Decorative pond for wastewater treatment

Water purified by our treatment facilities can be used by arranging a decorative biopond, which can serve as a reservoir for wastewater treatment, and can also be a decoration for your site. We will consider the features of artificial decorative ponds and what affects their appearance later.

Recently, it is not often, but you can still see artificial decorative ponds. Such reservoirs require constant water circulation and its purification in special filter blocks. These measures are necessary to maintain an unstable ecosystem within. Otherwise, the reservoir quickly turns into a muddy swamp with an unpleasant odor. Let’s consider some aspects of such an ecosystem.

Plants and the Sun

UV radiation, interacting with the chlorophyll of green plants, triggers the photosynthesis reaction, thanks to which plants synthesize complex organic substances that are part of the organs and tissues that form them – sugars, amino acids, nucleotides, lipids, vitamins – from simple mineral substances of inanimate nature – water, air (nitrogen, oxygen, carbon dioxide), salts of nitrogen, phosphorus, chlorides, sulfates, iron and other trace elements contained in the soil and water, thanks to the vital activity of bacteria. These substances are the basis of the nutrition of fish and zooplankton.

Bacteria and blue-green algae

Bacteria are the most numerous and diverse group of organisms that inhabit a water body. It makes no sense to list here all the varieties and types of their trophic cycles (food – synthesized substances – excretion products and by-products of vital activity). Let us dwell on the main function for the ecological system – bacteria destroy the corpses of large organisms that inhabit a water body (protozoa, worms, insects, fish, etc.) and the products of their vital activity, as well as dead parts of plants. Using them as food, they convert dead organic matter into simpler minerals that are soluble in water and available to plants, thus completing the ecological cycle.

Blue-green algae are more like bacteria than plants and are similar to plants only in that, like plants, they use ultraviolet light for biosynthesis. However, the structure of blue-green algae (single-celled prokaryotes that do not have a nucleus surrounded by a membrane) and the functions they perform (nitrogen fixation and decomposition of organic matter) are exclusively bacterial. For pond owners, they are “interesting” because they can turn a pond with clean water into a green swamp in a matter of days. By multiplying themselves, they provide rich food for other algae and phytoplankton, which also “support” them in terms of rapid reproduction. Therefore, the pond owner needs to have effective means of combating and counteracting the spontaneous growth of blue-green algae during the autumn and spring “blooming” of water.

Balance of the ecosystem.

The complex “relationships” between fish, bacteria, plants, phyto- and zooplankton (elements of the “pond” ecosystem) form complex trophic chains (who feeds on what or by whom and what remains after that). Understanding the need to maintain balance in an artificially created ecosystem is the basis for achieving the desired behavior of the pond, and therefore water transparency and fish growth. A swamp, in this light, should be considered as a special case of pond stability.

Despite the abundance and multifunctionality of bacteria, in a pond where fish are kept and bred in relatively larger quantities than in natural water bodies, the ecological balance is usually disturbed. There is an excess of nitrogen-containing compounds (ammonium nitrogen salts) and organic matter.

In addition, the relative deficiency of aquatic plants inevitably leads to the fact that excessive mineralization by silt bacteria, as well as the remains of humus depleted by plants, will accumulate at the bottom of the reservoir.

There are also external factors:

• 🔹 Dust and debris from outside.
• 🔹 Fish food residues
• 🔹 Algal spores and plant seeds
• 🔹 Daily temperature fluctuations that cause mud to mix with water

Thus, an artificial pond requires the following steps:

• ▻ Removing accumulated sludge and floating substances from the system
• ▻ Purifying pond water from phosphates, nitrogen-containing and organic substances
• ▻ Increasing the proportion of higher aquatic vegetation and arranging for the removal of excess sludge can to some extent increase the stability of the ecosystem.

Sewage instead of fish

The task of purifying water from phosphates, nitrogen-containing and organic substances that are difficult to oxidize is also faced during the secondary treatment of domestic wastewater, if they are not were chlorinated. Thus, a decorative pond, but without fish, can be used as a wastewater treatment unit. Moreover, such a pond will have a number of undeniable advantages over an artificial one.

The flow mode of the treated wastewater provides the following advantages:

• 🔹 No installation of pumping equipment for water circulation and filter unit is required
• 🔹 Complete absence of energy consumption
• 🔹 Year-round operation with minimal maintenance
• 🔹 The ecosystem becomes open and self-regulating, while in an artificial pond the ecosystem is closed (closed on itself) and difficult to balance
• 🔹 Possible way of wastewater utilization

Setting up a biopond

If the Wastewater Treatment Plant (WWTP) is far from the reservoir, we suggest directing the treated wastewater into an artificial biopond, the bottom of which is equipped with a special airtight canvas. Aquatic plants are planted in such a pond. The walls and banks of the pond are decorated with decorative stones and boulders.
Such a pond does not require a circulation and filtration system (since the system is not closed, the reservoir will not become waterlogged).
With a pond volume that ensures the presence of treated wastewater for 24-48 hours, the pond will not freeze even in winter.

The pond simultaneously performs the following functions:

• 🔸 Visual control of the quality of treatment.
• 🔸 Additional treatment function. Nitrogen and phosphorus (nitrogen-containing substances and phosphates) coming with treated wastewater are absorbed by plants as fertilizers, and the remaining organic substances that are difficult to oxidize are absorbed by hydrobionts and decompose under the influence of ultraviolet (sunlight).
• 🔸 Buffer (stock of clean water) in case of violation of the treatment regime. (The available volume of water in the pond can significantly slow down the growth of the concentration of pollutants in the water flowing out of it in the event of an accident at the Treatment Station). Moreover, in the event of a complete power outage (aeration of the main structures stops), the biopond will be able to maintain the purification of clarified water leaving the Treatment Station for several days. The purification effect will be at the level of 80% of the design one. In the future, the purification effect will slowly decrease to 60% for 10-15 days, an unpleasant odor may appear.
• 🔸 Aesthetic, decorative and educational function.
• 🔸 The function of psychological demarcation of wastewater and the source of household water supply.