Using tertiary-treated municipal wastewater as makeup water by reverse osmosis membrane

Abstract

A B S T R A C TThe objective of this research was to study the possibility of using reclaimed municipal wastewater in cooling tower by treating the water using reverse osmosis (RO) membrane. In this study, RO membrane was operated at initial flow rate of 6.3 m 3 /d, whereas the initial transmembrane pressure (TMP) was at 116 psi. During the operating period, permeate flux slightly decreased to 4.8 m 3 /day with the increase of TMP up to 127 psi and membrane fouling resistance of 3.34E + 12 m −1 . Major membrane fouling mechanism was complete blocking followed by standard blocking and cake layer formation. Average permeate characteristics were 36.3 μS/cm of conductivity, 42.3 mg/L of TDS, 4.4 mg/L of hardness, 22.7 mg/L as CaCO 3 of alkalinity, 0.002 mg/L of iron, 0.05 mg/L as CaCO 3 , 1.5 mg/L of chloride, 2.1 mg/L of silica, and there was no phosphate passing through RO membrane. Percent rejections compared to UF treated wastewater were in the range of 90.2-99.9% except for silica where rejection was only 85.1%. Scaling and corrosion index was studied in terms of Langelier saturation index (LSI) and Ryznar stability index (RSI). Without RO membrane, LSI value was −0.59 and RSI value was 8.5. With RO membrane, LSI value was −5.0 and RSI value was 17.0. From calculation of cycles of blowdown, it was found that when using the membrane, the cycles increased from 2.3 to 44 cycles. This, then, resulted in reduction of makeup water from 379.0 to 221.2 m 3 /d, a decrease by 41.6%. Payback period of installation and operation of RO membrane system was 14 months.

Electrolysis of Tertiary Water Effluents─a Pathway to Green Hydrogen

“…RO can effectively exclude anionic and cationic salts to reduce the total amount of dissolved solids in water. RO has been widely used in the treatment of tertiary wastewater. − Analysis on seawater RO indicates that RO represents only 3 and 0.2% of the direct capital cost and operating cost of PEM electrolysis plants, respectively . It should be noted that tertiary effluents require less purification than seawater, and this may lower the capital and operating costs of RO units …”

Hidroquímica Y Contaminantes Emergentes en Aguas Residuales Urbano Industriales De Morelia, Michoacán, México

“…En los efluentes la CE y el B se redujeron en 13 y 33 %, respectivamente, en comparación con los influentes; la RAS no mostró variación indicando que la relación entre los cationes solubles Ca 2+ , Mg 2+ y Na + no fue afectada por el proceso de tratamiento en la PTAR. La baja eficiencia para reducir las sales solubles es característica de las PTAR que utilizan procesos primarios y secundarios (lodos activados), requiriéndose para aumentarla el empleo de procesos terciarios como membranas de intercambio iónico, ósmosis inversa o ultrafiltración, entre otros (Kornboonraksa 2016 1994). Estos efluentes pueden reutilizarse en el riego agrícola en suelos de buen drenaje, donde las sales que se adicionan con el agua de riego se lixivian reduciendo su acumulación en el perfil del suelo.…”

Activated carbon incorporation on forward osmosis membrane surface for enhanced performance

“…Among the technologies employed, membrane separation is a promising option to address the water crisis in the 21st century (Sun et al 2014). In particular, the high pressure driven reverse osmosis (RO) process has been extensively employed for both large scale desalination of brackish and seawater as well as for the tertiary treatment of municipal wastewater (Kornboonraksa 2016). Though well-established, RO is beset by high cost resulting from being energy-intensive; in addition, the membrane fouling propensity requires periodic, costly membrane replacement (Liyanaarachchi et al 2014;Motsa et al 2014).…”