Abstract
The objective of this study was to identify the factors affecting the suspended and fixed biomass in the removal of hard COD, nitrogenous compounds and phenols from a coal gasification wastewater (CGWW) stream using a hybrid fixed-film bioreactor (H-FFBR) process under real-time plant operational conditions and actual wastewater composition. The composition of the influent and effluent was studied to determine which compounds were not removed by hydrolysis (bacterial activity) and how this correlated to the suspended and fixed biomass activity, COD and phenol removal. A H-FFBR with 12 g∙m −3 attached biomass and 440 mg∙l −1 suspended biomass achieved 78% phenol removal and 49% COD removal but insignificant removal of nitrogenous compounds. During the operation period, fixed biomass concentration was higher than the suspended biomass. Parameters such as pH, phenols, alkalinity, metal ions, conductivity, total dissolved solids and aeration rate affected the fixed biofilm properties such as adhesion, thickness and structure. It can be concluded that the composition of the effluent had a direct effect on the fixed biomass properties and thus a direct effect on the removal of phenols, COD and nitrogenous compounds in the wastewater. Keywords : ammonia stripping, AnoxKaldness, coal gasification, fixed-biofilm reactor, hydantoins, phenosolvan, Pseudomonas, refinery effluent, thiocyanate
Highlights
Coal gasification wastewater (CGWW) is generated in coal gas purification which poses numerous environmental problems in many countries
The Phenosolvan process employs a liquid-liquid extraction process where the incoming gas liquor is filtered through a gravel bed and contacted with the solvent di-isopropyl ether (DIPE) (Beychok, 1974) or butyl ethanoate (Anastasi, 1980) in multistage mixer-settlers (Beychok, 1974; Bryant et al, 1988)
The compounds identified in the coal gasification wastewater (CGWW) were phenols, straight-chain carboxylic acids, aromatic carboxylic acids, ketones, diesel range organics (DRO), hydroquinones, indoles and hydantoins
Summary
Coal gasification wastewater (CGWW) is generated in coal gas purification which poses numerous environmental problems in many countries. The generated wastewater can contain ammonia, cyanide, thiocyanate, monohydric phenols, dihydric phenols, polycyclic hydroxyl compounds, monocyclic n-aromatics, polycyclic aromatics and aliphatic acids. Of these compounds the phenolic components, primarily, methyl-phenol, and phenols, constitute between 60 and 80% of the organic content (Li et al, 2003). Physico-chemical methods for the extraction of the phenolic content have been realised in order to reduce the toxicity of the waste stream before conventional treatment. Such treatments as the Phenosolvan process for phenol recovery have been investigated. The liquor is steam-stripped to remove acid gases (hydrogen sulphide and carbon dioxide), followed by steam-stripping to remove ammonia (Beychok, 1974)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
