Companies periodically appear on the Georgian market promising consumers biological wastewater treatment plants with 98% efficiency. They also claim that their proposed products produce no sludge, require no sludge removal, and completely eliminate pollution.
Such a treatment system is a scientific absurdity due to the following reasons:
1. If the system does not produce sludge, it is not operating effectively
Currently, three main biological treatment technologies are used in the Georgian market: Activated Sludge, Extended Aeration System, and Sequence Batch Reactor (SBR). All three technologies rely on the same principle: during the treatment process, pollutants (mainly organic pollution, total suspended solids, nitrogen compounds, and phosphorus) are separated from the water. Matter physically cannot just "disappear".
The separated organic pollution is consumed as food by microorganisms present in the water. For every unit of pollution consumed, a corresponding new unit of bacterial mass—excess sludge—is generated. This means that mass balance is maintained, which is a fundamental law of physics.
A system that does not require pumping out excess sludge would need to have an infinite Sludge Retention Time (SRT), which is physically impossible in a finite-volume tank.
Critical parameters, such as the concentration of Mixed Liquor Suspended Solids (MLSS) in the bioreactor and alkalinity, remain within permissible limits only through periodic sludge removal.
For the technologies available on the Georgian market, the reality is simple: the equipment either separates pollution from the water and generates sludge, or it fails to perform its function, pollutes the environment, and consequently produces no sludge.
2. The Myth of 98% Efficiency
When evaluating the technical specifications of biological treatment plants, various companies on the Georgian market frequently use abstract phrases like "98% efficiency," yet they deliberately avoid specifying which parameter they are referring to. The aforementioned technologies used in the Georgian market, under proper operating conditions, perform treatment with the following efficiency:
| Parameter | Influent Wastewater | Activated Sludge | Extended Aeration | Sequence Batch Reactor (SBR) |
| BOD5 |
350 mg/L |
25 mg/L (92.8%) |
15 mg/L (95.7%) |
≤ 15 mg/L (≥ 95.7%) |
| COD |
750 mg/L |
120 mg/L (84.0%) |
80 mg/L (89.3%) |
≤ 75 mg/L (≥ 90.0%) |
| TSS |
400 mg/L |
30 mg/L (92.5%) |
20 mg/L (95.0%) |
≤ 15 mg/L (≥ 96.2%) |
| Total N |
70 mg/L |
40 mg/L (42.8%) |
25 mg/L (64.3%) |
≤ 25 mg/L (≥ 64.3%) |
| Total P |
12 mg/L |
8 mg/L (33.3%) |
6 mg/L (50.0%) |
≤ 2 mg/L (≥ 83.3%) |
The cited reduction percentages are verified against the influent wastewater load standards defined by the German standard DWA-A 198 and are based on norms recognized by the German Institute for Building Technology (DIBt). The treatment efficiency percentages are certified by the German Stand der Technik (the highest technological standard adopted in Germany) and by independent institutes, such as the Aachen-based PiA (Prüfinstitut für Abwassertechnik) Wastewater Technology Testing and Certification Institute, under certification number DIN EN 12566-3.
However, these results are achieved only by treatment systems certified in developed countries by reputable organizations such as PIA GmbH. Manufacturers who fail to pass such rigorous testing see no other option but to sell their products in developing countries, where real quality requirements for wastewater treatment systems are still lacking.
Consequently, not a single wastewater system available on the Georgian market achieves 98% efficiency in even a single component of the treatment parameters.
3. The Myth of "15-Minute Maintenance Once Every 3 Years"
According to international engineering standards EN 12566-3 (+ DWA-A 222), in extended aeration systems without primary sedimentation, the excess dry matter production per capita is approximately 40 grams/day. For 15 residents, this figure amounts to 0.6 kg per day, which equates to 219 kg of dry sludge per year. For the same number of residents, the annual volume of wet sludge amounts to 15 m3 (at a sludge concentration of 15 kg/m3, which is typical for such systems).
Even if the system features an anaerobic zone that partially digests the sludge, several cubic meters of sediment still accumulate in the tank annually. A treatment system physically cannot contain the sludge accumulated over 3 years unless its volume is at least 45 m3, whereas the average volume of such systems is only 3 - 10 m3. In compliance with engineering standards, the system needs to be emptied of sludge every 12 to 18 months.
The promise that you will not have to touch the system for 3 years guarantees that the system will switch to an anaerobic (putrefaction) mode and begin generating unpleasant odors within the very first year of operation. Without sludge disposal, the MLSS concentration increases, oxygen demand exceeds the delivery capacity of the air compressor, the Dissolved Oxygen (DO) level drops below 2 mg/L, and the aeration tank transitions into an anaerobic (septic) regime, leading to the formation of H₂S and the development of foul odors.
