Publikationsserver der RWTH Aachen University
Verfahrenskombination von Nanofiltration und Adsorption an Pulverkohle zur kontinuierlichen Abwasserreinigung
Abstract
dc:descriptionHighly contaminated waste waters (e.g. wastewater from textile dying processes or dumpsite leachate) have to be treated because of their high content of poorly biodegradable organics. A treatment process has to provide both a low cost sink for the organic contaminants and a near-complete removal of critical components. Single step processes can achive only one of these goals. Powdered adsorbents have to be used in high (i.e. expensiv) quantities for complete COD-removal (chemical oxigen demand) resulting in little loadings of the adsorbent (mass of eliminated contaminant per mass of adsorbent). Basically, nanofiltration (NF) presents a promising alternative for rejecting COD – but a highly concentrated brine is inevitable. For reducing the concentrates high recovery rates / concentration factors and, consequently, high COD concentrations are mandatory. But high concentrations lead to excessive osmotic pressures and thus reduced driving forces in the membrane process – low permeate fluxes need to be compensated with high membrane areas. Furthermore, high concentrations result (constant membrane rejection assumed) in higher permeate COD concentrations. As a result, the reduction of the concentrates is limited because of economical and ecological reasons. By performing adsorption on powdered adsorbents – e.g. lignite coke dust (LCD) or powdered activated carbon (PAC) – in an NF-module a new hybrid process was developed, which avoids the weaknesses of the single step processes while fully using their strengths: NF as a COD and solids barrier and the adsorbent as a cost effective sink for the organic contaminants. It could be proved experimentally that the proposed process enables reduced discharge concentrations, higher recovery rates / concentration factors and improved permeate fluxes compared to conventional nanofiltration applications. Based on experimental investigations in laboratory- and bench scale a plant for the treatment of 10 mä/h dumpsite lechate was designed. This capacity is identical with the size of the installed plant at the dumpsite Alsdorf-Warden from which the leachate for the experiments was taken. The specific treatment costs of the NF with upstream / combined adsorption are with 44 DM/mä approximately 50% of the treatment costs in Alsdorf-Warden if lignite coke dust is employed. If powdered activated carbon is added to the leachate upstream of the NF an AOX-concentration in the permeate can be reached that is 50% of the discharge limits at nearly identical treatment costs (46 DM/mä). But if the discharge limit for AOX – that presents the critical parameter for plant design – can already be reached with a traditional NF (without upstream / combined adsorption) this solution is recommended because of the lowest specific treatment costs of 43 DM/m3.
Degree
thesis:*- Grantor dc:publisher
- Publikationsserver der RWTH Aachen University
- Year dc:date
- 2000
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Eilers, Ludger
- Contributors dc:contributor
-
- Melin, Thomas
Subjects
dc:subject × 10Rights
dc:rights- Statement dc:rights
-
- info:eu-repo/semantics/openAccess
- Language dc:language
- ger