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Hassard F.,Cranfield University | Biddle J.,Bluewater Bio | Cartmell E.,Cranfield University | Stephenson T.,Cranfield University
Process Safety and Environmental Protection | Year: 2016

The impact of using different plastic mesh in rotating biofilm reactors (RBRs) on the treatment performance, biofilm activity and viability under varying organic loading rates (OLRs) was investigated. Laboratory-scale RBRs treating real wastewater were operated under OLR loading conditions typical of pre-treatment processes. A fully-crossed, three-factorial design series of experiments was undertaken with low and high surface area mesh made from polyvinyl chloride (PVC) and polypropylene (PP) operated at low, medium, high and very high OLR. The maximum volumetric removal rate of 2.4 kg sCOD m3 d−1 occurred at the high OLR, for low surface area mesh, irrespective of plastic used. The highest OLR at which nitrification could be attained was 35 g sCOD m−2 d−1. The biofilm growth decreased under medium compared to low OLR on all mesh. This coincided with a ∼2 fold decrease in the microbial viability. Higher surface area mesh was important for high nitrification rates at medium OLR (p < 0.05). In contrast the low surface area PVC and PP mesh was best at very high OLR (160 g sCOD m−2 d−1 or ∼320 g BOD5 m−2 d−1) for bulk organics removal (p < 0.05). Therefore, lower surface area mesh is recommended for wastewater pre-treatments at high OLR, whilst high surface area mesh was best for elevated nitrification rates at medium OLR. The microbial activity and viability had a strong positive correlation with OLR (R2 = 0.92, p < 0.001 and 0.81, p < 0.001 respectively). The microbial activity and viability also positively correlated (R2 = 0.4, p < 0.05 and 0.29, p < 0.01 respectively) to the sCOD removal performance but not the ammonia removal in mesh RBRs. This confirms the importance of maintaining biofilm activity and viability for bulk organics removal in biofilm processes in wastewater treatment. © 2016 The Authors

Hassard F.,Cranfield University | Biddle J.,Cranfield University | Biddle J.,Bluewater Bio | Cartmell E.,Cranfield University | And 3 more authors.
Process Safety and Environmental Protection | Year: 2015

Rotating biological contactors (RBCs) for wastewater treatment began in the 1970s. Removal of organic matter has been targeted within organic loading rates of up to 120 g m-2 d-1 with an optimum at around 15 g m-2 d-1 for combined BOD and ammonia removal. Full nitrification is achievable under appropriate process conditions with oxidation rates of up to 6 g m-2 d-1 reported for municipal wastewater. The RBC process has been adapted for denitrification with reported removal rates of up to 14 g m-2 d-1 with nitrogen rich wastewaters. Different media types can be used to improve organic/nitrogen loading rates through selecting for different bacterial groups. The RBC has been applied with only limited success for enhanced biological phosphorus removal and attained up to 70% total phosphorus removal. Compared to other biofilm processes, RBCs had 35% lower energy costs than trickling filters but higher demand than wetland systems. However, the land footprint for the same treatment is lower than these alternatives. The RBC process has been used for removal of priority pollutants such as pharmaceuticals and personal care products. The RBC system has been shown to eliminate 99% of faecal coliforms and the majority of other wastewater pathogens. Novel RBC reactors include systems for energy generation such as algae, methane production and microbial fuel cells for direct current generation. Issues such as scale up remain challenging for the future application of RBC technology and topics such as phosphorus removal and denitrification still require further research. High volumetric removal rate, solids retention, low footprint, hydraulic residence times are characteristics of RBCs. The RBC is therefore an ideal candidate for hybrid processes for upgrading works maximising efficiency of existing infrastructure and minimising energy consumption for nutrient removal. This review will provide a link between disciplines and discuss recent developments in RBC research and comparison of recent process designs are provided (Section 2). The microbial features of the RBC biofilm are highlighted (Section 3) and topics such as biological nitrogen removal and priority pollutant remediation are discussed (Sections 4 and 5). Developments in kinetics and modelling are highlighted (Section 6) and future research themes are mentioned. © 2014 The Institution of Chemical Engineers.

Hassard F.,Cranfield University | Cartmell E.,Cranfield University | Biddle J.,Bluewater Bio | Stephenson T.,Cranfield University
Water Science and Technology | Year: 2014

The impact of organic loading rate (OLR) on carbonaceous materials and ammonia removal was assessed in bench scale rotating media biofilm reactors treating real wastewater. Media composition influences biofilm structure and therefore performance. Here, plastic mesh, reticulated coarse foam and fine foam media were operated concurrently at OLRs of 15, 35 and 60 g sCOD m-2 d-1 in three bench scale shaft mounted advanced reactor technology (SMART) reactors. The sCOD removal rate increased with loading from 6 to 25 g sCOD m-2 d-1 (P < 0.001). At 35 g BOD5m -2 d-1, more than double the arbitrary OLR limit of normal nitrifying conditions (15 g BOD5 m-2 d-1); the removal efficiency of NH4-N was 82 ± 5, 27 ± 19 and 39 ± 8% for the mesh, coarse foam and fine foam media, respectively. Increasing the OLR to 35 gm-2 d-1 decreased NH 4-N removal efficiency to 38 ± 6, 21 ± 4 and 21 ± 6%, respectively. The mesh media achieved the highest stable NH 4 +-N removal rate of 6.5 ± 1.6 gm-2 d-1 at a sCOD loading of 35 g sCOD m-2 d-1. Viable bacterial numbers decreased with increasing OLR from 2 x 10 10-4 x 109 cells per ml of biofilm from the low to high loading, suggesting an accumulation of inert non-viable biomass with higher OLR. Increasing the OLR in permeable media is of practical benefit for high rate carbonaceous materials and ammonia removal in the pretreatment of wastewater. © IWA Publishing 2014.

Bluewater Bio | Entity website

Bluewater Bio Limited, a leading provider of innovative high-performance, cost-effective water and wastewater treatment technologies, is pleased to announce that Yorkshire Water Services Ltd (Yorkshire Water) has selected the Companys high rate filter technology, FilterClear, for their full-scale P removal Read more

Bluewater Bio | Entity website

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