University of Southampton

Alumnus, School of Civil Engineering and the Environment

Thesis Title: Derivation of Kinetic Parameters for a synthetic wastewater treated in an UASB reactor (at mesopullic temperatures)

About

Synthetic wastewaters facilitate laboratory and pilot scale researches with consistent supply of feed in the circumstances of inconsistent supply of real wastewater. How representative are these synthetic wastewater of the real wastewateris a serious concern. This research analyses the representativeness of the synthetic wastewater (Whalley 2008) to the real wastewater and predits the performance ofthe reactor based on simple kinetic model.

Using the granule-sludge from a paper-mill wastewater treatment plant as the inoculums 4 UASB reactors at mesophillic temperatures, were fed with synthetic wastewater {yeast (23g), urea (2.14g), full cream milk (UHT sterilised) (144ml), sugar (granulated white) (11.5g), blood (freeze dried) (5.75g), Ammonium phosphate (3.4g) and trace elements (1ml) in 1000ml}. Reactors were left to stabiliza at an intended Organic Loading Rate (OLR) from 1 - 6 gCOD/l.day for three weeks at constant HRT (1day) and the influent and effluent quality and gas production were monitored. The treatability of synthetic wastewater is comparable to that of real sewage (Behling, et al., 1997: Uemura & Harada, 2000) for a range of OLRs of 1 - 3 gCOD/l.day (Specific Methane Production - SMP: 0.3 & 0.16 - 0.27 lCH4/g.COD_treated; Specific Biogas Production - SBP: 0.36 & 0.4 lBiogas/gCOD_treated; Effluent Chemical Oxygen Demand - CODe: 48 & 49 - 60 mgCOD/l respectively).

Based on the mean observations of the reactors at 1 - 5 gCOD/l.day, two mathematical models were developed with a correlation coefficient of 1.0000 and 0.9997 to predict SMP and CODe. The predictions based on the models forsee a failure of the reactors when run at 8 to 9 gCOD/l.day (performance lowering to ~ 0.1 l/gCOD_treated of SMP and greater than 3000 mgCOD/l for CODe). COD removed both in terms of Soluble COD (CODs) and Total COD (CODt) revealed a linear stretch, which was also observed by Uemura (Uemura & Harada, 2000) for real sewage. Volatile Fatty Acids (VFA) were below 30ppm for OLRs 4 gCOD/l.day and less, and was around 45 ppm (only acetic acid) for 5 gCOD/l.day loading.

Contact Information