Korneliusz Miksch, Grzegorz Cema, Ewa Felis, Adam Sochacki
Politechnika Śląska, Gliwice
Abstract
The novel technologies used in environmental engineering were discussed in this paper – the formation of aerobic granules, the Anammox process, the advanced oxidation processes, the use of fungi for dyes decolorization, constructed wetlands, the soil phytoremediation supported by rhizosphere microorganisms and the use of molecular biology technique in environmental engineering.
The structure of granular sludge is influenced by EPS production. The average diameter and density of biogranules increase due to EPS production. Although polysaccharides are essential, proteins were found to be the predominant component of aerobic granular sludge. Compared to loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS) showed more significant correlations with granules formation. This investigation will contribute towards a better understanding of the behavior and composition of EPS in sequencing batch reactors.
The traditional nitrification and denitrification processes proceed well with typical municipal wastewater. Nevertheless, there are also nitrogen-rich wastewater streams like landfill leachate or reject waters from dewatering of digested sludge, for which traditional nitrification/denitrification can be generally ineffective due to free ammonia inhibition of nitrification and unfavorable biodegradable carbon content for denitrification. Because of high requirements for oxygen and the necessity for addition of external carbon source, treating such nitrogen-rich streams with nitrification/denitrification would become expensive and unsustainable. The least resources consuming pathway for the conversion of ammonium to nitrogen gas is a combination of partial nitrification and the Anammox process. The main advantages of this process compared to the conventional nitrification/denitrification are: low sludge production, decrease of the aeration costs by almost 60% (only half of the ammonia is oxidized to nitrite in the nitritation process without further oxidation to nitrate), and no need for external organic carbon source addition (Anammox process). Furthermore, anammox bacteria oxidize ammonium under anoxic conditions with nitrite as the electron acceptor, and converse energy for CO2 fixation. Additionally, the biomass yield of the Anammox process is very low (0.08 kg VSS kg NH4-N-1 in comparison to 1 kg VSS kg NH4-N-1 in conventional nitrification/denitrification process) consequently, little sludge is produced. The low sludge production is another factor that contributes to the substantially lower operation costs compared to conventional denitrification systems.
Advanced oxidation processes (AOPs) are oxidative methods which are based on the generation of the hydroxyl radicals, which are very reactive and less selective than other oxidants. In the wastewater treatment technology, AOPs can be used in a combination with conventional biological techniques (so called hybrid processes), as pre- and post- treatment processes. The advanced oxidation processes have been used in order to increase the biodegradability and also detoxification of the wastewater.
The ability of fungi to degrade lignin-cellulose debris is well known. In addition to these natural molecules they may also degrade synthetic compounds, including synthetic dyes. High effectiveness of Evans blue and brilliant green mixture removal by all tested strains was demonstrated. The process was the most effective and fast in shaken conditions. Finally strain MB removed 90% of tested mixture in shaken samples after 96h. It was the best result reached among all the strains used in the experiment. High removal efficiency was accompanied by a decrease of toxicity (from V class to III class in test with D. magna and from IV class even to non-toxic in test with L. minor). The highest decrease of phytotoxicity was noticed in samples with shaken biomass in which the effect of dyes mixture elimination was the best. The research indicates very high potential of tested strains for decolorization and detoxification of dyes mixture.
Constructed wetlands are man-made system mimicking the process occurring in natural wetlands. These systems are considered to be an alternative to more technically advanced waste water treatment technologies. The development of constructed wetlands is envisaged to pursue the following directions grouped according to: the type of the waste water to be treated, target contaminants, treatment intensification methods, ancillary benefits and the locality.
Mycorrhiza fungi can be used for phytoremediation proccess. They support plant growth by lowering the stress caused by the lack of phosphorus and water. They produce enzymes participating in several stages of xenobiotics decomposition, which is helpful in their further biodegradation performed by the other rhisospherical organisms. The natural colonisation of PAHs contaminated soil is a long-term process. It could be shortend by adding fungal propagules as an inoculum to the soil. Fungi used for the injections should be isolated from PAHs contaminated soil. That guarantees their survival and development in the contaminated environment. The level of PAHs elimination from soil depends on a type of bioremediation modification used. It was shown that the best results are obtained with monocotylous plants combined with bacterial and fungal biopreparations obtained from contaminated soil. The symbiosis of mycorrhiza fungi with monocotylous plants caused ca. 40% increase of 3, 4, 5 and 30% of 6-ring hydrocarbons removal from soil in comparison with the conventional methods.
Important aspect of environmental protection and engineering is the possibility for qualitative and quantitative monitoring of complex microbial communities, responsible for biotechnological processes, such as: soil bioremediation, wastewater treatment or composting.
Due to the fact that most of the environmental bacteria cannot be grown in the laboratory conditions molecular techniques are widely used in environmental engineering. Among these methods the Polymerase Chain Reaction (PCR)-based and hybridization-based (such as Fluorescent in situ Hybridization; FISH) techniques are known to be the most useful.
Słowa kluczowe:
tlenowe granule, zewnątrzkomórkowe polimery, częściowa nitryfikacja, proces Anammox, zaawansowane procesy utleniania, systemy hybrydowe, oczyszczalnie hydrofitowe, dekoloryzacja barwników, bioremediacji gruntów, mikoryza roślin, techniki biologii molekularne, PCR, FISH
050. Novel Methods and Technologies in Environmental Engineering
Keywords:
aerobic granules, granule formation, extracellular polymeric substances, partially nitrification, Anammox process, advanced oxidation processes, hybrid systems, constructed wetlands, decolorization, synthetic dyes, soil bioremediation, plant mycorrhization, molecular biology techniques, PCR, FISH
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Zadanie Czasopismo, Annual Set The Environment Protection Volume 17. Year 2015 (wersja elektroniczna) dofinansowane ze środków Ministerstwa Nauki i Szkolnictwa Wyższego
