M.Sc. Urszula Gabriel Institute of Chemical Engineering and Environmental Protection Processes WATER NETWORKS OPTIMISATION TO MINIMISE WATER USE AND WASTEWATER GENERATION

Plan of presentation 1. Introduction 2. Evolution of water network structures 3. Principles of water minimisation 4. Review of design procedures for water networks 5. Scheme of elaborated algorithm 6. Example of algorithm application 7. Conclusions

Introduction Benefits of water network optimisation: lower costs of fresh water intake and wastewater disposal lower environmental hazard solving problems of fresh water shortage One of the main strategies: maximizing the reuse of water within the plant and seeking opportunities to use the outlet water from one operation to satisfy the water requirement of another or the same operation

Evolution of water network structures

Principles of water minimisation Contamination present in the water doesn’t have to be totally removed but should be reduced to the level enabling reuse of the stream water streams of different contamination level, which are supposed to be reused, shouldn’t be merged before sending them to treatment unit water slightly contaminated should be directly reused and the most contaminated water streams should be regenerated

Review of main procedures

Scheme of algorithm

Water streams allocation algorithm The developed method is based on „nearest neighbour algorithm”: to satisfy a particular water demand, the source streams to be chosen are the nearest available neighbours to the demand in terms of contaminant concentration. If the solution given above requires mixing with fresh water, the most contaminated stream is chosen for regeneration to replace the raw water.

start n s, n d arrC s (n s, 3) arrC d (n d, 3) indC s = n s indC d = n d CSCDCSCD Y indC s =indC s-1 N Y C s = C n FSFDFSFD stop Y indC s = indC s-1 indC d = n d N F S <>0 YN N mix./ regen. results_tab

Expert system The expert system enables selection of the optimal scheme for the treatment of contaminated water according to its characteristic (type of contaminant), required purification level and efficiency of treatment option.

Treatment schemes Sedimentation -> D Chemical treatment (Al) – sand filter -> C Chemical treatment (Al) – trickling filter – activated carbon – ultrafiltration -> B Chemical treatment (Al) – trickling filter – activated carbon – ultrafiltration – RO -> A A, B, C, D – water quality

Efficiency matrix of treatment modules MethodeSSBODCH 3 OHHeavy Metals Bacteria Sedimentation Biological treatment chemical treatment Treackling filter Activated carbon UF RO

Example of algorithm application - Problem statement

- Schemes of obtained water networks

- Simulation results

As an optimum treatment method the activated carbon is chosen. methodeSSBODCH 3 OHHeavy Metals Bacteria Sedimentation Biological treatment chemical treatment Treackling filter Activated carbon UF RO

Conclusions Applied algorithm: -Indicates water structure for water streams allocation (giving 45% lower freshwater intake in above case) and for decentralised water regeneration (giving 75% lower freshwater intake) -proposes an efficient water treatment method.