Water is known as a scarce resource on Earth and the global warming will lead to intensify this phenomenon. Initiatives are taken around the World to save this resource and to modify the habits that waste it. Sanitation systems in most developed countries use drinkable water to highly dilute the household output and to carry it to treatment plants. However, one-third of the World population does not have access to improved sanitation and 15% is still practicing open defecation because of the lack of sanitation systems. Autonomous sanitation systems can be a solution to both problems by their easy accessibility and by saving water energy. WeCo is a French company that developed and designed for five years autonomous flushes toilets for sustainable cities. The technology is based on a biological treatment through aerobic digestion of the sludges and on a chemical treatment by electrochlorination of the filtered wastewater, that permit to recycle the treated water to the flush and use the same water during several days and months without adding new drinkable water. The digested sludge can then be valorized and excess water from the process might be used for cleaning or for watering public gardens and plants. This study permitted to give theoretical data about the inlet and outlet compounds of the system and to optimize the autonomy of the system and the quality of the treated water. It was obtained that for a frequency of 94 uses per day and if the excess clean water can be regularly emptied, the autonomy of the system can reach 435 days with an initial quantity of water of 1.32m3 before to empty the sludges. A Life Cycle Assessment (LCA) of the complete toilet was also realized for a use in a public market in Grigny, France. The WeCo internal purpose of this LCA was to do a first estimation of the environmental impacts of the system to localize and reduce them. It was also to determine if the system is environmentally competitive with the conventional wastewater treatment plants and with the existing autonomous sanitations as chemical toilets. Results shown that most impacts are coming from the high quantity of stainless-steel used for the container structure and from the energy used, especially during the wastewater treatment. It was also established that WeCo toilets have bigger environmental impacts than chemical toilets, possibly due to its more complex chain of production.
L’acqua è conosciuta come una risorsa scarsa sulla Terra e il riscaldamento climatico intensificherà questo fenomeno. Iniziative sono prese nel mondo per salvare questa risorsa e modificare le abitudini a sprecarla. Nei paesi sviluppati, i sistemi fognari usano l’acqua potabile per dilutare le acque di scarico et trasportale nei impianti di trattamento. Tuttavia, un terzo della popolazione mondiale non ha accesso a risanamenti migliorati e 15% praticano la defecazione aperta dal manco di sistemi fognari. Sistemi sanitari autonomi possono essere una soluzione a questi due problemi dalla loro accessibilità e dalle loro economie in acqua e in energia. WeCo è un azienda francese che sviluppa e disegna da cinque anni bagni autonomi con scarico d’acqua nelle città sostenibili. La technologia è basata su trattamenti biologici da digestione aerobica dei fanghi e chimici da elettroclorurazione dell’acqua di scarico filtrata, consentando a riciclare l’acqua trattata allo scarico per riusarla alcuni mesi senza mai aggiungere di nuovo acqua potabile. I fanghi digeriti possono essere valutati e l’eccesso di acqua puo essere utilizzata per la pulizzia del bago o per irrigare giardini pubblici. Questa studia ha permesso di ottenere dati teorici sui componenti in entrata e in uscita del processo e di ottimizare l’autonomia del sistemo e la qualita dell’acqua trattata. E stato ottenuto che per una frequenza di utilizzo di 94 persone al giorno e considerendo che l’acqua pulita in eccesso puo essere vuotata, l’autonomia del sistema raggiunge 435 giorni con una quantita iniziale di acqua di 1.32m3 prima di svuotare i fanghi. Un analisi del ciclo di vita (ACV) del bagno WeCo è anche stato realizzato per un installazione in 2020 di un bagno in un mercato publico in Grigny, Francia. L’obiettivo interno di WeCo era di avere una prima stima dei impatti ambientali del sistema per localizzarli e ridurli. Il fine era anche di determinare se il sistema è ambientalmente competitivo con gli impianti di depurazione e con gli sanitari autonomi esistanti come i bagni chimici. I resultati hanno mostrato che la maggiore parte degli impatti vengono dalla grande quantita di acciaio inossidabile usata nella struttura del container e dall’energia isata, particolarmente durante la fasa di trattamento dell’acqua. Era anche dedotto che i bagni WeCo hanno impatti più elevati dagli bagni chemici, probabilmente dal loro processo di produzione più complesso.
Analysis and life cycle assessment of a wastewater treatment process by electrochlorination for autonomous flush toilets
THOUVENIN, EDOUARD JACQUES OLIVIER
2019/2020
Abstract
Water is known as a scarce resource on Earth and the global warming will lead to intensify this phenomenon. Initiatives are taken around the World to save this resource and to modify the habits that waste it. Sanitation systems in most developed countries use drinkable water to highly dilute the household output and to carry it to treatment plants. However, one-third of the World population does not have access to improved sanitation and 15% is still practicing open defecation because of the lack of sanitation systems. Autonomous sanitation systems can be a solution to both problems by their easy accessibility and by saving water energy. WeCo is a French company that developed and designed for five years autonomous flushes toilets for sustainable cities. The technology is based on a biological treatment through aerobic digestion of the sludges and on a chemical treatment by electrochlorination of the filtered wastewater, that permit to recycle the treated water to the flush and use the same water during several days and months without adding new drinkable water. The digested sludge can then be valorized and excess water from the process might be used for cleaning or for watering public gardens and plants. This study permitted to give theoretical data about the inlet and outlet compounds of the system and to optimize the autonomy of the system and the quality of the treated water. It was obtained that for a frequency of 94 uses per day and if the excess clean water can be regularly emptied, the autonomy of the system can reach 435 days with an initial quantity of water of 1.32m3 before to empty the sludges. A Life Cycle Assessment (LCA) of the complete toilet was also realized for a use in a public market in Grigny, France. The WeCo internal purpose of this LCA was to do a first estimation of the environmental impacts of the system to localize and reduce them. It was also to determine if the system is environmentally competitive with the conventional wastewater treatment plants and with the existing autonomous sanitations as chemical toilets. Results shown that most impacts are coming from the high quantity of stainless-steel used for the container structure and from the energy used, especially during the wastewater treatment. It was also established that WeCo toilets have bigger environmental impacts than chemical toilets, possibly due to its more complex chain of production.| File | Dimensione | Formato | |
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https://hdl.handle.net/10589/165024