Marla C. Maniquiz

Multiple linear regression models of urban runoff pollutant load and event mean concentration considering rainfall variables.

Rainfall is an important factor in estimating the event mean concentration (EMC) which is used to quantify the washed-off pollutant concentrations from non-point sources (NPSs). Pollutant loads could also be calculated using rainfall, catchment area and runoff coefficient. In this study, runoff quantity and quality data gathered from a 28-month monitoring conducted on the road and parking lot sites in Korea were evaluated using multiple linear regression (MLR) to develop equations for estimating pollutant loads and EMCs as a function of rainfall variables. The results revealed that total event rainfall and average rainfall intensity are possible predictors of pollutant loads. Overall, the models are indicators of the high uncertainties of NPSs; perhaps estimation of EMCs and loads could be accurately obtained by means of water quality sampling or a long-term monitoring is needed to gather more data that can be used for the development of estimation models.

Characteristics of contaminants in water and sediment of a constructed wetland treating piggery wastewater effluent.

Constructed wetland (CW) is the preferred means of controlling water quality because of its natural treatment mechanisms and function as a secondary or tertiary treatment unit. CW is increasingly applied in Korea for secondary effluent of livestock wastewater treatment. This study was conducted to recognize the characteristics of contaminants in the accumulated sediment at the bottom soil layer and to reduce the phosphorus release from sediments of the free water surface CW for the treatment of secondary piggery wastewater effluent from a livestock wastewater treatment facility. The results revealed that the dominant phosphorus existence types at near the inlet of the CW were non-apatite phosphorus (59%) and residual phosphorus (32%) suggesting that most of the particles of the influent are made up of inorganic materials and dead cells. Sediment accumulation is important when determining the long-term maintenance requirements over the lifetime of CW. Continuous monitoring will be performed for a further assessment of the CW system and design.

Appropriate determination method of removal efficiency for nonpoint source best management practices

Abstract In Korea, best management practice (BMP) pilot facilities were installed to manage nonpoint source (NPS) pollution from the watershed areas. These BMPs are consistently monitored to determine the accurate pollutant removal efficiencies. However, the difficulty of removal efficiency determination in NPS BMPs is generally caused by uncertainties of site and storm characteristics. For that reason, removal efficiency determination has to apply appropriate method to eliminate uncertainties. In this study, the monitoring program was performed during 3 years in order to verify the efficiency of the infiltration trench during storm events. The pollutant removal efficiency was determined by four different methods namely the efficiency ratio (ER), summation of loads (SOL), regression of loads (ROL) and rainfall of frequency (ROF) methods. In comparison to other methods, the ROF method uses the rainfall frequency which is practical to eliminate uncertainties of NPS. Therefore, the ROF method is suggested as...

Unit soil loss rate from various construction sites during a storm

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.

Diffuse pollutant unit loads of various transportation landuses

ABSTRACT A four-year monitoring study was conducted to determine the diffuse pollutant unit loads for the six representative transportation landuses (i.e., highway, parking lot, bridge, service area and toll gate) in urban areas in Korea. Pollutant event mean concentrations (EMCs) were calculated from 123 storm events at eleven sites and the average annual rainfall and runoff coefficients were determined to estimate the unit loads using the National Institute of Environmental Research (NIER) method. Apparent differences in the unit load values existed among landuses as explained by the high variability of EMCs for different rainfall events. The study has found that runoff from bridges and highways contained the highest loadings of TSS and COD while service areas are the primary sources of nutrients and metals. The results of this study could be used by the Ministry of Environment (MOE) to separate the unit loads of transportation landuses from the urban area category in the current unit load system. The v...

Seasonal treatment efficiency of surface flow constructed wetland receiving high nitrogen content wastewater

Abstract This research investigated the performance of a constructed wetland (CW) that functions as a post-treatment unit for the secondary effluent of a piggery wastewater treatment facility. The pollutant mass removal efficiency was evaluated from 37 sampling events on non-rainy days during 2008–2010. Based on the findings, the pollutant concentrations decreased somewhat along the cells from the influent to the effluent while DO and pH increased along the cells and appeared to peak at the deep marsh region during the spring season. The overall cumulative treatment efficiencies for the entire monitoring period were 53% for total suspended solids; 35–37% for biological oxygen demand and chemical oxygen demand; 33% for total phosphorous; and 17–21% for total nitrogen and other nitrogen forms. The main reason for the low treatment performance was attributed to the low carbon to nutrient ratio (i.e., the COD/BOD:TN:TP ratio) in the CW influent. Moreover, algal bloom was frequently observed in the deep marsh ...

Performance comparison between infiltration and non-infiltration type of structural stormwater treatment systems.

The study was constructed to monitor representative inflow and outflow from infiltration and non-infiltration type best management practice (BMP) sites developed at a university campus, allowing the determination of overall performance efficiency in terms of runoff reduction and pollutant removal. Based on the monitored storm events, the runoff and discharged volume and flow rates exhibited high positive correlations with total rainfall depth (p<0.001). Findings revealed that as the total rainfall increases, the amount of volume reduction and pollutant removal decreases for both types of BMP. Infiltration BMP showed a higher ability in treatment performance especially during small storm events than non-infiltration type; however, the differences were not significant. Pollutant removal rates of infiltration type were in the range of 70-90% while between 35 and 80% for the non-infiltration type for storm events with less than 10 mm rainfall depth. Average volume reductions were 71 ± 33% and 32 ± 32% for the infiltration and non-infiltration type, respectively. The ratio of the discharge volume was significantly greater than the ratio of discharge pollutant load indicating a high potential for water quality improvement. Design recommendations were provided considering sizing and cost for on-site application of similar BMP designs in the future.

Characteristics of contaminant and phosphorus existence types in sediment of a constructed wetland

ABSTRACT This research investigated the physical and chemical characteristics of sediment deposited at the bottom soil layer of free water surface flow constructed wetland (CW) treating runoff impacted stream water from an agricultural area which is important when determining the long-term maintenance requirements over the lifetime of the CW. Based on the findings, the influent to the CW still was polluted with high concentration of nutrients with TN and TP exceeding five and two times the water quality standard in rivers and lakes. The accumulation of sediment at the first treatment unit (sedimentation zone) of the CW augmented after the summer season signifying that the dredging of sediment must be conducted after the rainy season or until before the winter season. It was found out that the main phosphorus (P) types existing at the sediment in the CW were residual-P (R-P) and non-apatite-P (NAI-P) constituting to almost 90% of total P. While NAI-P can be released in the natural environment by increasing...

Stormwater runoff monitoring in a deciduous and coniferous forest

ABSTRACT 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 significant 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 significantly 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 significantly different for TN (p = 0.16) and TP (p = 0.17). No correlations were identified between the pollutant EMCs and rainfall variables. The pollutant and flow patterns were used to provide ...

Flow and mass balance analysis of eco-bio infiltration system

A structured stormwater infiltration system was developed and constructed at a university campus and monitoring of storm events was performed during a oneyear operation period. The flow and pollutant mass balances were analyzed and the overall efficiency of the system was assessed. While significant positive correlations were observed among rainfall, runoff and discharge volume (R2= 0.93–0.99; p<0.05), there was no significant correlations existed between rainfall, runoff, discharge volume and pollutant load. The system was more effective in reducing the runoff volume by more than 50% for small storm events but the difference between the runoff and discharge volume was significant even with rainfall greater than 10 mm. Results showed that the pollutant reduction rates were higher compared to the runoff volume reduction. Average pollutant reduction rates were in the range of 72% to 90% with coefficient of variation between 0.10 and 0.46. Comparable with runoff reduction, the system was more effective in reducing the pollutant load for small storm events, in the range of 80% to 100% for rainfall between 0 and 10 mm; while 65% to 80% for rainfall between 10 and 20 mm. Among the pollutant parameters, particulate matters was highly reduced by the system achieving only a maximum of 25% discharge load even after the entire runoff was completely discharged. The findings have proven the capability of the system as a tool in stormwater management achieving both flow reduction and water quality improvement.