Using modified clay-chitosan composite filter as a second stage in the conventional iron and manganese removal plant system to eliminate permanent hardness anions in drinkable groundwater

Abstract

The presence of permanent hardness ions (sulfate and chloride) in drinkable water in large amounts causes many problems, either health effects like bad taste, color, and odor of water or technical effects like the formation of stains and scales in house vessels and pipelines. This paper presented an applicable concept for using a newly prepared composite composed of modified local clay and locally extracted chitosan as a second-stage filter after pressure sand filters in the conventional iron and manganese removal plant to remove sulfate and chloride from raw drinkable groundwater. The morphology and structure of the raw samples and the modified clay/chitosan (MCCh) composite were explored by using different techniques. Also, this study deals with the experimental batch and column studies to examine the prepared composite ability to remove permanent hardness ions. The adsorption capacity of MCCh for sulfate and chloride ions was investigated under various conditions, e.g., temperature, pH, contact time, various initial concentrations, and adsorbent dosage. Results indicated that the MCCh composite exhibited a good adsorption capacity (3.2 mg/g) for permanent hardness ions at optimized conditions, a pH range of 3–6.5, and 60 min contact time. Regeneration experiments were performed for the MCCh composite for 6 cycles. The % of sulfate and chloride ions removal reached about 92% at a powerful acidic solution and about 70% at a neutral pH for really applied raw groundwater.

Keywords

• Permanent hardness
• Chloride
• Sulfate
• Chitosan
• Modified clay
• Composite