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Stabilization Ponds
Published in Subhash Verma, Varinder S. Kanwar, Siby John, Environmental Engineering, 2022
Subhash Verma, Varinder S. Kanwar, Siby John
Where the facultative lagoons are organically overloaded, some artificial aeration is used to maintain aerobic conditions in the top layer. However, aeration is limited to allow some settling and keep the bottom layer anaerobic. This idea was originally used to upgrade overloaded facultative lagoons where expansion was not possible. Aerated facultative lagoons can handle as much as 10 times more loading. Detention time can be as small as two to five days compared to 10 to 30 days in a normal facultative lagoon.
Process variables that defined the phytofiltration efficiency of invasive macrophytes in aquatic system
Published in International Journal of Phytoremediation, 2023
Yetunde Irinyemi Bulu, Nurudeen Abiola Oladoja
The use of macrophytes, as remediators, improved the physicochemical properties of wastewater. Mahmood et al. (2005) showed that P. crassipes reduced the values of BOD and COD (mg/L) in textile wastewater by a range of 40%–70%, and a 50.64% reduction in the total solids within four days. AN was removed to a greater extent, when compared with the other forms of nitrogen, with a 64% efficiency reduction in 3 weeks by P. crassipes, and a corresponding reduction in the values of COD and BOD by 41% and 61%, respectively (Rezania et al.2016). The efficiency of P. crassipes for sewage treatment was demonstrated by McDonald and Wolverton (1980) in the study of a facultative lagoon, at a loading rate of 44 kg/ha/d. At full coverage of P. crassipes, the values of the BOD5, total suspended solids, and the total organic carbon concentration were reduced to 23, 6, and 40 mg/L from an initial value of 161, 125, and 93 mg/L, respectively. In the absence of P. crassipes, these three parameters were reduced from 127 to 52 mg/L for BOD5, 140 to 77 mg/L for the total suspended solids and 66–72 mg/L for the total organic carbon concentration. Falbo and Weaks (1990) noted that P. crassipes caused a reduction of 24% and 33% in sulfate and acidity, respectively in an acid mine wastewater within a spate of 70 d. The study also reported an 8.78% reduction in the level of manganese after 14 d (Falbo and Weaks 1990).
Natural wetlands contribution on phosphorus removal in small northern communities in Canada
Published in Environmental Technology, 2023
Vanja Karpisek, MD Tanvir Hasnine, Nazim Cicek, Qiuyan Yuan
Various other wastewater treatment facilities exist for nutrient reduction. For instance, chemical precipitation generates more sludge, which results in a higher cost for sludge management. In addition, sludge stabilization, thickening, dewatering and transportation are highly energy-intensive processes. In terms of lagoons, using chemical precipitants generate sludge in which phosphorus is bound with iron or aluminium oxides and hydroxides and is not as readily available for growing plants if the sludge was land applied. When a natural wetland is receiving wastewater, there is an opportunity for environmental enhancement and significant cost savings [25–27]. Among different wastewater treatment technologies such as Waste Stabilization Pond (WSP), Activated Sludge Process (ASP), Trickling Filters, and Sequential Batch Reactor (SBR); natural wetland has been considered as most sustainable and efficient in terms of land area requirement, cost effectiveness and removal efficiency [28–30]. Therefore, this research focuses on the efficiency of natural wetlands as an effluent polishing step in removing phosphorus from wastewater in the northern continental environment. The Northern community of Manitoba, Canada has been chosen because a major portion of the aboriginal population especially First Nation (North American Indian) people lives there. In addition, the facultative lagoon system of that community treated domestic wastewater and seasonally discharges effluent into a wetland that connects to Lake Manitoba which is one of the largest lakes in the Manitoba province. This study is significant as it indicates the importance of natural wetland under cold climate conditions as an effluent polishing step to satisfy regulatory requirements for phosphorus reduction. The specific objectives of this research include the assessment of phosphorus removal efficiency from lagoon treated wastewater through the natural wetland and to understand water movement and phosphorus accumulation in the soil during the vegetation growing season.