Comparison on efficiency of various techniques in treatment of waste and sewage water – A comprehensive review

AbstractIn the present scenario, environmental laws have become stringent towards health, economy and reduction of pollution. The pollution is a result of discharge of various organic and inorganic substances into the environment. The sources of pollution include domestic agricultural and industrial water. Conventional techniques such as chemical precipitation, carbon adsorption, ion exchange, evaporations and membrane processes are found to be effective in treatment of waste and sewage water. Recently, biological treatments have gained popularity to remove toxic and other harmful substances. The objective of the paper is to make comprehensive review including the performance of each technique in treatment of waste and sewage water. The research directions are also suggested based on the review

Degradation of toxic aromatic compounds with microorganisms

The contribution of easily assimilated organic compounds in the biodegradation of xenobiotic compounds which cannot support cellular duplication has not been studied extensively yet. In this thesis, the biodegradation of 1,2-dichlorobenzene, 2,4-dichlorophenol and 4-Cl-m-cresol was studied separately in the continuous presence of glucose as a carbon source. The effect of the addition of glucose in order to enhance the biodegradation of 1,2-dichlorobenzene and 4-Cl-m-cresol has not been extensively studied yet. Biodegradation experiments were carried out, using two bacterial species, Pseudomonas sp. and Staphylococcus xylosus, which were isolated by polluted soils in a mining industry near Stratoni, Chalkidiki. These particular strains have been recently isolated and haven’t been used in biodegradation studies so far. More specifically, concerning S. xylosus, there are no particular references involving bioremediation processes of chloro-aromatic compounds, using this microorganism. In the beginning of the experiments, natural adaptation of each bacterium in the presence of each chloro-compound at low initial concentration 0.1 mM and glucose 0.1% was carried out, in order to enhance the degradative ability of each bacterial strain. During this period, the increment of the values of specific growth rate and percentage of consumption of each chloro-compound was evidenced in a short period of time, indicating also the important role of natural adaptation in the performance of each bacterial system. The end of the natural adaptation period was confirmed, when no further increment of the specific growth rate or the percentage of consumption was evidenced. The natural adaptation was followed by the cultivation of each bacterial species at higher initial concentrations of the chloro-compounds tested. More specifically, 2,4-dichlorophenol and 4-Cl-m-cresol were studied at concentrations up to 1.0 mM, whereas 1,2-dichlorobenzene was studied at concentrations up to 10.0 mM. Although the values of the initial concentrations were increased, growth of the microorganisms was evidenced. However, the specific growth rate value was decreased, due to inhibition related to the presence of the xenobiotic compounds studied. The inhibition in the microbial growth was quantified by determining the lethal concentration LC50, as well as the maximum specific growth rate μmax and the inhibition constant of growth Kig. The calculation of their values showed that bacterial cultures of Pseudomonas sp, were less inhibited by 1,2-dichlorobenzene, exhibiting the higher values of μmax at 0.214 h-1 and Kig at 1.13 mM. In addition kinetic studies were carried out, in order to estimate the remaining concentration of each chloro-compound and glucose in the medium. It was found that each chloro-compound follows first-order kinetics, whereas glucose follows zero-order kinetics. The respective kinetic constants were also calculated in each case. The total consumption of each chloro-compound has been completed at the end of the exponential phase of growth (approx. after 8 h)Η συμβολή των εύκολα αφομοιώσιμων πηγών άνθρακα στη βιοαποικοδόμηση ξενοβιοτικών ενώσεων, οι οποίες από μόνες τους δε μπορούν να υποστηρίξουν την ανάπτυξη των κυττάρων, δεν έχει αποτελέσει θέμα εκτεταμένης μελέτης μέχρι σήμερα. Στην παρούσα διατριβή μελετήθηκε η βιοαποικοδόμηση τριών αρωματικών χλωροπαραγώγων, του 1,2-διχλωρο-βενζολίου, της 2,4-διχλωρο-φαινόλης και της 4-Cl-μ-κρεζόλης, το καθένα χωριστά, παρουσία γλυκόζης, ως πηγής άνθρακα. Δύο βακτήρια χρησιμοποιήθηκαν για το σκοπό αυτό, η Pseudomonas sp. και ο Staphylococcus xylosus, τα οποία απομονώθηκαν από επιρυπασμένα εδάφη εξορυκτικής μεταλλευτικής δραστηριότητας, στο Στρατώνι Χαλκιδικής. Μέχρι σήμερα είναι γνωστό ότι το 1,2-διχλωρο-βενζόλιο και η 4-Cl-μ-κρεζόλη δεν έχουν μελετηθεί σε συνδυασμό με τη γλυκόζη. Ειδικότερα για την 4-Cl-μ-κρεζόλη δεν υπάρχουν μελέτες που να αφορούν στη βιοαποικοδόμηση αυτής ως τη μόνη οργανική ένωση στο θρεπτικό υγρό. Τα βακτήρια που χρησιμοποιήθηκαν είναι νέα στελέχη, καθώς δεν προέρχονται από κάποια τράπεζα μικροοργανισμών, ενώ ο Staphylococcus xylosus δεν έχει χρησιμοποιηθεί προηγουμένως σε διεργασίες βιοαποκατάστασης. Αρχικά πραγματοποιήθηκε η φυσική προσαρμογή του κάθε βακτηρίου με το κάθε χλωροπαράγωγο χωριστά σε χαμηλή συγκέντρωση 0.1 mM, παρουσία γλυκόζης 0.1% με σκοπό την ενίσχυση της βιοαποικοδομητικής ικανότητας του κάθε στελέχους. Κατά τη διάρκεια αυτής, διαπιστώθηκε αύξηση σε σύντομο χρονικό διάστημα των δύο σημαντικών παραμέτρων που αφορούν στην ανάπτυξη και στη βιοαποικοδομητική ικανότητα των μικροοργανισμών, δηλαδή του ειδικού ρυθμού ανάπτυξης και του ποσοστού κατανάλωσης όλων των χλωροπαραγώγων που μελετήθηκαν. Μετά το τέλος της φυσικής προσαρμογής, όπου δε διαπιστώθηκε περαιτέρω αύξηση του ειδικού ρυθμού ανάπτυξης και του ποσοστού κατανάλωσης, ακολούθησε η ανάπτυξη των στελεχών σε μεγαλύτερες συγκεντρώσεις χλωροπαραγώγων, συγκεκριμένα έως 1.0 mM παρουσία 2,4-διχλωρο-φαινόλης και 4-Cl-μ-κρεζόλης και έως 10.0 mM παρουσία του 1,2-διχλωρο-βενζολίου. Παρά τις υψηλότερες τιμές συγκεντρώσεων διαπιστώθηκε ανάπτυξη των στελεχών, η οποία χαρακτηρίστηκε από διαρκώς ελαττωμένες τιμές του ειδικού ρυθμού ανάπτυξης λόγω της παρεμπόδισης του χλωροπαραγώγου. Η παρεμπόδιση στην ανάπτυξη των δύο μικροοργανισμών εκφράστηκε τόσο με τον υπολογισμό της θανατηφόρου συγκέντρωσης LC50, όσο και με τον υπολογισμό του μέγιστου ειδικού ρυθμού ανάπτυξης μmax και της σταθεράς παρεμπόδισης ανάπτυξης Kig, σύμφωνα με τις τιμές των οποίων, τη μικρότερη παρεμπόδιση στην ανάπτυξη είχε το 1,2-διχλωρο-βενζόλιο με το βακτήριο Pseudomonas sp. (0.214 h-1 και 1.13 mM)

Enhancing Phenolic Content of Medicinal Aromatic Plants Extracts-Biofunctional Foods Preparation

In this study, the assessment of TPC and antioxidant activity enhancement of medicinal and aromatic plant (MAP) aqueous extracts using natural sweeteners or encapsulation materials was carried out. MAP extracts fortified with polyphenols were used to produce biofunctional chocolate bites. Honey or erythritol added to Melissa officinalis concentrated aqueous extracts exhibited TPC at 19.53 mg GAE/mL and 18.24 mg GAE/mL, respectively, and DPPH radical scavenging activity greater than 82%, comparing to its non-concentrated aqueous extract (3.74 mg GAE/mL and 72.9%, respectively). Honey added to MAP concentrated aqueous extract mixtures presented up to twofold higher TPC compared to M. officinalis concentrated aqueous extracts with honey. Chocolate bites with MAP concentrated aqueous extract mixtures and honey exhibited TPC and DPPH radical scavenging activity at 29.48 mg GAE/g chocolate and 93.7%, respectively. The addition of gum arabic or inulin in MAP concentrated aqueous extract mixtures increased the TPC up to 12-fold (40.37 mg GAE/mL and 34.14 mg GAE/mL, respectively) compared to its non-concentrated aqueous extracts (3.38 mg GAE/mL), whereas DPPH radical scavenging activity approached 99.5%. Honey incorporation as a sweetener and polyphenolic compound encapsulation in gum arabic can lead to the production of biofunctional foods with elevated cytoprotective action without compromising their organoleptic attributes

Removal of heavy metals using different polymer matrixes as support for bacterial immobilisation

Great attention is focused on the microbial treatment of metal contaminated environments. Three bacterial strains, 1C2, 1ZP4 and EC30, belonging to genera Cupriavidus, Sphingobacterium and Alcaligenes, respectively, showing high tolerance to Zn and Cd, up to concentrations of 1000ppm, were isolated from a contaminated area in Northern Portugal. Their contribution to Zn and Cd removal from aqueous streams using immobilised alginate, pectate and a synthetic cross-linked polymer was assessed. In most cases, matrices with immobilised bacteria showed better metal removal than the non-inoculated material alone. For the immobilisation with all the polymers, 1C2 was the strain that increased the removal of Zn the most, whereas EC30 was the most promising for Cd removal, especially when combined with the synthetic polymer with up to a ca. 11-fold increase in metal removal when compared to the polymer alone. Removal of individual metals from binary mixtures showed that there was differential immobilisation. There was greater removal of Cd than Zn (removals up to 40% higher than those showed for Zn). The results show that metal contaminated environments constitute a reservoir of microorganisms resistant/tolerant to heavy metals that have the capacity to be exploited in bioremediation strategies.Capsule immobilisation of bacteria in the naturally occurring alginate and pectate and in a synthetic cross-linked polymer increased the Zn and Cd removal abilities from single and binary contaminated waters; the applications with the synthetic polymer were the most promising for Cd and Zn removal in single and binary mixtures

Batch and column removal of total chromium from aqueous solution using Sargassum polycystum

10.1002/ep.10416Environmental Progress and Sustainable Energy293334-341ENVP