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Understanding the factors influencing the removal of heavy metals in urban stormwater runoff
Maniquiz-Redillas, Marla C.,Kim, Lee-Hyung IWA Publishing 2016 Water Science & Technology Vol.73 No.12
<P>In this research, an infiltration trench equipped with an extensive pretreatment and filter bed consisting of woodchip, sand and gravel was utilized as a low impact development technique to manage stormwater runoff from a highly impervious road with particular emphasis on heavy metal removal. Findings revealed that the major factors influencing the removal of heavy metals were the concentration of the particulate matters and heavy metals in runoff, runoff volume and flow rates. The reduction of heavy metals was enhanced by sedimentation of particulates through pretreatment. Fine particles (<2 mm) had the most significant amount of heavy metals, thus, enhanced adsorption and filtration using various filter media were important design considerations. Sediment was most highly attached on the surface area of woodchip than to other filter media like sand, gravel and geotextile. It is suggested that maintenance must be performed after the end of the winter season wherein high sediment rate was observed to maintain the efficiency of the treatment system.</P>
Treatment performance of a constructed wetland during storm and non-storm events in Korea
Maniquiz, M. C.,Lee, S. Y.,Choi, J. Y.,Jeong, S. M.,Kim, L. H. IWA Publishing 2012 Water Science & Technology Vol.65 No.1
<P>The efficiency of a free water surface flow constructed wetland (CW) in treating agricultural discharges from stream was investigated during storm and non-storm events between April and December, 2009. Physico-chemical and water quality constituents were monitored at five sampling locations along the flow path of the CW. The greatest reduction in pollutant concentration was observed after passing the sedimentation zone at approximately 4% fractional distance from the inflow. The inflow hydraulic loading, flow rates and pollutant concentrations were significantly higher and variable during storm events than non-storm (baseflow) condition (<I>p <</I>0.001) that resulted to an increase in the average pollutant removal efficiencies by 10 to 35%. The highest removal percentages were attained for phosphate (51 ± 22%), ammonium (44 ± 21%) and phosphorus (38 ± 19%) while nitrate was least effectively retained by the system with only 25 ± 17% removal during non-storm events. The efficiency of the system was most favorable when the temperature was above 15 °C (i.e., almost year-round except the winter months) and during storm events. Overall, the outflow water quality was better than the inflow water quality signifying the potential of the constructed wetland as a treatment system and capability of improving the stream water quality.</P>
Stormwater runoff monitoring in a deciduous and coniferous forest
Maniquiz, Marla Chua,Choi, Jiyeon,Lee, Soyoung,Kim, Lee-Hyung Balaban Publishers 2012 Desalination and water treatment Vol.38 No.1
<P> Fifteen storm events were monitored from April to October 2008 to investigate the stormwater runoff pollutant concentrations on a deciduous and coniferous forest in Korea. Based on the initial monitoring assessment, the average pollutant concentrations of stormwater runoff from the two forest sites were minor and not very signifi cant in comparison to urban areas in Korea. In addition, the levels of pollutants from the forest sites were lower than the average stream water quality and could be considered as background concentration of forest sites. The results indicated that the pollutant event mean concentrations (EMCs) from the deciduous forest were signifi cantly greater than the coniferous forest (p < 0.02) for all the measured pollutant parameters that include BOD, COD, DOC, SS, TN and TP; hence, not signifi cantly different for TN (p = 0.16) and TP (p = 0.17). No correlations were identifi ed between the pollutant EMCs and rainfall variables. The pollutant and fl ow patterns were used to provide guidance to a more appropriate sampling method, i.e., collection of optimum number of samples at optimum time interval. Based on the concentration data and rainfall, the sampling time interval could be selected and used in the subsequent monitoring. </P>
Development of statistical linear regression model for metals from transportation land uses
Maniquiz, Marla C.,Lee, Soyoung,Lee, Eunju,Kim, Lee-Hyung IWA Publishing 2009 Water Science & Technology Vol.59 No.12
<P>The transportation landuses possessing impervious surfaces such as highways, parking lots, roads, and bridges were recognized as the highly polluted non-point sources (NPSs) in the urban areas. Lots of pollutants from urban transportation are accumulating on the paved surfaces during dry periods and are washed-off during a storm. In Korea, the identification and monitoring of NPSs still represent a great challenge. Since 2004, the Ministry of Environment (MOE) has been engaged in several researches and monitoring to develop stormwater management policies and treatment systems for future implementation. The data over 131 storm events during May 2004 to September 2008 at eleven sites were analyzed to identify correlation relationships between particulates and metals, and to develop simple linear regression (SLR) model to estimate event mean concentration (EMC). Results indicate that there was no significant relationship between metals and TSS EMC. However, the SLR estimation models although not providing useful results are valuable indicators of high uncertainties that NPS pollution possess. Therefore, long term monitoring employing proper methods and precise statistical analysis of the data should be undertaken to eliminate these uncertainties.</P>
Unit soil loss rate from various construction sites during a storm
Maniquiz, Marla C.,Lee, Soyoung,Lee, Eunju,Kong, Dong-Soo,Kim, Lee-Hyung IWA Publishing 2009 Water Science & Technology Vol.59 No.11
<P>The Korean Ministry of Environment (MOE) opts to establish an ordinance having a standard specifying an allowable soil loss rate applicable to construction projects. The predicted amount of soil loss from a construction site exceeding the standard can be used to calculate the percent reduction necessary to comply with the ordinance. This research was conducted to provide a basis to establish a standard by investigating the unit soil loss rates in the three phases of development: pre-construction, active construction and post construction based from 1,036 Environmental Impact Assessment (EIA) reports within the six-year period (2000-2005). Based on the findings, several factors affect the magnitude of soil loss rates particularly storm characteristics, site slope, soil type, location from rivers, as well as the type of construction activity. In general, the unit soil loss rates during the active construction phase are extremely higher in comparison to undisturbed areas; in magnitude of 7 to 80 times larger in urban areas and 18 to 585 times in rural areas. Only between 20 to 40 percent of the soil loss rates was contributed at pre- and post- construction phases indicating that the active construction phase is the most important phase to control.</P>