When launching the first sewage treatment plant, our major idea was to offer a solution for the unobjectionable disposal of wastewater directly on the sources of pollution with the possibility of subsequent utilisation of cleaned water for watering or any particular use. This was aimed at estate owner with original sumps (cesspool, septic tanks), but also as a solution when constructing new houses. Following partial development innovations in the course of our production activities, we have been successfully implementing this initial idea of preventive protection of our environment not only in the Czech Republic but also abroad.

The plants enable unobjectionable liquidation of sewage water with fecal solids directly on the sources of pollution (septic tank, cesspool):

* In family houses, small inns, boarding houses,
* Restaurants, pensions, motels, small hotels,
* Lavatories of small production plants, building site outfits, and similar premises with permanent operation.

The treatment plants are designed in three basic sizes for minor sources of contamination. The UH-1,5 version processes 1.500 litres per day, the smaller UH-1 version processes 1.000 litres per day, and the UH-0,5 version processes 500 litres per day.

Cesspools or septic tanks serve as the first mechanical step of cleaning treatment and, at the same time, they represent accumulation space to equalize the quantitative and qualitative disproportion of the inflow.
The recovered water utilizes a gravity chute as an outlet through a gutter, drainage or a soaking area. The most convenient way to utilize recovered water is its double use either for watering or for garden irrigation. HERVA STP saves your money for empty of septic tanks.

The stabilised sludge enables utilization for preparation of compost or directly for fertilizing of flower beds without further need of additional use of solid power fertilizers.
The depth of the pits is not crucial - the patented design of the transporting equipment enables the installation for any depth.

The sewage treatment plants are located in the ground level, directly over the aperture, usually 500 x 500 mm of the existing pit without having to perform any building adjustments.
In case of requirement to treat a more considerable quantity of sewage water, different combinations of the equipment can be effected. Maximum combination of 3 x UH-1,5 models (max. total capacity of up to 4.5 m3/day)

Within the framework of complex service, we deliver a corresponding plastic septic tank. It is delivered without a cover because of the possibility of having it located in different depths. To cover the tank, it is possible to use concrete ceiling panels. Effective cubic volume is 4 ; 6 ; 8 m3. Upon request and after prior consultation, we can also deliver a non-standard version.

Note: STP may be installed in any kind of leak-proof reservoirs (cesspool, septic tank)!
The equipment is totally self-enclosed, and works in an aerobic level of purification, so that it does not produce any disagreeable odours. Assuming that the sewer intake will be ventilated above the level of the top floor of the building, it will be sufficient to have a 1 m wide protective band between the sewage treatment plant and the surrounding residential buildings. The actual effect of the sewage treatment plant is increased by the effect of the mechanical equipment placed in front of it (cesspool, septic tank). It can reach up to 30% BSK5 and 50% NL.

According to performed analyses, the decrease in the bacteria content is very significant to the sewage treatment plant, and reaches:

Advantages of the sewage treatment plant.

* possible installation for any type of wastewater sump
* preventive environmental protection = cleaned water of high quality
* possible utilisation of cleaned water for watering
* low operating costs
* simplicity of the equipment and operation – unit principle
* operation reliability

Suggested treatment technology.

The HERVA STPs are to be used as secondary treatment plants. These plants may be used only for cleaning domestic wastewater. The units have the daily capacity from 500 litres (approx. 110 UK gallons) up to 4.500 litres (approx. 990 UK gallons), depending on the type of treated household wastewater. This volume corresponds to a household of about twelve people. The STP works on the principle of rotating bio-disks in a tank which has a sedimentation section on its bottom. Prior to the actual treatment process, a mechanical pre-treatment process takes place, either in a settling pit or a septic tank.

The sludge, generated by the treatment process, may be disposed of during maintenance.

Description of the sewage treatment plants’ functions.

Mechanically treated wastewater is drawn out of the septic tank with a transportation mechanism into the biozone which contains slowly rotating bio-disks. The actual treatment process is provided by a biomass of micro-organisms.

Some of them build a film on the bio-disks while others float freely in the biozone. The energy necessary for the biomass to work is gained from the wastewater. The oxygen necessary for the biomass to “breathe” is generated by the rotation of the bio-disks.

The wastewater is subsequently released, through an overflow, from biozone 1 to biozone 2, in which the wastewater flows constantly over a rotating drum-disk for further oxidisation in synchronisation with
the bio-disks. This provides intensive aeration, aerobic stabilisation, and additional treatment of wastewater.

The sludge, which is formed mainly in the biomass, is separated from the wastewater in the sedimentation section, which is a conical-shaped space in the lower part of the tank. The sludge is regularly and automatically removed from this space by a programmed sludge pump at certain intervals.

The treated wastewater is released from the treatment tank through a tilted overflow opposite the wastewater influx. The treated water may be then released into the ground or use for watering or garden irrigation (if allowed by the local legislation).

Utilisation of sewage treatment plants.

Sewage treatment plants are used as the second step of cleaning placed beyond the adjusted cesspool or a septic tank. There it is possible to clean only wastewater and water of similar kinds. The plants may not be used to clean industrial water, water from healthcare facilities, and water containing oil products. No wastewater containing any harmful substances may enter the plants (larger amounts of disinfection agents, acid or alkaline substances) of any concentration. Water from restaurants, guesthouses, etc. must be rid of fat and grease in the efficient grease catcher prior to entering a septic tank.

Installation.

The STP must be placed on a horizontal platform (optimally made of concrete) provided with a hole measuring of 500 x 500 mm, for the STP’s scooping mechanism, a feed cable and a passage for the hose (e.g. a heavy duty plastic pipe set into cement) for summer operation, if applicable. After the installation of the STP, part of the opening will be covered with a tin sheet. There is not limit on the width or the height of the platform. Generally it is about 10 cm high, made of gravel sand cement or crude brick work.

Installation over a septic tank.
The STP is to be installed over biozone 2 ("the last compartment") of the septic tank.

Installation over a wastewater sump (cesspool).

In order to meet the condition stating that a STP should be used only as a second-step purification method, i.e. after a mechanical pre-purification process, we recommend to put a partition in the wastewater sump as to a separator, trap, allow to putrefy, and thereby sanitate insolvable particles in wastewater. Optimally, the partition should divide the sump at a ratio of 2:1, but no less than 1:1. The partition must be at least 1,300 cm high; ideally, it should reach the upper edge of the feeding drain and feature 3 elbows of at least 150 mm in diameter, where their lower edge should be about halfway between the bottom of the tank and the feeding drain, but no less than 600 mm high. This triple-elbow

device in the wastewater sump prevents the sludge from overflowing from the first part of the tank to the other. Between the upper edge of the partition and the top of the sump, there must be a space of at least 300 mm.
In case the STP has to be installed over a sump where the placement of a partition would be extremely difficult of impossible, the STP must be emptied and cleaned more frequently.
In such a case, we recommend to place the scooping mechanism opposite the feeding drain or to install a filter basket (not included in the price).

Minimum sump lid load (cesspool, septic tank) where the sewage treatment plant is to be installed must be constructed in respect of the plant’s load in full operation (filled with water, service operations) of the total weight of the plant / lid load, i.e. UH-0,5 model 780 kg / from 8000 N, UH-1 model 880kg / from 9000 N, and the UH-1,5 model 990 kg / from 10000 N. This applies to shallow placing of the sump. In case of deep placing, it is necessary to consult this with the entity involved in the construction of the sump or its installation based on the total amount of filled soil.
Before the installation of the HERVA sewage treatment plant itself, it is always absolutely necessary to secure the discharge of the sump (cesspool, septic tank) up to approx. 1/3 of the total depth.

Summer and winter operation.

During the operation of the STP in summer, if the septic tank or the existing sump is shallow (i.e. with its upper edge almost on the same level as the ground), the existing drain should be provided by a hose into a concrete rim. With deep-set septic tanks/sumps, a brick wall has to be built around the well upward from the ceiling of the tank/sump in order to install the scooping mechanism (over biozone 2) and the sludge drain (under biozone 1).
The brick-walled well is then filled out with earth up to ground level. In this case, the draining of purified water can be effected through an underground frost-proof pipe, provided the above conditions are satisfied.
In existing septic tanks, the drainage uses the existing opening.

During the operation in winter, the width of the hose should range from 1" to 5/4". It should be attached to the drain situated underground in the frost-proof depth in the wall of the septic tank/sump. Suitable material for the drain is, for example, ceramic clay, cast iron or heavy-duty plastic. The inner diameter of the pipe should not be less than 100 mm: optimally 150 to 200 mm. Where the purified water is allowed to seep into the ground, the drain pipe must be long enough to ensure the necessary capacity required for winter operation. If the ground is clayey, the drain passage should be filled with gravel sand (and complemented with a soak-away) for greater capacity. This type of drainage or winter filtering requires adherence to the respective norms.
Hoses for summer and winter operation may be left in place, because if the summer hose happens to freeze up, the water is drained automatically through the winter hose/pipe - and vice versa.
It is recommended to attach one 1" extension to the 5/4" drain opening to enable the attachment of a hose.

Electrical energy input.

Power engine - Siemens electrical single-phase motor, type 1LF7060 - 120W (or equivalent) uses 230 V current. Motor and the heating elements have their own switch, encased in a waterproof box. STP’s are also equipped with a meter of “hours of operation” in order to check if the particular STP works continuously.
For standard models, a 3 x 1 mm2 to 3 x 1.5 mm2 CYKY conductor is used; automatic models require a 5 x 1 mm2 to 5 x 1.5 mm2 CYKY conductor. The circuit is secured by an independent circuit breaker.
It is recommended to provide the front-end protection using a circuit-breaker with a C2 earth-leakage circuit-breaker (with standard version), or B6 (with automatic de-slurring version) 230V, Iv 0.03 mA
Power supply for the sewage treatment plant is to be provided is accordance with a corresponding norm and it will be checked before putting into operation.

A custom-made version – a plant with a thermostat securing the automatic switch-on of the heating system when the temperature drops in winter to secure optimum function of cleaning

Basic conditions for installation:
* opening measuring of 500 x 500 mm (or 600 x 600 mm)
* air ventilation system of the reservoir (cesspool, septic tank) above the roof of the building (house)
* electric current supply through the base under the plant – independent protection in the distribution box

Additional conditions.

Maintenance of the STP consists mainly of frequent checking of the operation and regular draining of the sludge through the opening in the front wall of the tank. It is recommended to clean the entire unit at least once a year.
Detailed directions concerning the operation and maintenance of the STP are contained in the Operating Manual.

When stabilized, the sludge can be taken to compost or used for supplementary fertilization. In septic tank installations (if they are large enough), it is possible to reverse the operation by draining sludge back into biozone 1. If this is done, it becomes necessary to empty and clean biozone 1 regularly about once or twice a year. The purified water may be drained into a surface water stream or into the sewage system or it can be used for fertilization or garden watering.

When ordering or before installing the STP, we require the information on the depth of the hole intended for the STP.

Guaranty: 24 months from putting into operation; maximum 27 months from taking over the sewage treatment plant and putting it into operation.