The study used activated algae granules for low-strength wastewater treatment in sequential batch mode. Each treatment cycle was conducted within 24 h in a bioreactor exposed to 235 μmol/m²/s light intensity. Wastewater treatment was performed mostly in aerobic conditions, oxygen being provided by microalgae. High removal efficiency of chemical oxygen demand (COD) was achieved (86-98%) in the first hours of the reaction phase, during which the indicator's removal rate was 17.4 ± 3.9 mg O₂/g h; NH(4)(+) was removed during organic matter degradation processes with a rate of 1.8 ± 0.6 mg/g h. After almost complete COD removal, the (O⁺) remaining in the liquor was removed through nitrification processes promoted by the increase of the liquor's oxygen saturation (O₂%), the transformation rate of NH4(+) into NO(3)(-) increasing from 0.14 ± 0.05 to 1.5 ± 0.4 mg NH4(+)/g h, along with an O₂% increase. A wide removal efficiency was achieved in the case of PO(4)(3)(-) (11-85%), with the indicator's removal rate being 1.3 ± 0.7 mg/g h. In the provided optimum conditions, the occurrence of the denitrifying activity was also noticed. A large pH variation was registered (5-8.5) during treatment cycles. The granular activated algae system proved to be a promising alternative for wastewater treatment as it also sustains cost-efficient microalgae harvesting, with microalgae recovery efficiency ranging between 99.85 and 99.99% after granules settling with a velocity of 19 ± 3.6 m/h.
The focus of this study was to assess the treatment performance and granule progression over time within a continuous flow reactor. A continuous flow airlift reactor was seeded with aerobic granules from a laboratory scale sequencing batch reactor (SBR) and fed with dairy wastewater. Stereomicroscopic investigations showed that the granules maintained their integrity during the experimental period. Laser diffraction investigation showed proof of new granules formation with 100-500 μm diameter after only 2 weeks of operation. The treatment performances were satisfactory and more or less similar to the ones obtained from the SBR. Thus, removal efficiencies of 81-93% and 85-94% were observed for chemical oxygen demand and biological oxygen demand, respectively. The N-NH(+)(4) was nitrified with removal efficiencies of 83-99% while the nitrate produced was simultaneously denitrified - highest nitrate concentration determined in the effluent was 4.2 mg/L. The removal efficiency of total nitrogen was between 52 and 80% depending on influent nitrogen load (39.3-76.2 mg/L). Phosphate removal efficiencies ranged between 65 and above 99% depending on the influent phosphate concentration, which varied between 11.2 and 28.3 mg/L.
The balance between biotechnological useful microorganisms species, as well as the aerobic sludge granules morphology influences the treatment plant performance. This paper presents an attempt to correlate the experimental results on wastewater treatment performance with aerobic granular sludge structural community. The experiments were conducted in two lab scale bioreactors operated in parallel at different retention times. Treatment performances achieved in both systems lead to an effluent that complies NTPA001 limits, both systems being able of simultaneous nitrification / denitrification and phosphorus removal. For qualitative and quantitative analysis of aerobic granular sludge specific microorganisms, DNA has been succeesfully isolated and purifyied from sludge samples, thus obtaining bacterial DNA extracts in concentrations of up to 56 ng/mL and 78% purity. The resulted DNA extracts were used for qPCR amplification. Amplification was carried out in the presence of a series of 10 pairs of primers for the detection / quantification of specific bacteria and genes involved in the treatment process: universal bacteria; Micotrix parvicella; Ammonia oxidizing archaea; Ammonium monooxigenase; Nitrobacter Sp.; nitrite reductase; N2O reductase; phosphorus accumulating microorganisms. The experimental results showed a qualitative and quantitative improvement of the sludge quality in terms of species distribution and share of biotechnologically useful bacteria.
The growth of population has been linked with the increase usage of chemical compounds design for domestic and industrial use. At its turn, the increased amount of the chemical compound puts an enhanced stress on the environment. In such scenario, the waste management, including the wastewater treatment strategies have become an important part for the environmental protection. Unfortunately, the wastewater treatment procedures have several components which could be improved. Among them aeration process and biomass sedimentation have been the most stringent to tackle, since the aeration alone consume more than 60% from wastewater treatment energy cost. In this study, we proposed a new microalgae-bacteria activated sludge granule which could be an economical and technological solution to the above mentioned issues such as aeration and sedimentation. Moreover, during this study we characterized the physical, morphological and chemical characteristic of the newly formed granules by advances techniques such as electronic and correlative microscopy.
Using aerobic granular sludge for wastewater treatment has multiple advantages compared to conventional activated sludge systems, most important being the ability of simultaneous removal of the pollutants responsible for eutrophication: organic load, compounds of nitrogen (NH 4 + ;) and phosphorus (PO 4 3-). The advantages are currently exploited for developing the next generation of wastewater treatment systems while the identified limitations are approached by experimental and theoretical researches worldwide. The aim of the study consists in evaluating the possibility of predicting the system's response to different changes in the influent wastewater loadings. The paper presents simulations results backed up by experimental data for pollutants removal efficiencies evaluation for a sequential batch reactor (SBR) with aerobic granular sludge. The mathematical model is based on the activated sludge model no. 3, which was updated by considering the simultaneous biological nitrification (NH 4 + àNO 3 -) and denitrification (NO 3 -àN 2 á) processes, thus complying with the biochemical reactions occurring in aerobic granular sludge sequential batch reactors. The model developed was validated by the experimental results obtained on a laboratory scale SBR monitored for over a month.Following wastewater treatment, the discharge water quality parameters have to comply the legislation limits, the strictest and most difficult to acquire being the ones for total phosphorous and total nitrogen concentrations, with values of 2 and respectively 15 mg/L [1].At a national scale, the biological wastewater treatment stage is based on activated sludge, removing the organic matter and, depending on the plant configuration, nutrients.Aerobic granular sludge-based biological wastewater treatment processes [2,3] has an important role at present due to the multiple advantages of granules when compared to activated sludge flocs, including the dense structure, improved settling properties, superior biomass concentration and higher capacity to withstand load shocks [4,5].Obtaining a stable activated granular sludge in sequential batch reactors (SBRs) is dependent on granules selection factors (sedimentation time, percentage of total extracted volume, depth and duration of effluent discharge) [6].Using modeling and simulation tools can provide consistent information on processes efficiencies and limitations under specific changes in the influent compounds concentration [7]. Extended studies have been focused on using simulation tools for full-scale wastewater treatment systems in order to evaluate different scenarios for increasing the treatment performances [8].The initial simulations of aerobic granulation process were based on empirical models based on logistic curves [9] or phenomenological linear equations [10]. This category of models is mostly based on experimental results and can't be transferred to other cases without extensive adaptation according to the new conditions.Mathematical models for simulating aerobic granular sludge ev...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.