Treatment of Refinery Wastewaters Using Various Modified Activated Sludge Process

Biological prosesses for treating refinery industry wastewater for re-use were studied. A pilot-scale biological reactor was constructed to simulate the activated sludge treatment process. Actual refinery industry wastewater collected from a regional refinery and spiked with additions of selected priority organics was fed at a rate of 1.3 liters/hour into a 6'-liter pilot plant having a hydraulic retention time of 4 hours. Activated sludge (AS) which was augmented by additions of powdered activated carbon (PAC) at dosages of 10, 50 and 120 mg/L was evaluated. The AS process removed 70-80% of the B005 , COO and TDC. With the addition of PAC, removal efficiencies of the indicator compounds rose to 80-95%. The sludge physical parameters and kinetic constants were determined with and without the addition of PAC to the AS. PAC additions to the AS increased the amount of biomass in the reactor. Volatile compounds (benzene, chloroform, ethylbenzene, toluene, m-xylene and o-xylene) were removed from the reactor by volatilization which o c c u r r e d fr om a i r st r i pp i n g . PAC alone (without AS) was primarily responsible for removing base and acid/neutralextractabl e compounds (2,4-dimethylphenol, fluorene, naphthalene and pyrene).

Characteristics of the Refinery Industry                      The inshore water of SIA is very shallow. The water depth offshore of SIA averages about 5 meters within 1 km from the coast line. Thus, most discharged pollutants are not well mixed or diluted with sea water (58).
The discharged industrial wastewaters in the SIA inshore water are diluted with seawater from the cooling water from the pumping stations. The concentration of pollutants in the wastewater will be affected by mixing with seawater in that the concentrations are reduced but the mass loading of the organic pollutants will not be reduced. is collected and routed to the sour stripping unit, where the pre-treated water goes to the oil separator known as There are now pl ans to improve the present situation and lower pollutant loads by improving the ' pr i mar y tr ea tm en t pl an ts , b u t s i n c e th e w a stew a t er fl ow s will also increase, the net improvement in water quality will not be significant. Therefore, this study was initiated to investigate methods of treating priority pollutants found in SIA refinery industry wastewater using a powdered activated carbon with activated sludge as a second a r y treatm en t. However, Kincannon et al. (39) have shown that in addition to those compounds, benzene, methylchloride and 1,2-dichlorobenzene were completely stripped under identical conditions without a biological treatment.
Tr av e r s e t a l . ( 6 9 )          Zimpro (33) showed that addition of PAC in an activated sludge treatment would improve BOO removal from 58% to 97% and COD removal from 58% to 97%, but the suspended solids removal increased from 73% to 91%. Color was also reduced by between 150 to 500 APHA units. ln the industrial sector, however, PAC reduced TDC and color by 93 and 98% while a biological treatment removed only 67 and 27%, respectively.

Priority Pollutants
Specific organic compounds found in wastewaters are known as "priority pollutants". In the literature, investigators were concerned with defining better analytical methods for measuring and making assessments on the pres~nce of these chemical compounds.
Keith et al.

Industrial Wastewater Reclamation and Reuse
For years, many countries in the world have begun to reuse domestic and wastewater. The role of using reclaimed wastewater will increase in the future as drinkable water becomes scarce and expensive.
Wastewater is a valuable source and could be used when treated and managed properly. Treated wastewater was used directly to irrigate landscapes and part of the water was used by the city for nonpotable uses. The project will be run for 5 years to study its performance. Upon completion, the authority will be able to answer many questions related to future w a t e r r e u.s e . DeBoer (14)  therefore, reuse of the municipal wastewater was being considered as a source to meet rapid growth in the community. Investigations were conducted to determine the most feasible way to use the reclaimed water.
The plan was to reuse the reclaimed water for a golf course, a greenbelt area, as well as for residential and commercial development.
Crook (12) discussed water reuse in California within the past few years. California encouraged such uses as 35 irrigation.
Irrigation accounted for approximately 80% of the total quantity of wastewater reclaimed. Health criterias were established for various uses including irrigation, impoundments, and groundwater recharge.
Corssmit (11) reported on financing plans and price schedules for reused water.
For the reuse project to be successful, four feasibility tests should be fol 1 owed: (    It has a maximum of 75% of the particles passing through a 325-mesh screen.
A BL type PAC recommended by the carbon manufacturer was selected for this study.
The specifications for PAC were provided by the manufacturer (Table 3.1.1).

Experimental Steps
The experimental phases were run at 3, 6                 1. Run normal suspended sol ids tests using a 10 ml sample, dry it at 6oo 0 c for one hour, then measure the suspended ash.
2. To another 10 ml aliqout of the sample, add 20 ml of concentrated nitric acid.
3. Heat the acidified sample to just under boiling.
4. Continue heating until the sample volume has been reduced to approximately 10 ml.
5. Cool the sample to room temperature. Chemical analyses of grab composite samples were made

Selection of Priority Pollutants
According to the regulatory agency (Kuwait          The term um in Equation 6.3.2 can be defined as: Metcalf (48) showed that because of the quantity of new cells produced for a given substrate, the following relationships have been developed between the rate of substrate utilization and the rate of growth as follows: rt was important to fill each test tube less than halfway ' to allow adequate air space. Immediately after collection, the sample was analyzed, beginning with 160X phase contrast microscopy, which requires only a small volume of sample(< l ml). Each sample was pl aced on a glass slide and covered with a thin glass cover; no special preparation such as staining was required.
The sample was examined at a magnification of 160X for the types, relative amounts, and growth of microorganisms in the AS. No attempt was made in this study to estimate the total number or the sizes of each microorganism.

6.6.l Materials and Methods
In this experiment, PAC type BL (Calgon Corporation) was used.

1.
A method blank is run every day to make sure that the s y s ~em i s fr e e o f i n t e r f e r e n c e s .

2.
Standards are run for retention times to allow detection of any potential problems.

3.
EPA Quality control check samples are run to insure the accuracy of our analytical system. 27