Determining the optimal share of coke sludge in a mixture of communal sludge in order for the fermentation process to proceed smoothly. The results may be used in the utilization of industry waste.
The aim of the research was co-fermentation of municipal sludge with coke sludge, including conversions of polycyclic aromatic hydrocarbons (WWA) and polychlorinated biphenyls (PCB).
Co-fermentation was performed in glass bioreactors. The sludge was incubated at 37˚C for 16 days away from the light. In order to provide adequate contact between biomass and substrate, the reactors were manually mixed once a day. In order to determine the course of the process, indications of selected physico-chemical properties of the sludge were performed before the process, as well as after 4, 8, 12 and 16 days of incubation. In the sludge, the following were marked: dry residue, content of organic substance and hydration. In liquids obtained from sludge centrifugation: pH, alkalinity, chemical oxygen demand and volatile fatty acids. Both in the solid state (centrifugated sludge) as liquid state (oversendimentary liquids) WWA and PCB were marked before the process and after 4, 8, 12 and 16 days of fermentation in selected samples.
History of execution
The studies were carried out within the framework of the project “DoktoRIS – Program stypendialny na rzecz innowacyjnego Śląska” [scholarship program for innovative Silesia]. The project is co-financed with the funds from EU, within the framework of European Social Fund (agreement no 300025/76/2014; 300025/76/2014/2).
Effect of implementation
Disposal of coke sludge with communal sludge in the process of co-Fermentation is possible Addition of coke sludge to initial, excessive or communal sludge, (a mixture of initial and excessive) with the preservation of adequate proportion of mixing has no statistically significant influence on the degree of decomposition of organic substances, loss of dry mass, total production of biogas, reduction of organic substances expressed with ChZTindicator, production of biogas, content of methane in biogas and does not cause changes of technical parameters of the process. During the fermentation of methane, statistically significant differences of WWA and PCB contents in sewage sludge were noted, as well as the possibilities of degradation of these compounds.
Information on achieved innovations
The possibility of disposal of coke sludge with communal sludge in the process of fermentation is an innovative solution of the conducted research and research analysis. Determining an optimal share of coke sludge in the mixture of communal sludge in order for the fermentation to proceed smoothly. The results may be used in the process of industrial sludge utilization.
Impact of the result on: development of science, economy, society
Sludge, generated during sewage treatment, accounts for a substrate, which needs to be disposed of and/or managed effectively. Fermentation, carried out mainly in large urban sewage treatment plants, is one of the methods of biochemical stabilization of sludge. The aim of sewage sludge processing is decomposition of organic compounds, decreasing the volume of sludge, preparation for further processing, utilization or management. The choice of method of disposal depends of physico-chemical properties of the sludge and from the presence of toxic substance. There is, therefore, the problem of disposal of coke sludge heavy loaded with complex material to biodegrade, including polycyclic aromatic hydrocarbons and polychlorinated biphenyls. Coke sludge is exported by external companies and stored which generates additional costs, or burnt in coking batteries together with carbon, which, in turn, causes additional WWA emission to atmosphere and deteriorates coke quality. Therefore the process of co fermentation may be an effective solution of coke sludge utilization and contribute to the reduction of emission of selected micro pollution of the environment.