A water purification system comprises a bioreaction subsystem receiving contaminated input effluent and having a gas-lift anaerobic membrane bioreactor removing urea and organic matter to create a first effluent. A light-treatment subsystem receives the first effluent and exposes the first effluent to UV light to create a second effluent free from microorganisms. A reactor subsystem fluidically connects an ammonia-reducing reactor to the UV output and receives UV-treated second effluent and has a struvite regenerator connected to the ammonia-reducing reactor output, separating ammonia from the second effluent in the ammonia-reducing reactor, and outputting the ammonia. A separation subsystem fluidically connects to the reactor output and receives the second effluent substantially free from ammonia and has a continuous electro-deionization device separating brine/salts from the second effluent to produce potable water. A closed-loop includes an ammonia-converting subsystem and a sequential fertilizer producer.