Bio permaculture 04a.11c: Pond as a purification plant - plant purification plant WITHOUT Chemicals

The biological purification pant: gravel, sand, and reeds make it possible - and in flatlands, a small water pump

   
Pond with reed pond (biological wastewater treatment plant) above [1] - Pond purification plant with purification plants working [4]

by Michael Palomino (2020 - translation 2025)

4a11c. Pond as a treatment plant - the natural purification plant with plants WITHOUT chemicals

Ponds with reeds filtering gray water - the biological treatment plant
-- Ponds can serve as biological purification plants by planting reeds: The reed bed filtering system recycles gray water [web01]
-- Reeds feed on nitrogen and purify the waters together with microorganisms: The reeds consume many nutrients, and microorganisms inhabit the reeds. These organisms release antibacterial substances into the water and thus clean the water when it's contaminated with wastewater [web10]
-- With a pre-treatment stage and a decomposition basin full of gravel, sand, and reeds, as well as a control basin, biological purification plants can be set up [web11].

Pond with reed pond (biological purification plant) above [1]

-- reed details (German): https://www.dehner.de/produkte/schilfrohr-X008313884/
-- Book "Tricks with Mother Earth" chapter 14: biological purification plant
http://www.soz-etc.com/natur/Ldw-perma/Dt/BUCH-tricks-m-Mutter-Erde-in-Ldw-2019-version03-2okt2019.pdf
 

Details:

A natural purification plant system cleans wastewater in 2 stages:

1) At the entrance to the first basin, a mechanical filtration is installed with a filter.

2) In the second basin, the wastewater is biologically cleaned with reeds [web02].

The reeds consume many nutrients, and microorganisms populate the reeds. These organisms release antibacterial substances into the water, and in this way, they are cleaning the wastewater [web03].

Natural wastewater treatment plant in the plain and on the slope with the reed of the natural purification plant - diagram [2]

The natural plant treatment system

A purification system with plants consists of

1) a reservoir with incoming wastewater, with a screen against large objects in front of it

2) a decomposition basin: with gravel, sand, and reeds (e.g. Phragmites australis)

3) and at the end, there is a control well installed as an outlet, the treated water is monitored with measurements [web01].

The central basin, where the degradation processes are taking place, can naturally reduce most wastewater components. Here are combined the effects of

-- filters (mechanical process)

-- bacteria: absorbing or reducing the wastewater components (biological process)

-- organic processes: wastewater components are taken up or reduced (biological process)

-- the soil: absorbs the wastewater components (physical process)

-- between the roots: precipitation of substances occurs (chemical process) [web01].

The degradation processes mainly involve

-- the reduction of carbon

-- nitrification [web01].


Natural treatment plants are oriented vertically or horizontally

There are purification plant systems with plants:

-- vertical: The wastewater flows automatically from top to bottom (with optimal results) with a high nitrification rate, but less denitrification.

-- horizontal: The wastewater flows with mechanical pumps from the entrance to the exit with a low nitrification rate, but more denitrification.

They are like wetlands and can cause a mosquito horror [web01].

Conditions for a natural plant treatment system: Pumps and some electricity

-- The nitrogen cycle must be controlled by the pH level and water temperature

-- Natural plant treatment systems do not freeze in winter, but continue to operate

-- Natural plant treatment systems only require a few pumps; other machines are NOT necessary

-- Overall, the maintenance of a natural treatment system is not costing much

-- The bacteria involved in the decomposition process are found in the soil and do not rely on a 'living sludge' that needs to be added

-- This means that a natural plant treatment system works in almost any environment in the world [with some pumps and some electricity] [web01].

The purification plants for a plant purification system

Plants with purifying properties are:
-- Reed
-- many others, you have to ask the gardeners and pond builders.

The center is the purification pit with pebbles, sand, and reed – or just with the roots

  
Pond sewage purification plant under construction [3] - Pond sewage purification plant with sewage treatment plants working [4]

Normally, a natural constructed wetland consists of 3 basins. The center of the natural constructed wetland is the second basin with gravel, sand and plants (reeds) [web01].

There exist also sewage treatment plants with only one long basin into which the wastewater enters from one side and the purified water comes out at the end of the basin [web01].


Variations of the pit (the central basin)

Variant 1) with faecal sludge

In a central basin of a natural constructed wetland

-- substances heavier than water are settling and are forming the faecal sludge (faecal sludge, silt faeces)

-- there are substances floating on the surface which are lighter than water

-- In some cases there are almost no faeces and there is almost no faecal sludge (silt faeces) [web01].

Usually, the pool is filled with faecal sludge within a year and should be removed once a year. But there are also cases of natural sewage purification plants in which faecal sludge is degraded by biological processes in the reservoir itself and almost nothing accumulates [web01].

Variant 2) with wood chips - and a compost dough is created

A dry filter basin with two compartments will be installed:

-- The floor is a felt

-- On this felt, a thick gravel layer is put

-- Into this thick gravel layer, a layer of wood chips from deciduous trees is installed (conifers are not possible because of their antibiotic effect) [web01].

The faeces are deposited in the wood chip filter and in the gravel, but at the same time remain in contact with air. There is no rot or stench. When the first basin is full, the second is used. The end product is compost mass [web01].

Variant 3) with composting toilet with separate urine

When the natural sewage treatment plant is connected only to composting toilets with separate urine, there will be no stool deposition in a central reservoir. The natural sewage treatment plant needs only half of the area [web01].

Variant 4) without soil layer, only with plant roots

It is possible to install a natural sewage treatment plant without a layer of faeces, without a layer of gravel or wood, simply with plants that stand on their own roots. Most of the cleaning work is done by the plants and the microorganisms in the roots. In this way there is a stronger flooding and weight can be saved, so that the installation is also possible on roofs [web01].


The processes in the basin

-- There are no bad smells: In principle, everything is always in motion and therefore no bad smells emanate from natural constructed wetlands

-- Plants are absorbing: Plants are growing absorbing a part of the wastewater components

-- The roots of the reeds: The roots of the reeds keep the soil permeable for oxygen etc. – compaction caused by stepping on it is compensated for, or there is a balancing effect on the formation of new faecal layers

-- Microorganisms and soil bacteria are cleaning: Microorganisms and soil bacteria are purifying a large part of the wastewater by chemical reactions [web01].

-- Gravel binds phosphates [web02].

1) Plant roots are enriching the soil area with oxygen: Many swamp and aquatic plants are transporting oxygen to their roots and then they are distributing it in the soil water at depth (oxygen-rich zone, aerobic zone). In this way, autotrophic microorganisms can work on the first step of purification: nitrification [web01].

2) Oxygen in chemical compounds: There is a case when oxygen can be found in chemical compounds only (oxygen-poor zone, anoxic zone), e.g. in nitrate, the product of nitrification. Heterotrophic microorganisms that have a carbon source, are working with this nitrate and therefore nitrogen comes out as a gas. This is denitrification [web01].

3) Cleaning in oxygen-free zones (anaerobic zones): There is an unpleasant smell of rot, which only occurs in special cases such as anaerobic cleaning [web01].


The decomposition processes: cycles

The majority of wastewater consists of nitrogen compounds. The processes of decomposition relate to

-- the nitrogen cycle

-- the phosphorus cycle

-- the sulphur cycle

-- the ammonia cycle (ammoniation) [web01].

The main processes are denitrification, ammonia processing and ammonia oxidation. This process of ammonia ("anammox") is especially important when little chemical oxygen is required [web01].

Particles decompose and accumulate as microbial biomass through a metabolism. This leads to ammonia due to microbial biomass or plant residues. Mineralization occurs by conversion to inorganic nitrogen [web01].

Atmospheric nitrogen is water-soluble in small quantities and is an element of the system [web01].


Other nitrogen decomposition processes

-- with precipitation (nitrogen enrichment)

-- with ion exchange (nitrogen enrichment in clay minerals)

-- with degradation processes (nitrogen enrichment in remains of dead plants as a supplement to the incomplete microbial ammonification of plant remains) [web01].

Precipitation of phosphate: The natural pelvic floor contains iron salts or other minerals which combine with phosphate forming an insoluble compound which falls to the bottom (precipitation) [web01].


Side effects of a natural wastewater treatment plant: phosphorus

-- phosphorus may occur in the settling layer

-- when this plant biomass is removed, the phosophor is also removed

-- when the plant biomass is always eliminated the plants will absorb phosphorus as a nutrient and in this way it is partly eliminated from the wastewater

-- all in all the phosphorus does not react like a gas and remains [web01].


The last pool with the final inspection

The purified water ends up in a control well with measurements [web01], with tests on the purified water [web02], and

-- Nitrogen is measured

-- Phosphorus is measured

-- Carbon is measured [web01].

Reaction control is applied to carbon

-- how long a biological reaction of microorganisms takes

-- how long a chemical conversion takes etc. [web01].

In contaminated regions there may remain a contamination of ingredients which cannot be broken down by plants [web01]. At the end

-- the purified water enters the waters of the region, or

-- the purified water seeps into the ground, or

-- the purified water is stored for reuse [web01]

     - for watering the garden [web02].

Or a partial backflow can be installed with the purified water:


Reflux of part of the purified water

Natural constructed wetland in the plain and on the slope with the sewage treatment plant reed - scheme [2]

For maximum water quality: a certain part of the purified water flows back into the inlet

When maximum water quality is needed

-- in a sensitive area

-- in an area with an ecological groundwater reserve

-- in case of a water discharge into a swimming pool

-- in the production of process water

-- with stricter ecological limits due to the customer's conditions [web02]

some of the water - which is leaving the wastewater treatment plant - is returned to the entrance:

-- to dilute the incoming wastewater

-- to prevent the formation of sulfur odor (hydrogen sulfide)

-- to prevent the formation of faecal sludge (faecal sludge)

-- to "vitalize" the wastewater already in the first phase

-- to improve all stages of the decomposition process [web01].

In the case of vertical natural wastewater treatment plants that allow purified water to flow back, a pump is required.

In horizontal natural sewage treatment plants, the return of purified water is carried out by gravity [web01].

It's possible to add a pond [web02].

Pond with reed pond (biological treatment plant) above [1]

Or one can install a swimming pond with a small, natural treatment plant with reeds:

Swimming pool with purification plant reed [5]

<<           >>

Sources
[web01] https://de.wikipedia.org/wiki/Pflanzenkläranlage
[web02] https://naturbauhof.de/lad_pka_funktion.php
[web03] https://www.dehner.de/produkte/schilfrohr-X008313884/


Photo sources
[1] Teich mit Schilfteich nebendran: https://naturbauhof.de/lad_pka_funktion.php
[2] Schilfteich als Kläranlage, Pflanzenkläranlage in der Ebene oder am Hang: https://naturbauhof.de/lad_pka_funktion.php
[3] Teichkläranlage im Bau: https://www.aquant.de
[4] Teichkläranlage fertig am Laufen: https://www.aquant.de
[5] Swimming Pool mit Klärpflanze Schilf: https://www.aquant.de

^