DESIGN OF WETLAND SYSTEM FOR WASTEWATER QUALITY IMPROVEMENT AT FORMOSA HA TINH STEEL COMPANY

After a marine life disaster in central Viet Nam in 2016 due to poorly treated steel industry wastewater and pipe cleaning solutions, the Formosa Steel Corporation has been improved their wastewater treatment systems. Besides, an effluent polishing and buffer pond – wetland system has to be built. The study team has run the 500 m2 pilot wetland aiming to figure out optimum design parameters such as: balancing requirements of hydraulic conductivity, hydraulic headloss, filtration efficiency and plant growth. The pilot wetland was filled with different kind of lime stone, peanut gravel and sand, running with flow rate 49.5-122.4 m3/h. The pilot test results have provided appropriate design parameters for the 4.3 ha Formosa wetland: Subsurface flow constructed wetland cells CB1, CB2, CB3 placed in series, with maximum horizontal flow rate 122 m3/h, unit hydraulic headloss 22.8cm/100m, followed by free water surface flow wetland cell CB4. The main filtration media selected for wetland cells CB1, 2, 3 was lime stone with diameter 50-100 mm (60 cm depth), where supporting layers for plant vegetation were coarse sand (20cm depth) and peanut gravel of 5-10 mm diameter (10 cm depth). The full scale 10 ha pond-wetland system now is in operation, proving design configurations of the team.

Bioinformatics Analysis of Microbial Abundance and Diversity in Acid Mine Drainage from the Solomon Mine Near Creede, Colorado

This study focused on characterizing the phylotypic composition of acid mine drainage (AMD) communities associated with the Solomon Mine near Creede, Colorado, and its relative diversity compared to microbial communities found in the East Willow Creek (EWC) watershed. AMD from the Solomon Mine adit flows into an existing passive bioremediation wetland system located next to the Solomon Mine adit that currently is ineffective and is under consideration for renovation. We are interested in gaining an understanding of the baseline microbial communities present in AMD/EWC and to monitor them during future wetland renovation. Prokaryotic community profiling was approached using SSU 16S rRNA marker gene amplification coupled with next generation sequencing. Bioinformatics analysis included raw read preprocessing, data visualization, and statistical testing using a combination of USEARCH and QIIME-based scripts. A pH and conductivity gradient were observed for water moving through the currently inefficient wetland system at the Solomon Mine. The EWC microbiomes had statistically significant higher alpha diversity compared to the AMD microbiomes. Beta diversity analysis parsed the sample locations into statistically significant groups including core AMD microbiomes, the wetland Cell 3 microbiome, and EWC microbiomes using multidimensional scaling. Taxa driving beta diversity included the phylum Proteobacteria for the core AMD microbiomes, the phyla Firmicutes and Chloroflexi for the constructed wetland Cell 3, and the phyla Bacteroidetes and Verrucomicrobia for EWC. Our data suggests that the microbial community in constructed wetland Cell 3 is likely where limited sulfate reduction activity is operating at low capacity, which will be further investigated via shotgun metagenomic analysis.

Design, construction and performance of a horizontal subsurface flow wetland system in Australia

Malabugilmah is a remote Aboriginal community located in Clarence Valley, Northern NSW, Australia. In 2006, seven horizontal subsurface flow wetland clusters consisting of 3 m × 2 m wetland cells in series were designed and constructed to treat septic tank effluent to a secondary level (Total Suspended Solids (TSS) < 30 mg/L and Biochemical Oxygen Demand (BOD5) <20 mg/L) and achieve >50% Total Nitrogen (TN) reduction, no net Total Phosphorus (TP) export and ≥99.9% Faecal Coliform (FC) reduction. The wetland cell configuration allowed the wetlands to be located on steeper terrain, enabling effluent to be treated to a secondary level without the use of pumps. In addition to the water quality targets, the wetlands were designed and constructed to satisfy environmental, economic and social needs of the community. The wetland systems were planted with a local Australian wetland tree species which has become well established. Two wetland clusters have been monitored over the last 4 years. The wetlands have demonstrated to be robust over time, providing a high level of secondary treatment over an extended period.

Effects of intermittent loading on nitrogen removal in horizontal subsurface flow wetlands

Removal of CBOD5 and nitrogen from septic tank effluent was evaluated in four horizontal subsurface flow (HSSF) wetlands. An intermittently loaded cell was compared to a continuously loaded control cell, with both treatments receiving the same weekly volume. The intermittent cell was rapidly drained and “rested” for 24-hr, then refilled in steps, twice weekly. Two media with different particle sizes but similar porosities were also compared. The two media, light weight expanded shale and gravel, were both continuously loaded. As hypothesized, the wetland cell that was intermittently loaded had higher dissolved oxygen, greater ammonia removal, and greater nitrate production than the continuously loaded cells. Areal NH3-N removal for the intermittently loaded cell was 0.90 g m−2 d−1 compared to 0.47 g m−2 d−1 for the control. Ammonia removal was also higher in continuously loaded gravel cells than in cells with expanded shale. Ammonia-N removal was an order of magnitude lower in a similar SSF wetland that had been in operation for 3 years. However, CBOD5, total suspended solids, and total nitrogen did not vary substantially among the treatments.

Reversing clogging in subsurface-flow constructed wetlands by hydrogen peroxide treatment: two case studies

One of the most frequently encountered operational problems in subsurface-flow constructed wetlands is clogging. Traditionally, the restoration procedure is to remove the clogged gravel or sand and replace it with clean material. This method, while effective, is costly and may require sections of the facility to be taken offline for extended periods of time. Another common remediation strategy is to have a resting period for each wetland cell, although this is not an option for very small systems which often consist of only one treatment cell. Recently, a more radical approach has been tested on a number of lab-scale and pilot-scale setups which consists of an aggressive oxidation of organic matter by means of hydrogen peroxide (H2O2). Results indicate that after treatment, clogging was substantially reduced and that H2O2 did not appear to have a long-term negative effect on plants and biofilms. The outcomes of two full-scale tests are discussed in this paper.

Geoarcheological Investigations of Wetland Cell D Within the Dallas Floodway Extension Project Area, Dallas, Texas

The Dallas Floodway Extension project is designed to provide flood damage reduction and environmental restoration within the Trinity River flood plain between the Corinth Street Viaduct and Loop 12. The U.S. Army Corps of Engineers, Fort Worth District, contracted with Geo-Marine, Inc., to conduct an archeological assessment of the proposed Wetland Cell D. The archeological assessment was to identify any potential archeological sites that may be eligible for inclusion in the National Register of Historic Places and to provide an assessment of the potential for buried landforms in the project area that may have intact archeological resources present. The geoarcheological investigations, involving the excavation of 10 backhoe trenches and the review of previous data collected within the Upper Trinity River drainage, revealed that the flood plain sediments of the Trinity River are quite variable, both horizontally and vertically. The data collected during the current investigations suggest that Cell D is located along or near the axis of a recent Trinity River meander belt that has cut deeply into the preexisting Quaternary sediments. This channel cut was then rapidly filled with fine-grained deposits possibly derived from the surrounding uplands and other areas upstream. In addition, the trenching revealed that the upper portions of the sediments within Cell D have been disturbed during the recent historic period, presumably by the construction of the Interstate 45 bridge and the activities of the nearby Dallas Central Wastewater Treatment Plant.

Treatment of Nitrogen and Phosphorus by a Constructed Upland-Wetland Wastewater Treatment System

An Upland-Wetland wastewater treatment system was installed in Pamlico County, North Carolina in September 1989 to test its effectiveness in wastewater treatment for a single family home. Treatment effectiveness was evaluated from March 1990 to September 1991. The mound provided an aerobic environment that resulted in complete nitrification and reduction of phosphorus. Concentration of total nitrogen (TN) was lowered 64%, from 44.4 mg/L to 16.0 mg/L by the mound component. Nitrogen in the wastewater dosed into the mound was in the ammonium (NH4N) and organic forms, while essentially all the nitrogen present in water that had passed through the mound was in the nitrate (NO3N) form. The mound lowered total phosphorus (TP) concentration 86%, from 4.4 mg/L to 0.6 mg/L. The wetland cell planted with Phragmites australis was more effective than both the implanted cell and the cell planted with Typha angustifolia. Concentrations of (TN), primarily NO3N, were lowered from 16.0 mg/L to 11.1 mg/L or of that entering the cell. Total phosphorus was lowered 31%, from 0.6 mg/L to 0.3 mg/L. The Upland-Wetland Wastewater Treatment System has provided low cost, low maintenance and effective wastewater treatment.