How to Choose the Right Wastewater Treatment System for Your Home: Non-Collective Solutions Compared

How to Choose the Right Wastewater Treatment System for Your Home: Non-Collective Solutions Compared

Posted on 03 Jun 2022 by Lise Helluy

If you are looking for an environmentally friendly and affordable way to treat your wastewater, non-collective sanitation devices may be the right choice for you. There are a variety of treatment devices available on the market, each with its own advantages and disadvantages. In this blog post, we will discuss the different types of non-collective wastewater treatment devices and how to choose the right one for your home. 

What is non-collective sanitation?

BIOROCK sewage systemSo, first, what exactly is wastewater? It is the combination of black water (toilet wastewater) and greywater (washers, sinks, cooking, and bathroom showers). The sanitation systems must be engineered to accommodate the treatment of all of these wastewaters. A sewage system may be put in place during building or renovation. Each dwelling not connected to the sewerage system must have its own wastewater treatment system.

Non-collective sanitation is a type of wastewater treatment that does not require a central sewage system. Instead, each individual home or business has its own treatment system. There are many advantages to non-collective sanitation, including lower costs, less infrastructure, and less environmental impact. Non-collective sanitation is also easier to maintain than a central sewage system.

If your existing sanitation solution has been found to be defective by the local authority (or SPANC) after a control visit, you are required to upgrade it.

There are two main types of non-collective sanitation devices: compact filters and soil-based treatment systems. Compact filters are small devices that can be installed close to your home or business. They use bacteria to break down pollutants in the water. Soil-based treatment systems are larger devices that are installed outside your home or business. They use plants and soil to filter pollutants from the water.

How to make a choice between all the sanitation devices? 

There are many factors to consider when choosing a non-collective wastewater treatment device. The first step is to determine your needs and preferences. Do you need a compact device that can be installed close to your home or business? Or do you prefer a larger soil-based system that is more voluminous? Once you have determined your needs, you can begin to compare the different devices on the market. Consider the following factors:

  • How it works: Each type of non-collective wastewater treatment device works differently. Some use bacteria to break down pollutants, while others use plants and soil to filter pollutants from the water. Choose a device that uses a treatment method that you are comfortable with.
  • Conditions: Each type of non-collective wastewater treatment device has different conditions that must be met in order for it to work properly. Make sure the conditions required by the device you choose are feasible for your home or business.
  • Characteristics: Each type of non-collective wastewater treatment device has different characteristics. Some devices are more compact than others, while some devices require less maintenance than others. Choose a device that has the characteristics that you are looking for.
  • Advantages and disadvantages: Each type of non-collective wastewater treatment device has its own advantages and disadvantages. Be sure to weigh the pros and cons of each device before making your final decision.
  1. Approved treatment devices: Approved treatment systems are made up of all the sanitation solutions approved by the ministries in charge of health and ecology. The approvals obtained relate to the treatment of exclusively domestic wastewater.

COMPACT FILTERS: (Like BIOROCK Wastewater Treatment Plants)

BIOROCK installationHow does it work? The primary treatment is provided by a primary tank that collects all the greywater from the house. Then, the secondary treatment is carried out within a filter bed. This filter bed can be made of different materials: zeolite, coconut shavings, rock wool, and sand... on which the purifying bacteria are fixed. They use bacteria to break down pollutants in the water. Finally, the treated water is infiltrated into the ground or discharged into the ditch depending on the case. These devices have visible ventilation stacks on the ground.

  • Advantages: Low cost, easy to install, low maintenance, approved for secondary residences, no electricity consumption: except if a lifting system is installed.
  • Disadvantages: Requires effective secondary ventilation, and expensive filter change every 8 to 15 years.


PLANTED REED FILTERS: The main treatment is done by a primary tank, which collects all of the house's wastewater. The Phyto-purification approach is used in the reed filter.

planted reedHow does it work? The roots of these reeds are particularly well developed, allowing them to drain mineral nourishment, bring oxygen, and serve as support for aerobic bacteria. The plant roots are the source of organic nitrogen for terrestrial plants. It is essential to understand how bacteria can break down and mineralize organic waste (sludge). This sludge will be accessible to the plants. Once a year, in autumn, it is necessary to proceed to the mowing i.e. to cut the vegetative part of the reeds. This operation will bring oxygen to the pond to better filter the wastewater. 

  • Advantages: Excellent purification performance, no sludge production, and no odor release. It is also well-integrated into the landscape.
  • Disadvantages: Maintaining the lawn, trimming it, and mowing it is a time-consuming process. It requires annual maintenance and mowing.


How does it work? A primary decanter, also known as a primary tank, is the first step in treating wastewater. The bacteria present in the biological reactor, which receives oxygen, handle the secondary treatment. These bacteria are fixed on support (mineral, plastic, ...). The treated wastewater is then passed through a clarifier and reintroduced to the primary clarifier, where it is stored. The treated wastewater is discharged by permeation into the soil, irrigation of plants, or discharge into a ditch or a river (if the regulations in place in the country allow it). When the sludge reaches 30% of the plant's volume, it must be emptied.

  • Advantages: Old and mastered technique, many suppliers, compact devices, can be installed in protected areas
  • Disadvantages: Higher electrical power usage (compressors are on all of the time), requires secondary ventilation on the roof of the house to avoid bad odors, and can only be utilized in primary residences.

FREE CULTURED MICRO PURIFICATION STATIONS: the Microstation with free cultures is a compact and complete device that allows treating your wastewater in an effective way. 

How does it work? There are 2 main families of free cultures: The "free culture" which works on the same principle as the treatment plants of the big cities. The "SBR" technique "Sequencing Batch Reactor", is a version of the free culture micro-stations where the biological reaction and the clarification phase take place in the same compartment. This technique allows a lesser production of bad odors than the fixed culture systems or with a primary tank, without being as efficient as the free-culture systems.

  • Advantages: Technology from the collective stations of the big cities: (guarantee of quality and good functioning of the device), No secondary ventilation (for some models), Low electrical consumption, Low ammonia discharge (allows a discharge in a ditch, a stream or a pond).
  • Disadvantages: Products not well known by the prescribers (not necessarily recommended by all design offices), cannot be installed in secondary residences


2. Soil-based treatment systems: Soil-based treatment systems are larger devices that are installed outside your home or business. They use plants and soil to filter pollutants from the water. These systems consist of a septic tank (also called "Primary Tank" at the entrance) and a treatment and infiltration system in the soil.

SPREADING TRENCHES: This tool is one of the most utilized in non-collective sanitation, but there are two requirements: the ground must be porous enough, and the accessible surface must be quite significant (between 150 and 200 m²). 

How does it work? The soil in place treats the wastewater and removes it. The sewage is then dispersed in several trenches at a shallow depth. Under normal circumstances, 15 linear meters per person are required.

  • Advantages: cheapest device on the market for autonomous sanitation.
  • Disadvantages: consumes a lot of space, quite strict implementation. 

SAND FILTER: There are two distinct kinds of vertical sand filters: drained and non-drained. A network of pipes takes the treated water from a drained sand filter and releases it into a ditch, for example. The untreated water from the non-drained filter will seep deep into the earth.

How does it work? The primary tank retains the wastewater from the house. The wastewater is filtered in a sand filter at the end of its treatment process. The microorganisms attached to the sand purify the water. The wastewater is first processed in the gravel portion, after which it's completed in the sand part.

  • Advantages: Consumes less space than trenches
  • Disadvantages: The tarp is complicated to implement owing to the danger of perforation (and therefore non-compliance), More expensive than trench systems, and no plant, road, or structure may be built above the filter. 


wetlandsIt's the only one in this class that may be put into wetlands, and it works even if the soil isn't suitable for dissemination. It requires a surface of 60 to 120 m². It's a type of sand filter that is built above the ground and not inside an excavation. It works similarly to a vertical sand filter, but it is located above ground rather than below it. Infiltration mounds may be partially or entirely above ground. It is common to find an infiltration mound at the bottom of the garden, which will be a sandy bed that is higher than the surrounding plants. In practical terms, you'll have a "mound of dirt" in your garden.

How does it work? A lifting station will be used to direct wastewater from the primary tank to the infiltration mound. The wastewater to be treated will then be dispersed throughout the mound using spreading pipes. The treated sewage is then passed from layer to layer, beginning with the coarsest gravel layer and ending with the finest sand layer. These layers are put in place from top to bottom. The cleaned wastewater is discharged into nature at the bottom of the mound.

  • Advantages: If the requirements are met, it can be placed in a marshy area.
  • Disadvantages: Unsightly (loss of real estate value if the house is resold), Costly to install, Delicate aging (rodents, ...), and requires a large floor space. 

There are many different non-collective wastewater treatment systems to choose from, and the right one for you will depend on your specific needs and circumstances. Septic tanks, compact filters, free cultured micro purification stations, fixed cultured micro purification stations, soil-based treatment systems, and infiltration mounds are all viable options, each with its own advantages and disadvantages. Carefully consider all of your options before making a decision. This is why it is very important to call upon the local authority and the research department which will study your soil and your house in order to propose to you all the feasible sewage solutions to treat wastewater from your home. 

Find out in less than a minute which BIOROCK system is the most adapted to your project: HERE 


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