Volume No. 10 Issue No.: 3 Page No.: 476-485 Jan-Mar 2016

 

PERFORMANCE AND SLUDGE CHARACTERISTICS DURING START-UP OF UASB REACTOR USING PHARMACEUTICAL WASTE WATER

 

Sawaiker U. G.

Department of Civil Engineering, Goa College of Engineering, Farmagudi, Ponda, Goa (INDIA)

 

Received on : September 10, 2015

 

ABSTRACT

 

The feasibility of using Upflow Anaerobic Sludge Blanket (UASB) reactor for the treatment of pharmaceutical wastewater was explored at HRT of 24 h. The UASB reactors were fed with diluted raw pharmaceutical wastewater for first 270 days with stepwise increase in organic loading from 0.5 - 3.3 kg COD/m3/d. During this period, the reactor achieved a maximum removal efficiency of 91% of total Chemical Oxygen Demand (COD) and biogas formation upto12 L/d. The performance of the reactors was not satisfactory with raw pharmaceutical wastewater over a longer period. Hence, the reactors were subsequently fed with simulated synthetic pharmaceutical wastewater containing the solvents present in the said pharmaceutical effluent contributing the major organic load. An intermediary period between this switch over was characterized by development of biomass with sodium acetate as a sole source of carbon and energy. During acclamation phase, with synthetic wastewater organic loading was stepwise increased from 3.0 9.0 kg COD/m3/d. Reactor R1 was used as control. Acetone was introduced in reactor R2 with initial concentration of 150 mg/L and stepwise increased to 1003 mg/L after getting the consistent removal at each step. Similarly, methanol and cyclohexane were introduced in reactors R3 and R4 with initial concentrations of 200 mg/L to 1160 mg/L and 100 mg/L to 675 mg/L respectively. Acetone and methanol were successfully degraded in UASB reactors giving more than 99.64% removal up to organic loading of 4.5 kg COD/m3/d and later decrease in efficiency was observed up to 97 % for the increase in organic loading to 9.0 kg COD/ m3/d. Cyclohexane being less soluble in water, the results showed large variation in its influent and effluent concentrations. The long time to reach the initial start-up period seemed to be responsible for the large variation in the day-to-day characteristics of the raw pharmaceutical wastewater. It is thus suggested that process optimization should focus on shortening the time needed to reach the start-up period and acclimation up to the actual organic load present in a typical pharmaceutical wastewater. Reactors started with simulated synthetic wastewater achieved better biodegradation of the waste, compared to the reactors operated using raw pharmaceutical wastewater, the overall performance of the latter were better than the performance of the former.

 

Keywords : Wastewater characteristics, Start-up, Acclimation, Organic loading rate, UASB

 

 

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