Effect of media on treatment of settled domestic sewage using hybridized anaerobic baffled reactors

الملخص EN

This research work aimed at obtaining a low cost sustainable technology for domestic wastewater treatment for Egyptian rural areas.

To make this come through, a high rate hybirdized anaerobic baffled reactor (HABR) was pilot tested for a period of about 18 months in order to assess the state of art and the technical and economic efficiency of this system.

This pilot reactor consisted of four reactors with different media (HABR1, HABR2, HABR3 and HABR4) were constructed and each reactor had a total volume of 800 liters and consists of four compartments.

Plastic media and gravel were used and had specific surface area of 100 and 80 m2 /m3 respectively.

The average influent COD concentration was about 300 mg/l.

The overall HRTs tested were 3.5, 2.5, 1.0 and 0.5 days with average influent organic loadings in the range from 0.05 to 0.25 Kg BOD5/m3.day.

High substrate removal rates can be achieved in a HABR fed with low substrate levels of only 300 mg/lit of COD.

At an HRT of 3.5 days, HABR1 with plastic media gave an average BOD5 removal rate of 79% with an effluent of 25 mg/lit.

This was the highest removal value recorded as the other reactors HABR2, HABR3 and HABR4 gave 60.5%, 71.5% and 75.6% respectively for the same HRT.

In a likewise manner, the COD removal rates recorded at the same HRT were 85.7%, 80%, 83.3% and 85.7% respectively.

Suspended solids removal rates were the highest and recorded a value of 90.3% for a HRT of 3.5 days for HABR1.

At the same HRT the removal rates for HABR2, HABR3 and HABR4 were 76.8%, 86.5% and 89% respectively.

For HABR1 the BOD5 removal rates dropped from 79% at a HRT of 3.5 days to about 50.5% at a HRT of 0.5 days.

This was also the case with the other three reactors and the lowest removal rate recorded was 33.7% for HABR2 at an HRT of 0.5 days.

The highest COD value recorded was at a HRT of 0.5 days for HABR2 with a value of 101.2 mg/lit.

While the highest SS value recorded was 72.4 mg/lit with a percentage removal of 58.8% for HABR3 at a HRT of 0.5 days.

This system provides potential attractive possibilities for application in small communities with a population of less than 5000 capita.