A Mini Review of the Techno-environmental Sustainability of Biological Processes for the Treatment of High Organic Content Industrial Wastewater Streams

The authors would like to acknowledge the Royal Society for funding the current research: Ad-Bio: Advanced Biological Wastewater Treatment Processes, Newton Advanced Fellowship -2015/R2. Theoni M. Massara is grateful to the Natural Environment Research Council (NERC) of the UK for the 4-year full PhD studentship

Removal of Heavy Metals by a Membrane Bioreactor Combined with Activated Carbon

Royal Society; Ad-Bio: Advanced Biological Wastewater Treatment Processes; Natural Environment Research Council (NERC): Newton Advanced Fellowship - 2015/R2

The effect of initial pH and retention time on boron removal by continuous electrocoagulation process

In this study, factors influencing boron removal via the continuous electrocoagulation process were investigated at lab-scale. Different influent pH values (4, 5, 6, 7.45 and 9) and contact times (10, 25, 50 and 100 min) were examined as variable parameters. Plate-type aluminium electrodes with 5 mm distance between them were used. All the experiments were conducted in continuous mode and the current density was kept constant at 5 A throughout the whole experimental period. The initial boron concentration was selected to be 1000 mg L-1. The first set of experiments concerning the influence of the influent pH showed that the highest boron removal (67%) was obtained at pH=6 since it was the optimal pH for boron precipitation through aluminium borate formation. Under the constant current density of the study and with the initial pH adjusted to 6, increasing the duration of the electrocoagulation process from 10 to 100 min resulted in raising the boron removal from 45 to 79% during the second set of experiments. The greater duration of the electrocagulation process enabled higher aluminium dissolution, thus allowing the existence of a higher number of coagulants within the reactor. Moreover, it enhanced boron precipitation because of the longer contact time between the boron ions and the coagulants. After optimizing significant parameters such as the influent pH and the electrocagulation duration, the continuous electrocoagulation process was found to constitute an effective alternative for boron removal

Removal of endocrine disrupting compounds in a lab-scale anaerobic/aerobic sequencing batch reactor unit

The fate and removal of six selected endocrine disrupting compounds in a lab-scale anaerobic/aerobic (A/O) sequencing batch reactor (SBR), operating at 5 days, solids retention time (SRT) were investigated. A carbamazepine (CBZ), acetaminophen (ATP), diltiazem (DTZ), butyl benzyl phthalate (BBP), estrone and progesterone mix was spiked as model endocrine disrupting compounds (EDC) into domestic wastewater obtained from a nearby sewage treatment plant. The influent, effluent and sludge samples from the SBR unit were analysed by using an LC/MS/MS instrument equipped with electrospray ionization. More than 80% removal was observed for all the EDCs tested. It was found that biodegradation is the most important mechanism for BBP, ATP and progesterone. Biodegradation constants were calculated according to the simplified Monod model for these compounds. The DTZ seemed to have lower rate of biodegradation. The CBZ appeared totally resistant to biodegradation. However, it presented a high rate of sorption onto the sludge and was thereby treated. This contradicts with the literature studies

EDC REMOVAL IN A LAB-SCALE PRE-ANAEROBIC SBR UNIT

Studies in the last two decades showed that effluents of wastewater treatment plants is the main source of endocrine disrupting compounds in fresh water systems and conventional wastewater treatment facilities fail to accomplish a full removal of many of these compounds due to their specific chemical properties. Different treatment mechanisms have been tested biological nutrient removing systems especially sequencing batch reactors (SBR) showed promising results

An ozone assisted process for treatment of EDC's in biological sludge

A novel aerobic sludge digestion process to stabilize and decrease the amount of excess sludge produced during biological treatment and removal of EDCs sorbed onto sludge during this process is discussed here. Waste activated sludge samples from two different wastewater treatment plants were ozonated for different periods in Erlenmeyer flasks once a day on each of four consecutive days. Flasks were continuously aerated between ozone applications by shaking on an orbital shaker. The residual EDC concentrations in sludge samples were analyzed at the end of digestion periods. An MLVSS reduction of up to 95% was achieved with an ozone dose of only 1.05 g O-3/kg MLSS in this process on the fourth day. During this process destruction of some selected endocrine disrupting compounds, namely diltiazem, carbamazepine, butyl benzyl phthalate, acetaminophen and two natural hormones, estrone and progesterone, which tend to accumulates in sludge, are studied. Over 99% removal of these contaminants were achieved at the end of the fourth day. The analyses were conducted by using LC (ESI) MS/MS after solid phase extraction (SPE). By this process it became possible to save on contact time as well as achieving a bio-solids digestion far exceeding the standard aerobic process and concomitant removal of micropollutants at the expense of minimum ozone dose. The developed process is deemed superior over side-stream ozonation of activated sludge, in that it does not cause reduction in active biomass in the aeration tank

Enhancement of bio-gas production and xenobiotics degradation during anaerobic sludge digestion by ozone treated feed sludge

Elimination of large amounts of sludge produced during biological treatment is a pressing environmental issue both in this country and elsewhere. For example EU Landfill Directive 99/31/EC [41] prohibits landfilling of both liquid and untreated wastes with a target to reduce the current amount of bio-degradable wastes, including sewage sludge, 50% and 65% by the years 2013 and 2020, respectively. Anaerobic digestion has now proven to be the most energy efficient way of destroying and stabilizing waste activated sludge and the methane by-product is a form of fuel. It is demonstrated in this research that anaerobic digestion of waste activated sludge, when coupled with mild ozone treatment (e.g., 1.33 mg O-3/g-VSS), practically doubles the volume of biogas produced as compared to conventional digesters, while producing no waste sludge for disposal. Ozone treatment of the feed sludge also affects enhanced removal of endocrine disrupting compounds, EDCs, sorbed onto the sludge

Determination of selected natural hormones and endocrine disrupting compounds in domestic wastewater treatment plants by liquid chromatography electrospray ionization tandem mass spectrometry after solid phase extraction

A new analytical method for the simultaneous determination of two natural hormones (progesterone and estrone) and two selected endocrine disrupter compounds (EDCs) (diltiazem and carbamazepine (Cbz)) was developed by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) after pre-concentration with solid phase extraction (SPE). Influent and effluent samples taken from five different wastewater treatment plants throughout Turkey namely Hurma/Antalya, Lara/Antalya, Kemer-1 and Kemer-2 and METU/Ankara were analyzed for their EDCs contents under the optimum conditions. All of the parameters in the pre-concentration step were optimized and the best recoveries for all compounds of interest were achieved at pH 7 (about 100%). Progesterone was not detected in any of the treatment plants while diltiazem was found in all samples with the exception of Lara effluent. © The Royal Society of Chemistry 2012