Reed Bed Reading Answers: IELTS Reading Practice Test

Reed Bed Reading Passage

Paragraph A: 

Recent studies have shown that plants—or more precisely, roots—play a critical role in cleaning up contaminated water before it enters seas and rivers. In the 15th century, wetlands in Britain were used to clean contaminated water. People started to understand the effectiveness of the "natural" method of purifying water. Subsurface flow wetlands (SSFW) are now a popular alternative for treating wastewater in rural areas in Europe. The number and size of these systems in use have primarily increased over the past 10 to 12 years. Rural areas should not use the traditional water purification method that is used in large cities where there is a lot of water that needs to be cleaned.

Paragraph B: 

The common reed can move oxygen from its leaves through its stem and rhizomes and out through its roots. As a result of this action, the root system's aerobic, anoxic, and anaerobic zones develop a very high population of microorganisms. This fluid can be effectively treated because the wastewater moves very slowly through the mass of reed roots. They are frequently so effective because a variety of pollutants are degraded or removed by natural biological, physical, and chemical processes that interact with one another in the root sector of the bed.

Paragraph C: 

Water can be purified horizontally or downwardly using artificial reed beds. When a thick layer of root hair has developed, the reeds continue to flourish the best. The roots take three years to mature fully. Depending on the country in Europe and its primary development lines, a particular country may apply different wetlands. In addition to developing wetlands with the horizontal or vertical flow for wastewater treatment, Europe has had great success using wetlands for sludge treatment. A few special design options allow for the treatment of diffuse pollution, the treatment of some types of industrial wastewater, the treatment of agricultural wastewater, and the retention of microbiological organisms in constructed wetlands.

Paragraph D: 

A horizontal system is employed if the water is only mildly polluted. There are two types of horizontal-flow wetlands: free-water surface flow (FWF) and sub-surface water flow (SSF). The effluent in the former freely flows above the sand or gravel bed where the reeds and other plants are planted, whereas the effluent in the latter passes through the sand or gravel bed. Effluent is treated by plant stems, leaves, and rhizomes in wetlands of the FWF type. These densely planted FWF wetlands typically have water depths of less than 0.4 meters. Dense vegetation, however, can restrict oxygen's ability to diffuse into the water.

Paragraph E: 

These systems are essential for tertiary treatment and the polishing of effluents, and they perform especially well for low-strength effluents or effluents that have undergone some types of pretreatment. The liquid slowly flows horizontally through a long bed of reeds in the horizontal reed flow system. The reed bed is about 100 meters long. The disadvantage of horizontal reed beds is that they take a long time to produce clean water and take up a lot of land.

Paragraph F:

 
Reeds are grown inside of a vertical flow (downflow) reed bed, which consists of a sealed trench filled with gravel and planted with reeds. In a downflow system, a bed 60 cm deep is where the reeds are planted. In vertical flow reed beds, the wastewater is applied at the top, then flows through a rhizome zone with sludge as a substrate, through a root zone with sand as a substrate, followed by a layer of gravel for drainage, and is collected in an under drainage system of large stones.

Paragraph G: 

Millions of bacteria, algae, fungi, and other microorganisms that digest waste, including sewage, clean the effluent by slowly percolating it through the various layers of the bed's surface and into an outlet pipe that leads to a horizontal flow bed. There shouldn't be any bad odours because there is no standing water.

Paragraph H: 

Systems with vertical flow reed beds are significantly more efficient than those with horizontal flow reed beds at lowering levels of biochemical oxygen demand (BOD), suspended solids (SS), and ammonia as well as odours. They are capable of handling much stronger effluents that contain heavily polluted materials and have a longer lifetime value. They are typically considerably smaller than horizontal flow beds. A vertical reed bed system operates more effectively than a horizontal reed bed system, but it also requires more management and requires multiple beds and a distribution system because its reed beds are frequently operated for a few days before resting.

Paragraph I: 

The natural method of purifying water has many benefits over the traditional method. Less money is needed for installation, operation, and maintenance when using nature. Additionally, it has a pleasing appearance and can enhance the natural environment. Reed beds are natural habitats that can be found in estuaries, swampy depressions, and floodplains. The biologically proven, environmentally friendly, and visually non-intrusive natural bed systems for treating wastewater also frequently outperform mechanical wastewater treatment systems. In most cases, reed bed systems are more affordable to install over the medium to long term than any other wastewater treatment. They naturally protect groundwater, dams, creeks, rivers, and estuaries and are environmentally sound.