First of all a warning - if you have a new treatment plant under warranty, it's a good idea to follow the recommendations of the manufacturer or supplier.
check everything
The activation treatment plant needs to have functional technology, especially the supply of oxygen (air) and the activation and functional recycling of returnable sludge. Microorganisms are key to a biological treatment plant. Without them, the treatment plant will not work. But let's start from the beginning.
According to the manufacturer's documentation, you have prepared the space for the wastewater treatment plant, perhaps the manufacturer installed it for you. Even before setting up the treatment plant, it is good to remember that it will be necessary to have access to it, it will be necessary to bring electricity to it, or even air supply from a blower located somewhere else is sufficient. It is also good to be able to simply extend the hose for rinsing the treatment plant.
pour water
If the treatment plant is installed, it is very advisable to fill it with water, ideally clean, as soon as possible and test everything. If you do not fill it with water and gradually fill it with sewage, there is a risk that the groundwater will lift or deform it.
supply microorganisms
If the treatment plant is connected and adjusted, it is necessary to ensure a sufficient amount of activated sludge, i.e. microorganisms, for its proper functioning. There are basically two approaches. Either you leave it to nature and create the sludge yourself, or you vaccinate the treatment plant. The first option cannot be highly recommended. It is characterized by a relatively long period (on the order of months) when there is not enough sludge in the treatment plant, or when the sludge is overloaded. This is manifested by foaming and odor. After washing clothes or washing dishes, there is a risk that there will be so much foam that it will run away from the WWTP.
The second option consists in bringing sludge from a functioning wastewater treatment plant, for example from a nearby municipal wastewater treatment plant, or from a neighbor with a functioning wastewater treatment plant who will be happy to remove the sludge. After the inoculation of the sludge, a certain phase of adaptation will still take place, when the qualitative composition of the culture of microorganisms will gradually change, however, this phase does not have to be externally manifested in any way. The key question will be how much sludge to bring. For a treatment plant for 4-6 EO, it is advisable to inoculate at least 100 l of thickened sludge (2%) from the city treatment plant. That's the bare minimum. It is more appropriate to fill 1/3 of the activation volume with sludge from a well-functioning treatment plant, which has a sediment of 300-600 ml/l. This should achieve a state where, after inoculation, the sludge volume will be approx. 100-150 ml/l, which can be considered as the lower limit, when the sludge should already be so-called "caught". The ideal solution is to raise the entire treatment plant with the sludge from the mixed activation and achieve a straight sediment of approx. 300 ml/l. In this way, the treatment plant should work well almost immediately (but again, it is necessary to expect an adaptation phase of several weeks), but again the time will approach when it will be necessary to solve the treatment plant's sludge removal.
So what to recommend as the best – import thickened sludge from another functioning activation treatment plant until the sludge sediment in the treatment plant is at least 100 ml/l (better 150), after half an hour of sedimentation.
Footnote: there are manufacturers and sellers of various powdered bacteria, or enzymes, or various mixtures. Their influence is different, often on the border between a demonstrable effect and the uncertainty of its measurement. Some preparations can be effective, for example, on fats. We strongly do not recommend these preparations for inoculating a dry treatment plant. Activated sludge culture is much more complex, and the required amount of microorganisms to begin with is relatively large, otherwise they will be overloaded. Regardless of the financial side. But if you want to do "something extra", you believe in the product and are happy to pay extra for a good feeling, you will most likely not damage anything by applying the product.
feed them
If the treatment plant has functional technology, enough oxygen and microorganisms, it also needs to be fed. This is very important - if you have perfectly prepared the treatment plant for operation, but it does not have a supply of wastewater, the sludge will die again after a while. In an emergency, it is possible to solve this with some substitute organic substrate, for example sugar, flour, or even baked goods. Organic materials that also contain nutrients such as nitrogen and phosphorus are suitable, so that their deficiency does not affect microorganisms. On the contrary, substrates with fats, which dissolve poorly anyway, and also cause various operational problems.