John P. MacHarg of the American Water Works Assoc writes articles relating to Energy Recovery Inc., a Company that provides affordable with the PX Pressure Exchanger which reduces energy costs up to 98%.
How To Design And Operate A PX? System Part 1 However on larger plants using open seawater intakes with large-scale gravity feed media filtration systems, and when the chemical additions associated with coagulation are significant operating cost...... Source : How Is The Environment Pg. 32
