HNV type biological treatment plants of domestic wastewater for settlements and newly built quarters


HNV type domestic wastewater treatment plants for settlements and newly built quarters are intended for treatment of domestic or similar wastewater from the kitchen, bathroom, toilet and other similar-purpose facilities.

Substances that cannot enter the treatment plant are as follows:

  • surface wastewater (off the roof, from the yard, etc.);
  • wastewater from a garage and other non-domestic–purpose facilities;
  • water from a basin or other receptacles that are larger than 1m3;
  • chemical substances, entering into sewage system of which is not provided according to their usage (oil products, agrochemical substances, etc.);
  • water after regeneration of filters of softening/removal of iron;
  • chemicals used at home (washing means, bleaches, softeners, degreasers) shall be use as provided in manufacturer recommendations.

1. Manual grating

2. Sand trap

3. Flow collection/distribution well

4. HNV type wastewater treatment plant

5. Sludge thickener

6. Debit measurement well

7. Airblower

Equipment advantages
  • various capacities;
  • high level of treatment (removed up to 98% of pollutants);
  • no internal movable parts to be supervised or replaced;
  • serviceable, light-weight glass-fibre structure (easy transportation);
  • small-size enclosed type products;
  • quiet operation and no offensive odour diffusion;
  • treated discharged water – transparent and odourless;
  • minimum power consumption;
  • easy maintenance and process automation;
  • installation is possible both, under the ground (in case of interference with underground structures) and in a special filling above the ground. 
  • I modification (HNV-P): primary settling vessel, aerobic reactor, secondary settling vessel;
  • II modification (HNV-N): anoxious chamber, aerotank of prolonged aeration, secondary settling vessel.

Modular system of HNV type wastewater treatment plant and additional equipment

HNV-P type treatment plants

The plant of HNV-P modification is constructed from a primary settling vessel, an aerobic reactor, a secondary settling vessel (with a module of thin wall) in one tank. Usually, grating (or a pump crusher) and a sand trap are installed before the plant of HNV-P modification. 
The fed wastewater enters the primary settling vessel. Wastewater is treated for 2 hours in the primary settling vessel. The sludge settled in the settling vessel with the help of the air pump is constantly removed into a separately fitted sludge stabiliser. After the settling vessel, sludge enters the aerobic reactor with the bioload. Biological treatment, i.e. treatment with activated sludge, is based on microorganisms’ activities. Wastewater, requiring treatment, is aerated. Flake forming bacteria (microorganisms) multiply and form groups that cause adherence of protozoots and other bacteria. Microorganisms metabolyse (“eat up” and decompose) and biologically destroy organic substances. Constant feeding of oxygen is required. Purpose of the process is to bind soluble, colloidal and biogenic substances from wastewater into activated sludge and separate activated sludge. Basically, the process of activated sludge is a live system, thus appropriate actions are required. In order to maintain certain necessary microorganisms, appropriate “feeding, growing, multiplication” is required. Sudden changes in working conditions may result in a shock. Thus, the bioload, to which attach microorganisms that cannot be removed by uneven wastewater flows. Excess sludge from the aerobic reactor is removed into the primary settling vessel with the help of the air pump. After the aerobic reactor, the mixture of wastewater and sludge enters the secondary settling vessel with the thin-walled module, from which the settled sludge is returned into the aerobic reactor with the help of the air pump, and the cleared wastewater drains away from the facility. 

Technological schemes of HNV-P type wastewater treatment plants 

I option. HNV-P type wastewater treatment plants amounts from 5m³/p to 24m³/p (in one body) 

 Technological characteristics

II option.  HNV-P type wastewater treatment plants amounts from 25m³/p to 55m³/p (the secondary settling tank in a separate body) 

Technological characteristics

HNV - N type treatment plants

The plant of HNV-N modification constructs from an anoxious chamber, an aerotank of prolonged aeration and a secondary settling vessel in one tank. It is necessary to install a grating (a pump crusher), a sand trap, a septic tank and, on necessity, a grease trap against the plant of HNV-N modification. 
Anoxious aerobic treatment conditions (oxygen from nitrates is used for biological processes), that is inlet wastewater is mixed with the mixture of nitrified sludge, which is fed from the aeration chamber. Nitrate nitrogen is removed from sludge in the anoxious chamber and settlement of sludge is improved (sludge index and danger of denitrification in the secondary settling vessel decrease). After the anoxious chamber wastewater enters the chamber of prolonged aeration (the aeration reactor), where wastewater is aerated and then aerobic wastewater treatment is performed and excess nitrogen oxidizes into nitrates. The mixture of wastewater and sludge from the aerotank enters the secondary settling vessel, where the separated activated sludge returns to the anoxious section, and cleared wastewater discharges from the facility. Excess activated sludge is periodically removed from the facility, when its concentration reaches the maximum permissible concentration in the aerotank. 
The highest wastewater treatment efficiency in achieved in plants of HNV-N modification; they are also easy to service; no green sludge formation, no anaerobic processes take place during wastewater treatment, thus there is no offensive odour diffusion, fully stabilised sludge is removed, due to very low loads of sludge sustained, amounts of excess sludge are lower than of facilities of other modifications. 

Technological schemes of HNV-N type wastewater treatment plants 

I option. HNV-N type wastewater treatment plants amounts from 5m³/p to 24m³/p (in one body) 

Technological characteristics 

II option. HNV-N type wastewater treatment plants amounts from 25m³/p to 55m³/p (the secondary settling tank is in a separate body)