Compared to the conventional activated sludge process, there are some advantages for biological aerated filter (BAF) such as: with high organic loading, small footprint (approximately takes 1/3 of the activated sludge process’s footprint), low capital cost (approximately 30% less), no bulking sludge, high oxygen transferring efficiency and better effluent quality.
BAF combined biological oxidation and solids removal, so there is normally no requirement for the secondary clarifier. Its typical features including high volume load, hydraulic load, less capital cost, high effluent quality, and low operational cost etc.
However, the conventional BAF is often applied with granular ceramic carrier, which causes some disadvantages, such as blockage, high amount of backwashing water consumption and hardly maintenance etc.
To avoid these disadvantages of conventional BAF, Highnew has developed a new type of BAF (HN- HIPBIOFILTER).
Comparison of the conventional BAF with HN- HIPBIOFILTER
| Conventional BAF | HN-HIPBIOFILTER |
Specific surface area | Normal | High，approximately 10×104m2/m3 |
Biomass within fillers | Normal | Biomass can be between 25～40g/L |
Porosity | >36% | >85% |
Surface features | None hydrophilic | Hydrophilic with active groups on the surface |
Blocking | Easy to be blocked and requires periodically cleaning | Hardly to be blocked as the carriers are in semi-fluidization form |
Life span | Approx. 5 years | Over 10 years |
Handling | Difficult to install | Easy to install with directly pour in |
Maintenance | Difficult | Easy, carriers is in a light weight |
Supporting layer | Required | No supporting layer required (patented) |
Performance | Well | Great. With effluent BOD5≤5mg/L, NH4-N≤1mg/L. Over 95% of ammonia nitrogen can be removed. |
DO Utilization | Normal | High porosity. balanced water and air distribution. DO transmitting is highly efficient |
Back flushing | Back flush by air and water. with very high frequency | Just air flushing. No pump required. Less flushing water is consumed. At the meantime, the blower can be use for multiple purposes includes process aeration, and air scouring. Low flushing frequency: once or twice a week. |
Back flushing nozzles | Required | Not required. A perforated tube is used for back flushing |
Capital cost | High | Low, as no requirement for back flushing systems and one blower used for multi purposes. |
Back flushing tank | Required | No required |
Summary
Ø Compared to ceramic carriers, the special Highnew’s new carriers hardly to be blocked with a stable performance.
Ø High DO transmitting and utilization rate.
Ø High biomass per unit volume with a little impact on a surge loading and high effluent quality.
Ø Easy to be installed;
Ø No supporting layer required.
Ø No backwash tank required.
Ø Capital cost is low with a lower operational cost;
Comparison of the operation between conventional BAF and HN-HIPBIOFILTER after years
Aeration of conventional BAF Aeration of HN- HIPBIOFILTER