorities.
Talk to us to learn more about our data dashboards and bespoke strategy reports.
Grow research skills, confidence and careers with training built for every stage of the research lifecycle.
Developed with Nature Portfolio journal Editors and internationally renowned experts. Discover three ways to learn:
Self-paced, online courses in convenient bite-sized units, covering key skills across scientific writing, publishing, grant writing, data analysis, and more.
Expert trainer-led workshops with hands-on exercises and real-time feedback across core research skills, delivered via interactive group sessions.
Editor-led workshops combining core principles in writing and publishing, personalised 1:1 feedback from Nature Portfolio Editors and hands-on exercises.
Explore course catalogues and workshop agendas, enquire about the options or request institutional pricing.