Info

« Permeate COD B Permeate BOD

Date

Figure 5. Permeate COD and BOD concentrations.

1. Variation of the feed concentrations of ammonia and phosphate. Again reinforcing the need for buffering upstream of a full size plant.

2. Biological phosphate assimilation.

3. Simultaneous nitrification and denitrification caused by an anaerobic nucleus forming in the MLSS, which at higher concentrations became more viscous.

4. Concentrated blood containing up to 50 mg/1 phosphate being added at the start of the study, conditioning the MLSS microbial population enhancing phosphate removal when this high concentration was later removed.

+ Permeate Phosphate as P ■ Permeate NH4 as N

Date

Figure 6. Permeate ammonia and phosphate concentrations.

Date

+ Permeate Phosphate as P ■ Permeate NH4 as N

Figure 6. Permeate ammonia and phosphate concentrations.

Loading rate on the bioreactor was 6.2 kg COD/mVd, 3.2 kg BOD/m3/d and 0.9 kg COD/m2/d, 0.5 kg BOD/m2/d on the membrane. Samples taken from the permeate and mains water supply to the site showed a large increase in the concentration of dissolved salts in the permeate. Chlorides rose from 68 to 172 mg/1 CI and sodium rose from 47.6 to 127 mg/1 Na. Reuse of the permeate from the MBR in the factory, without further treatment, would create an environment in the bioreactor that would be toxic to the microbial population. However, the permeate was treated using a Reverse Osmosis (RO) plant and caused no fouling to the RO membranes.

2.3 Cost Benefit Analysis

The processing plant where the MBR was trialed currently has DAF pre-treatment before discharge to sewer. Trade effluent bills for a flow of approx. 900 m3/d are circa £300 K per annum and volume discharged is expected to double. Effluent treatment plant on site requires a small footprint, as space is at a premium, and low odours, as the factory is opposite a residential area. Estimated costs of a ZenoGem® membrane bioreactor to treat 1800 m3/d are:

Capital Expenditure - £1,400,000 Operating Expenditure -18.3p/m3 permeate The permeate from the pilot MBR was of a high enough quality to discharge direct to river and savings in trade effluent costs give an estimated payback period of approx. 3 years.

0 0

Post a comment