TREATMENT OF PRODUCED WATER FROM NIGER DELTA OIL FIELDS USING CHEMICALLY MODIFIED BIO-ADSORBENT

Abstract

The high concentration of salt, organic contaminants and harmful heavy metals found in Produced Water (PW), which is a significant byproduct of oil and gas extraction, pose serious health and environmental risks. In the Niger Delta, poor PW management has resulted in significant ecosystem degradation and contamination of freshwater resources. Conventional PW treatment methods, like chemical precipitation and membrane filtration processes can often be expensive, demand significant energy, and produce additional waste. This study explores the use of chemically modified bio-adsorbents (cassava peel) as a cost-effective and eco-friendly option for eliminating heavy metals from PW.

The adsorbent was crushed and sieved into 63- and 150-micron size. For 24 hours, each of them received a treatment with diluted nitric acid (500 mL at a concentration of 0.4 mol/L) to remove pigments. After filtering, drying, and rinsing with distilled water, the pH was brought to neutral. It was then soaked in diluted H2SO4 (15ml of H2SO4 to 500ml of distilled water). After filtering, drying, and rinsing with distilled water, the pH was brought to neutral. The bio-adsorbents were applied to the PW samples in a batch process and the filtrate was collected at an interval of 30 minutes for analysis for heavy metals determination using an Atomic Absorption Spectrophotometer.

Co, Ni, Mn, and Mg were the metals that were examined. The concentration of the metals was reduced by the bio-adsorbents to 80%, 80%, 55%, and 30% for Co, Ni, Mn and Mg respectively. The adsorption system was also analysed using Langmuir and Freundlich isotherm models.

It was discovered that the better the adsorption result, the finer the adsorbents. An improved outcome was obtained with 63-micron size than with 150-micron size.