Removing Organic Matter and Nutrients from Pig Farm Wastewater with a Constructed Wetland System

Abstract

Pollutants from pig farms in Mexico have caused problems in many surface water reservoirs. Growing concern has driven the search for low-cost wastewater treatment solutions. The objective of this research was to evaluate the potential of an in-series constructed wetland to remove nutrients from wastewater from a pig farm. The wetland system had a horizontal flow that consisted of three cells, the first a surface water wetland, the second a sedimentation cell, and the third a subsurface flow wetland. The vegetation used was Thypa sp. and Scirpus sp. A mix of soil with red volcanic rock (10–30 mm diameter) and yellow sand (2–8 mm diameter) was used as a substrate for the vegetation. The experiments were carried out in duplicate. Water samples were collected at the inflow and outflow of the cells. Two hydraulic retention times (HRT) (5 and 10 days) and three treatments were evaluated: 400, 800, and 1200 mg·L−1 of chemical oxygen demand (COD) concentration. Data was collected in situ for temperature, pH, dissolved oxygen (DO), electrical conductivity (EC), and total dissolved solids (TDS). COD, total Kjeldahl nitrogen (TKN), ammonia nitrogen (NH3–N), and total phosphorous (TP) were analyzed in the laboratory. The results showed that the in-series constructed wetland is a feasible system for nutrient pollutant removal, with COD removal efficiency of 76% and 80% mg·L−1 for a 5- and 10-day HRT, respectively. The removal efficiency for TKN, NH3–N, and TP reached about 70% with a 5-day HRT, while a removal of 85% was obtained with a 10-day HRT. The wetland reached the maximum removal efficiency with a 10-day HRT and an inflow load of 400 mg·L−1 of organic matter. The results indicate that HRT positively affects removal efficiency of COD and TDS. On the other hand, the HRT was not the determining factor for TP removal. Treatment one, with an initial COD concentration of 400 mg·L−1, had the highest removal of the assessed pollutants, allowing for the use of water for irrigation according to Mexican regulatory standards (NOM-001). The water quality resulting from treatments two and three (T2 = 800 mg·L−1 of COD and T3 = 1200 mg·L−1 of COD) did not comply with minimal requirements for irrigation water.

Assessing the Effects of Land Use on Surface Water Quality in the Lower uMfolozi Floodplain System, South Africa

“…High salt concentrations in the water or soil can reduce the portability of water and adversely affect plant productivity [ 52 ]. Furthermore, high EC can cause the inability of vegetation to compete for ions in water and soil causing toxicity of particular ions [ 53 ] such as chloride, sodium, etc. However, in terms of irrigation classes for fitness use [ 51 ], EC fell between good and marginal values.…”

Constructed Wetlands in Latin America and the Caribbean: A Review of Experiences during the Last Decade

“…ICW Some of these technologies are relatively new and have been used to treat highly loaded waters where a high oxygen demand is necessary, e.g., run-off from anti-icing fluids in airports [192], waters from food production [193], and petroleum industry discharges [194]. ICW also included in this review shows the use of hybrid systems in different configurations and operational schemes in the region; e.g., recirculation of HSSFW and VF systems [39,88], hybrid systems (combining HSSFW and VF systems) [41,140,161] aerated systems [67, 103,121], using algae turf filters [89] and microalgae ponds [98], evapotranspirative systems [114], and the use electroactive bacteria-based constructed wetlands (METland) [58] in the region. The ICW has been used to treat wastewater from domestic sewage [89,114,121], coffee production [67,103], swine [161], and landfill leachate [88].…”

Effectiveness of two-stage horizontal subsurface flow constructed wetland planted with Cyperus alternifolius and Typha latifolia in treating anaerobic reactor brewery effluent at different hydraulic residence times

“…For instance, the higher HRT or lower pollutant loading rate brings pollutants to have a higher rate of contact time within the treatment system (Reed et al 1995); favors greater chances of TSS sedimentation, and COD degradation, including high nutrient absorption and retention (Guo et al 2017), and improves the effluent quality. According to Mora-orozco et al (2018), a comparison of different treatment wetland efficiencies with the removal of solids and organic matter at different HRTs revealed that the 10 days HRT showed the highest removal efficiency than 5 days HRT. Sultana et al (2016) also showed that 8 days HRT removed 100% COD.…”

“…Many studies have also recognized that sufficient contact time has a significant role in the TSS and COD removal since it offers both particles to settle, and improve the removal efficiencies through adhering rather than absorbed by vegetation (Mora-orozco et al 2018;Winanti et al 2018). Also, the biological process has a main role in the removal of organic matter through microbiological degradation with bacteria attached to macrophyte roots (Winanti et al 2018).…”

“…Macrophyte species richness provides increased biomass production, which may greatly enhance nutrient reductions due to the increased nutrient retentions, microbial activity, and macrophytes uptake (Geng et al 2017). Although HRT plays a significant role in the effectiveness of nutrient removal in a CW, the longer HRT can provide the best formation of microbial communities and adequate contact time to remove nutrients (Mora-orozco et al 2018). Research evidence showed that shorter HRTs of 2-4 days, achieved over 90% of TSS and COD, 75% of TN and TP, respectively (Cheng et al 2010).…”