Advancements of new process systems consisting of magnesium coagulation-precipitation, dissolved air flotation (DAF) clarification, filtration and disinfection are introduced : (a) the use of magnesium carbonate or magnesium chloride for replacing alum, (b) the use of DAF for replacing sedimentation, (c) the use of magnesium coagulation-precipitation, DAF , recarbonation , and filtration for water or wastewater treatment, (d) production and marketing of magnesium and calcium sludge for replacing conventional lime as the soil conditioner or for nutrient removal in a biological treatment plants. Examples and case histories of the sustainable process system include: (a) magnesium coagulant for water purification with total chemical sludge recycle; (b) independent physicochemical wastewater treatment using magnesium coagulant and DAF-filtration for treating wastewaters containing toxic substances; (c) simultaneous removal of ammonium ions and phosphate ions from wastewater by magnesium ions for generating useful waste sludge (Struvite) which can be reused as a fertilizer; (d) chemical sludge reuse elsewhere for toxic chromium reduction; (e) waste chemical sludge reuse for biological nitrification neutralization at chicken and meat processing plants; (f) waste chemical sludge reuse for anaerobic digestion improvement at bakeries; (g) pretreatment of per- and polyfluoroalkyl substance (PFAS) contaminated water prior to granular activated carbon, ion exchange, or membrane filtration; and (h) production and marketing of combined magnesium and calcium sludge as a soil conditioner. The authors’ poem ( FATE IN THIS LIFE 今世缘) is presented in this publication.