Aubron, T.1, van Afferden, M.1, Mosig, P.1, Rahman, K.1, Müller, R.A.1
1Helmholtz Centre for Environmental Research (UFZ), Environmental and Biotechnology Center – UBZ, Permoserstrasse 15, Leipzig, 04318 GERMANY (thomas.aubron@ufz.de)
Keywords:Ecotechnology; vertical flow filter, industrial pollution, organic compounds, hydrocarbons
Introduction
A rich and complex history of industrial activities, war-destruction, and economic turmoil has left Germany with more than 300 000 industrial contaminated sites presenting a threat to both the environment and the local populations. Many factories, chemical plants, and landfills remain in operation and sometimes still contribute to the contamination of rivers and aquifers.
As part of the regulation, these sites have been inventoried and, when possible, the cocktail of pollutants identified. The common mix of pollutants include biodegradable organic compounds such as BTEX, MTBE, aliphatic hydrocarbons and PAHs; “non-biodegradable”
organic compounds such as organochlorides as well as inorganic compounds such as sulphides and cyanides.
Physico-chemical treatment units (air stripping, adsorption, chemical oxidation…) have been extensively implemented to treat water/wastewater and bring pollutant concentrations below accepted limits (DVGW, 2001). Since 2007, the UFZ has tested ecotechnologies such as treatment wetlands for the same purpose. Compared to other conventional systems, ecotechnologies have proven to be effective, robust, inexpensive to operate and easy to maintain (van Afferden, 2011). Several treatment wetland pilot-scale investigations have been successfully validated and implemented at full-scale.
Material and Methods
As of January 2017, the UFZ has designed, operated and tested six pilots for the treatment of contaminated water with pollutant concentrations as high as 30,000 μg.L-1. The typical pilot-scale ecotechnology design consists of two or three stages of vertical flow filters. The first filter is dedicated to the pre-treatment of the influent while the second and/ third filters perform the main treatment. The coarse media (gravel or expended clay) used for the filters and the extremely high hydraulic load to applied (up to 4 m³.m-².d-1) limit the risk of ion precipitation that could otherwise induce clogging. Homogeneous distribution of the influent water is critical to ensure proper treatment.
Once the performance of a pilot plant meets the concentration limits, a scaling-up process can be initiated to prepare for a full-scale implementation. This process covers the aspects ranging from design to technical and operational specifications and from permitting procedures to cost estimation for feasibility and tendering.
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Results and Discussion
Of the six pilot plants already tested by the UFZ, one tested pilot has already been up-scaled (Leuna I) while one is under construction (Leuna II) and three have started an up-scaling process (Kupferhammer, Schwarze Pumpe and at the Chemical industry) (Table 1). Two pilots remain under investigation for further optimization. This successful use of ecotechnologies for remediation of industrially polluted water has attracted additional interest from the industry and governmental bodies, resulting in three new pilots being planned and another three being considered.
From an economic aspect, the cost savings for Leuna I alone are expected to reach approximately 2 Mio. € within the first five years of operation thanks to very low operation and maintenance costs and requirements.
Efficient treatment and economic advantages make ecotechnologies a very competitive treatment solution for treating industrial pollution. Successful projects are attracting the attention from stakeholders and the public. The high interest in the use of ecotechnologies stresses the need for more research to investigate pollutant degradation mechanisms and degradation of reportedly “non-biodegradable” compounds.
Alkylphenol 5000 to 16 000 99.5 Closed Construction in 2018
DVGW, 2001, DVGW, D.V.d.G.-u.W.e.V., 2001. Verordnung zur Novellierung der Trinkwasserverordnung vom 21. Mai 2001, Bonn, Germany (in German).
van Afferden M., Rahman K.., Mosig P., De Biase C., Thullner M., Oswald S., Müller R., Remediation of groundwater contaminated with MTBE and benzene: The potential of vertical-flow soil filter systems, Water Research, Volume 45, Issue 16, 15 October 2011, Pages 5063-5074, ISSN 0043-1354.
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Cleaning up landfill leachate in rural China with low-energy gas flotation and oxidation Kindler, J.1, Eckelberry, N.1
1OriginClear, Los Angeles, California, 525 S Hewitt Street, United States Keywords:landfill, leachate, wastewater, advanced oxidation, electroflotation Introduction
The aim of this work was to test the effectiveness of low-energy Electro Flotation and Advanced Oxidation to reduce contaminants present in landfill leachate from a rural northern China city landfill. The operator of this site required a solution beyond traditional treatment methods that require frequent maintenance. Goals for this demonstration were to reduce chemical oxygen demand (COD) from 10,000 mg/l to 100 mg/l and to reduce ammonia (NH4) from mid-300ppm to 8ppm. This demonstration was also an opportunity to show proof of concept of technology in a flow-through scenario and demonstrate effective treatment in real time.
A result of rain or ground water that flows through the municipal and industrial wastes in landfills, leachate is a highly contaminated and complex industrial effluent that can contaminate nearby soil, groundwater and surface water and lead to a health risk for local communities.
Many governments are taking note of the hazardous of landfill leachate and are updating discharge standards – in China, the EPA has already introduced new water discharge standards.
Current technologies to clean landfill leachate lack the long-term efficiency needed to remove leachate’s high contaminant load. As demand for responsible treatment of landfill leachate grows, operators require a reliable and cost-effective way to clean up this hazardous wastewater.
Material and Methods
A 7-step treatment process was used to maximize contaminant removal. The flow rate was set at approximately 12 liters per minute to match the full tank capacity of the Advanced Oxidation (AOx) module and optimize efficiency. Iron(II) Sulfate Heptahydrate and sodium hydroxide were added to the influent water in the holding tank to reduce biological oxygen demand (BOD), raise the pH to 10 and ease flocculation. The influent water then entered an Electro Water Separation (EWS) flotation unit, where suspended solids were separated and clumped together using anodic reactor tubes. The wastewater then flowed through an ultrafiltration (UF) membrane to improve clarity, and through an Advanced Oxidation unit with a pH of 8.7.
Hydrogen chloride (HCl) was added to the stream to bring the pH of the solution down to 6.5.
Finally, the wastewater flowed through an ultrafiltration (UF) membrane to remove trace contaminants and a reverse osmosis (RO) system for final polishing.
Results and Discussion
Following treatment, COD fell by 75%, Ammonia was reduced by 70% and Sulfur decreased
The IWA S2Small2017 Conference on Small Water & Wastewater Systems and Resources Oriented Sanitation
passing through a final RO membrane. Onsite testing showed final ammonia levels at 8ppm and a COD under 100. Interviews with end users in China suggest that existing leachate treatment costs roughly $10 - $15 per m3 and a cost analysis of this treatment method suggests that the total cost of this treatment ranges from $1.27 - $7.83 per m3 of wastewater. This is an economically viable treatment solution for rural China landfill managers.
Construction engineering is currently exploring options for retrofitting existing flotation units, as well as responsive residence time and energy input combinations to enable this process to adapt to contamination load variations over long periods of time. Additional studies will also optimize module performance and address the removal of total dissolved solids (TDS) or other contaminants that may only be partially removed by this low-energy treatment.
Metric (mg/l) Raw water Post-EWS % drop
COD 10,239 2,583 75
Ammonia 2,036 610 70
Sulfur 2,078 713 65
Figure 1: Lab results prior to RO treatment show a significant decrease in COD, Ammonia and Sulfur.
Further to this on-site demonstration, several test campaigns have been arranged using leachate from various sources and ages to assess this treatment system’s versatility and ability to handle influent variability. Subsequent tests were done in EWS:AOx lab cells having a batch treatment capability of 4 liters.
MK (China) 13,000 7,100 840 2,200 94% 69%
HK (China) 2,895 3,210* 656 11* 77% 97%*
WW
(Malaysia)**
830 13 335 0 60% 100%
LG (China) 2,975 3,500 1,000 610 66% 83%
NY (China) 2,058 23 204 0.5 90% 98%
YY (China) 67,584 10,460 16,477 402 76% 96%
Average 77% 90%
* Measured parameter is Total Nitrogen
** After initial biological treatment
References
Schiopu, Ana-Maria, Gavrilescu, Maria. “Options for the Treatment and Management of Municipal Landfill Leachate: Common and Specific Issues.” Clean Soil Air Water,vol. 36, no. 12, 2010, pp. 1101-1110. Accessed 13 Mar. 2017.