ENHANCING PRODUCED WATER QUALITY USING MODIFIED ACTIVATED CARBON

Abstract

The formation produced water from natural gas production process in the North field offshore considered largest volume of waste water in Qatar, which could be considered a potential benefits source for the industry as well as for other domestic uses if it was treated properly, taking in to consideration economical cost and conditions aspects. This project aims to study the physical and chemical characterizations of the produced water associated with natural gas from the North field, in the same time examine the removal of major inorganic and organic pollutants and heavy metals from the produced water by using different treatment method such as the use of sand filtration, activated carbon filtration and modified activated carbon filtration. Samples of produced water were collected from the North field offshore gas production platforms and analyzed to examine the physical and chemical characterizations of the produced water, the result were compared with the chemical composition of other field produced water, the concentration were within the range among other field except for sulfide and treatment chemical production (additive chemicals) concentrations. The average results briefly showing that, pH , COD, TOC, BOD, conductivity, sulfide, oil and grease (HEM) and total nitrogen parameters as follows: 4.43 , 10496.6 mg/l , 2405 mg/l , 1034 mg/l 7035 µs/cm ,326.3 mg/l ,40.5 mg/l, 47.4 mg/l respectively. Also the study includes other characterizations such as organic acids, phenolic, B.T.E.X, production Chemicals (Additive Chemicals), inorganic anions, metals and cations and the average values of the B.T.E.X (Benzene, Toluene, Ethyl Benzene and Xylene) were found as the following 11170 ppb, 278.1 ppb, 4648.6 ppb and 1156.8 ppb respectively. After the sand filtration (SF) the removal efficiency of the TSS , COD, acetate, propionate, corrosion inhibitor and TN (total nitrogen) parameters were the following 77.5% ,10.1%, 7.82 %, 4.5%, 94.1% and 63.7 % respectively. Meanwhile, the removal efficiency of the B.T.E.X (Benzene, Ethyl Benzene and Xylene) found as the follows: 93.14%, 99.8% and 96.7% except for Toluene was 27.6%. The highest removal efficiency for the metals and cations was for iron, chromium and manganese were as the follows 99.5%, 97.5% and 95.8% respectively. Activated carbon filtration was found to be more efficient to remove COD and TOC with 23.7% and 30.7% respectively among the three media. Regarding the removal efficiency of the Activated Carbon for the organic acid was the highest for the acetate and propionate with 83.6% and 88.7% respectively and for the inorganic ions- phosphate the removal efficiency was 94.9%. Also the AC showed removal for some metals such as zinc, copper, boron, nickel, iron and chromium and highest removal efficiency more than 97% for the all B.T.E.X compound except for the Ethyl benzene was 76.9%. Modified Activated Carbon was found to be more efficient to reduce the TOC with 31.1% whereas the COD concentration increased by 12.6%. MAC showed also removal efficiency for the inorganic ions phosphate and sulphate with 94.9 and 48.4% respectively. For the metals, MAC was more efficient than the AC to reduce the zinc, molybdenum and boron concentration and less efficient than AC to reduce copper and acetate (Organic acid), Regarding the B.T.E.X removal efficiency is similar to AC more than 98% except for the Ethyl benzene which was 92.3% higher than AC 76.9%.