Abstract
In recent times, the practice of reverse osmosis (RO) membrane technology has become a feasible alternative tool for the wastewater reclamation and reuse. In this research we investigated the applicability of a commercial polyamide RO element to the treatment of municipal sewage-based synthetic wastewater contaminated with nitrite, nitrate, iron, and manganese. The results showed that the RO element achieved the complete removal of BOD, COD, and total coliform. Besides, the ions rejection rates were 98% for iron, 97% for manganese, 93% for chloride, 80% for nitrite, 77% for nitrate, and 45% for ammonia, respectively. Although, dissolved matters in feed water did not cause any significant fouling, organic aggregates and inorganic particles like iron (Fe) colloids decreased the permeate flux of the membrane. The permeate flux of membranes fouled by organic aggregates was successfully recovered to 79% of the initial flux by backwashing from the concentrate port with sodium hydroxide (NaOH) solution at the concentration of 1,000 mg-NaOH/L. The efficiency of NaOH in permeate flux recovery was inferred to be owing to hydrolyzation and solubilization of organic matter by NaOH. On the contrary, the permeate flux fouled by Fe colloids was completely recovered, when backwashing with the deionized water was applied just after the fouling, which suggested that the membrane fouling by Fe colloids was mainly caused by the physical clogging in the membrane.
Highlights
The water demand is increasing more rapidly than the population growth
We examined the applicability of a commercially available polyamide Reverse Osmosis (RO) element to the treatment of synthetic wastewater contaminated with nitrite, nitrate, iron, manganese and municipal sewage-derived contaminants, and sought an effective permeate flux recovery method for a fouled membrane
The permeate water quality of the RO treatment is within the Bangladesh permissible drinking water quality standards except NH4+ [26]
Summary
The water demand is increasing more rapidly than the population growth. As a result, water reuse and recycling approaches under the sustainable development concept have become indispensable for the future generations [1]. Conventional treatment processes like activated sludge processes have been widely used for the water treatment, in most of the cases these processes are inefficient in removing part of hydrophilic organic compounds such as disinfection by-products and pharmaceutical compounds [2]. In these cases, reverse osmosis (RO) system can be used as a potential candidate, which can remove various solutes through charge repulsion and size exclusion mechanism. In membrane technologies membrane fouling is the most significant factor that limiting their applications to the water and wastewater treatment. The main causes of fouling and an effective method for successive permeate flux recovery (PFR) technique were discussed
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Schedule a callMore From: International Journal of Water and Wastewater Treatment ( ISSN 2381-5299 )
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