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Tylosin has been considered inhibiting COD removal in anaerobic digestion. In this study it is proven that this is not always the case. Accordingly, elevated concentrations of Tylosin (100-800mgL-1) could be tolerated by the anaerobic system. The influence of Tylosin concentrations on an up-flow anaerobic stage reactor (UASR) was assessed using additions of Tylosin phosphate concentrate. Results showed high efficiency for COD removal (average 93%) when Tylosin was present at concentrations ranging from 0 to 400 mg L-1. However, at Tylosin concentrations of 600 and 800 mg L-1 treatment efficiency declined to 85% and 75% removal respectively. The impact of Tylosin concentrations on archaeal activity were investigated and the analysis revealed that archaeal cells dominated the reactor, confirming that there was no detectable inhibition of the methanogens at Tylosin levels between 100 and 400mg L-1. Nevertheless, the investigation showed a slight reduction in the number of methanogens at Tylosin levels of 600 and 800 mg L-1. These results demonstrated that the methanogens were well adapted to Tylosin. It would not be expected that the process performance of the UASR would be affected, not even at a level well in excess of those appearing in real wastewater from a Tylosin production site.

-The present investigation was aimed at determining the impact of the macrolide antibiotic Tylosin in reduced HRT at constant organic loading rate (OLR) by varying feed substrate concentration in an up-flow anaerobic stage reactor (UASR). The antibiotic concentration was maintained at 200 mg.L , by varying feed substrate concentration to the UASR and the HRT was decreased gradually from 4 to 1 d. Throughout the operation period, brewery wastewater was used as simple feed substrate to elevate the concentration of easily biodegradable carbon in comparison with the concentrations of more recalcitrant Tylosin substrate. The reactor alkalinity was controlled in all the stages of UASR by adding 1000 -2000 mg.L -1 CaCO 3 . Results showed the total COD removal efficiency at 4 d HRT was around 92%, after which point there was a slight decrease at 3 and 2 d HRT (average 82%), and this was reduced further (average 77%) at a HRT of 1 d. The UASR showed stable operation with effluent volatile fatty acid (VFA) less than 300 mg.L -1 throughout the experimental period (HRT 4 -1 d). Moreover, the average methane yield (CH 4 .kg COD r -1 ) showed a relatively constant profile and was largely unaffected by HRT in all the stages of UASR. These results show that bacteria were readily adapted to wastewater containing Tylosin at lower HRTs and did not affect the reactor performance substantially.

Effluents from manufacturing operations in the pharmaceutical industry, such as antibiotic formulation, usually contain recalcitrant compounds. An approach towards appropriate technology for the treatment of pharmaceutical wastewaters has become imperative due to strict water quality legislation for environmental protection. In the present study, an Up-Flow Anaerobic Stage Reactor (UASR) and a Porous Membrane Activated Sludge Reactor (PMASR), operating in series, were used to treat pharmaceutical wastewater containing the macrolide antibiotic Tylosin. The performance of UASR treating real pharmaceutical wastewater at various organic loading rates (OLR) (0.43 to 3.73 kg COD.m -3 .d -1 ) was investigated. Effluent from the UASR was passed directly into a PMASR system in a continuous process. At a reactor OLR of 1.86 kg COD.m -3 .d -1 (hydraulic retention time (HRT), 4 d), the soluble COD reduction was around 70 -75% (average specific degradation rate (SDR), 1.29 kg COD.m -3 .d -1 ) an average of 95% Tylosin reduction was achieved in the UASR. During this period, the soluble COD removal efficiency of the PMASR was 63-69% (average SDR, 0.37 kg COD.m -3 .d -1 ). The combined UASR -PMASR treatment system was slightly more effective with 87-90% COD and average 97% Tylosin removal. The results indicate successful treatment of the pharmaceutical wastewater, and confirm Tylosin degradation, providing further evidence that Tylosin can be degraded efficiently in anaerobic-aerobic environments.