There are several ways that have been developed to help with water quality improvement. The levels of water quality improvement vary depending on the type of system design used as well as modeling approaches applied. Good system design will help in water quality improvement through water treatment and other processes aimed at achieving safe water that can be used for human consumption. A system for water quality improvement involves several processes and series of steps aimed at reaching the purest water that can be used for human consumption. One of these systems that can best help in water quality improvement is the constructed wetland system design. This is an article review on how to apply modeling to improve water quality with reference to constructed wetland system design case study. (Gelt, 2007)
Literature review: Constructed wetlands system design
According to (Gelt, 2007) a constructed wetland is a water treatment facility designed to help water quality improvement. The system is designed in a quite complex way full of integration where there is the use of water, microorganism, soil, air, plants and animal interaction made to the improvement of water quality. These system designs are an artificial one and therefore the name “constructed wetlands.” There exists another type of wetlands that are natural and make use of geology structure, hydrology, and biology to come up with natural wetlands. The constructed wetlands are made purposely to help in the treatment of wastewater thus enhancing water quality. Wetlands are systems that are currently receiving worldwide attention for wastewater treatment and reclamation for quality water management. They are very cost effected and can be easily be operated as well as maintenance.
Constructed wetlands are designed to effectively do away with pollutants that are associated with municipal and industrial wastewater as well as stormwater. It’s a system designed in a way that it can improve the quality of water by removing present water contaminants like BOD, solids that are often suspended in water, nitrogen, phosphorous contents, hydrocarbons and metal particles that can be present in water. The wetland systems are further used in treating municipal effluent, industrial wastewater, animal waste present in running water, acid mine drainage and landfill leachates. The reliably on this method is beneficial since it’s not only limited to improving water quality but also serves other uses such as acting a wildlife habitat since it’s an attraction to several animals. Its, therefore, can be a tourist attraction site.
How wetland works
The functionality of any wetland is determined by the type of soil, the surface, and groundwater-surface movement. As explains, either artificial or constructed wetland serves a purpose of improving water quality among other benefits. (Ronca, 2017) The following are the ways in which wetland helps in water quality improvement.
During heavy rains, water is usually accumulated in large ditches that may be as a result of mining or related activities. They, therefore, act as water catchment areas. After accumulation of water in these areas, there is always a stream of water flowing through underground water movement which can end up being released into the watershed. Water in these gallons is not safe for human use, but when passed through the underground water flow, it undergoes some processes that remove some impurities thus improving the water quality level. The following processes take place:
Nutrient and sediment filtering
In areas that people practice intense agricultural practices, wetlands play a very important role in maintaining and improving water quality. Agricultural practices contaminate water from appliances of pesticides and other chemical applied during farming processes. Wetlands help in improving water quality in such regions through the removal of nitrogen components, phosphorus traces, and pesticides present in agricultural runoffs. Chemical and other nutrients enter any wetland in two different ways, either via the surface water or sediments or groundwater. Though these ways, it may collect some inorganic nutrients while entering the wetlands. Some of the nutrients commonly collected are nitrogen and phosphorous. The wetlands help in clearing away the nutrients from the surface water and are moved into the sediments, to the plants present in the wetlands and atmosphere. (Miller, 2009) Through subsurface drainage, nitrates are lost from uplands sites and are absorbed by plants and later converted into nitrogen gas which is lost to the atmosphere. Aquatic plants help as in efficiently removing the nitrate. (Sudarsan & Lizbeth Roy, 2013)
Another impurity that is removed from this surface water is Ammonium. Surface water contains traces of ammonium. Plants and aquatic life present in wetlands help in converting ammonia into nitrogen through a process of volatilization. Another process of nitrification helps in conversion if nitrates into nitrates which can easily be removed from surface water by the wetland plants than the ammonium form. (Kurzbaum & Armon, 2012)
Moreover, running water and open water carries along with its components and traces of phosphorus, some metals like the iron and aluminum together with organic nitrogen. These are attached to the sediment which is carried along by the surface runoff. The wetland helps in removing all these components thus purifying the water and improving its quality for safer usage. The wetland system does away with these components by allowing the sediments containing these impurities to settle on the bottom of the wetlands. Within the wetlands bottoms, present are roots of the aquatic plants that therefore remove the nutrients by absorbing them from the sediments. (Jacob, 2008)Most of the phosphorous and metal elements are from pesticides and herbicides chemicals used during farming activities. (Cooper, 2000) Water from this end is termed as of better quality since it’s been filtered and has fewer chemicals and harmful nutrients like phosphorous that are harmful for human consumption. Wetland idea is to filter sediments, and through a process like volatilization and nitrification, harmful gases and components are cleared away from the underground and surface water. (Parsons, 2001) It’s a system that uses several processes to reach to manage water quality improvement. By taking up and filtering nutrients during the summer period, wetlands can be effective ideas to design systems that help to decrease the possibility and chances if water contamination in downstream. The figure below shows the overall process and cycles as well as stages of wetland process in water quality improvement.
Designing a system from wetland idea
In most world regions, water is always a big challenge. Many people get water from rivers, lakes and other similar water sources. (Holland & Marjoe, 2002)This, therefore, exposes them to risks associated with using contaminated water. The idea of wetland can be used in combination with a water treatment system to come up with a method of improving water quality. The following Is an application using the idea of wetland method of removing impurities and later the water will be treated using water treatment method to get pure and safe water for human consumption thus improvement of water quality. (Taylor et al., 2000)
One can create a domestic or individual constructed wetland that can help water quality improvement and treatment. For a domestic wetland, we need;
- Septic tank- the size depends on the source of water and the amount of water needed
- Soil absorption field.
You can prepare a site where you intend to plant your wetland water treatment system and provide some temporary fence around the absorption field. This is meant to limit access by many people and animals as well as congestion. Clearing the surrounding bushes and any plantation is very necessary. You can add up soil in the area. The soil should be free from plants, debris, rocks and frozen clods. Grading and leveling the area is very necessary too.
Construction of wetland cell
The sizing of the wetland cell depends on the size of the family or the users of this water. For instance, a three bedroom home would require a larger wetland cell than a two bedroom family. According to (Taylor et al., 2000), two bedroom home will need a wetland cell of 300square feet with a dimension of 25 by 12 feet while a three bedroom family will require one with 30 by 15 feet. The sizing is done on the area between the inlet pipe and outlet pipe. When the process of excavation is complete, it’s important to level the bottom of the wetland. 3-6 inches in size can be put around the septic tank riser and any clean-outs and checking wells to shield them from incidental harm from vehicular activity. Ensure that surface water is occupied around and far from the wetland cell (figures seven and eight). One to two creeps of unbending protection on the sides of the wetland cell is prescribed for all of Indiana. The protection will help settle the wetland amid solidifying and defrosting cycles. (Watson & Steiner, 2003)
The requirements and size of the absorption field are determined by the factors that we can only know after some soil examination and testing. These factors include the soil capillarity level and the depth to reach the underground water. When constructing the absorption field, including 3-4 inch diameter monitoring wells in the trenches. These wells consist of PVC pipe with holes or slots located on the bottom 3-6 inches to allow water movement into the pipe. Place the pipe in the trench or bed before the addition of gravel. The bottoms of the monitoring wells are not capped. (Chescheir, 2008)
Use polyvinylchloride (PVC) and high-density polyethylene (HDPE), polypropylene or any other approved material to line the wetland bottom since they are impermeable. Other material coated with a material that is resistant to ultraviolet rays can be used. The wetland bed should be free from any opening and defect that may lead to leakage. Prior to setting the liner, it is a smart thought to fix the wetland removal with geotextile texture (four ounces for each square foot) or 2-3 inches of sand to shield the liner from punctures. It is imperative that the liner does not spill where the pipe enters and exits. You can fix the pipe both in the inlet and outlets to the wetland cell. Ensure you clean all the openings before cementing the pipes and the bottom of the wetland cell. You can conduct some testing on the operating pressure before burying the pipes.
The gravel is used should be of different sizes. There are three regions that should have different sized gravel. The area between the topmost part and the surface layer should be occupied with 0.5 to 1-inch gravel. The surface layer region should be made up of 3/8 - 0.5-inch sized gravel and the layer should be 6 inches deep. Lastly, the region where the inlet and outlet have been fixed should be filled with course sized gravel with size ranging from 1-3 inches. The gravel should be sieved, screened and cleaned to avoid cases of blockage. The inlet and outlet pipe need to be placed at the bottom of the gravel. The 1 ½ - 3-inch rock ought to be put first over the accumulation and conveyance funneling to a profundity of 24 inches and stretch out no less than 6 creeps from the channels. The fixed bowl ought to be loaded up with water first, so the effect of falling rock on the liner will be limited, and all the more plainly show complete evaluations.
The most effective plants that can help in this water treatment system are Cattails (Typha), bulrush (Scirpus), rushes (Juncus), and sedges (Carex). One can consider other plants that have fibrous roots and can withstand the winter climatic conditions. The wetland with these plants should be located at an angle where the plants are receiving direct and full sunlight. When planting, it’s important to ensure that the plants are free from disease and mold. The roots should always be moist where the plant shoots need to slightly exposed while the roots need to be deep into the water in the cell. (Indiana state department of health, 2000)
Maintenance and monitoring
Constructed wetland requires very minimal maintenance and supervision. However, there is a need to carry out an inspection every six months. One can uproot the unwanted plant species, dead plants and unblocking as well as cleaning up the pipes. Other activities can include replanting and installing barriers to prevent flooding. (Reed & Crites, 2007)
Conclusion and recommendation
This is a method that can be used to remove impurities from water sourced from different places. The wetland system can be applied in our homes to help improve water quality. However, it's recommendable that after the water has undergone all that process, treatment should be made by use, for instance, use of a chemical to make the water safe for human consumption. Therefore, construction of wetland can be a good system design aimed at improving water quality management.
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