Life cycle assessment of new bio-based coagulant production for sustainable wastewater treatment

Wastewater effluents are great contributors to the ubiquitous problem of water contamination. Seen as one of the "greener" technology solutions, coagulation/flocculation technology utilises alternative coagulants of "green" origin. A life cycle assessment was performed in order to provide an environmental performance evaluation of three differently produced coagulants obtained from common bean seeds (Phaseolus vulgaris). The aim of the research was to compare production processes by identifying their hot spots and to determine which one was preferable from the ecological aspect. Furthermore, coagulation activity was determined and presented. The production processes included classic and ultrasound extraction, performed with 0.5 M NaCl solution as an extraction agent, and spray drying process conducted without or with carrier material (gum Arabic). Coagulant obtained by ultrasound extraction and dried with the help of carrier material, showed the lowest impact on the environment (around 50% lower than coagulants dried without carrier) while achieving high coagulation activity (61.5% of initial turbidity was reduced by the usage of 1 mL/L coagulant concentration). The life cycle assessment showed the highest impact from the production of all three types of coagulants originated from the electricity consumption mostly within spray drying phase (around 90% of total environmental impact originated from the mentioned phase). The coagulant production process has a relatively low environmental burden due to low chemical consumption, and it consisted of only a few simple production steps. Furthermore, possible improvements and optimisation of the production process hot spots were considered.