Fouling of reverse osmosis and nanofiltration membranes by diary industry effluents

2002 ◽  
Vol 45 (12) ◽  
pp. 355-360 ◽  
Author(s):  
M. Turan ◽  
A. Ates ◽  
B. Inanc
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Biological Treatment ◽  
Specific Energy Consumption ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Total Hardness ◽  
Feed Tank ◽  
Layer Resistance

Fouling experiments of nanofiltration (NF) and reverse osmosis (RO) are reported for treatment of the effluent of chemical-biological treatment plant and the original effluent of dairy industry respectively. In the experiments, a thin film composite type of spiral wound was used and fitted with flowmeters and pressure sensors. The feed water was stored into a feed tank and passed a fine filter and was pumped to membrane. Brine and permeate were recirculated back to the feed tank. Membrane fouling was investigated with 16 and 30% water recovery of a single membrane at different pressures and flowrates for RO and NF membranes respectively. Fouling is evaluated with a relationship between relative flux (J/Jo) which is the ratio of the flux at any time during the fouling test to the initial flux and relative resistance (Rf/Rm) which is the ratio of fouling (cake) layer resistance to clean membrane resistance. Turbidity, conductivity, chemical oxygen demand (COD), total suspended solids (TSS) and total hardness were measured in the feed and permeate side of each membrane. The effluent total hardness concentrations of chemical-biological treatment plant were found greater than the influents. The results are presented in terms of the relative flux as a function of time related to hydrodynamic conditions and pollution characteristics of wastewater. The permeate water flux of RO membrane decreases more rapidly than NF membrane. the relative flux decreases with increasing the fouling layer resistance, Rf onto membrane surface. 50% the drop of permeate flux was observed for RO and NF membranes after 50 h and 80 h of operation, respectively. The fouling rate increases with an increase in the concentration of the wastewater constituents in the dairy industry. The relative flux decreased 10 and 20% with increasing chemical oxygen demand (COD) from 5,000 mgl−1 to 10,000 mgl−1 and from 45 mgl−1 to 450 mgl−1 for RO and NF membranes, respectively after 45 h of time. Fouling of membranes resulted in 100% increase of specific energy consumption as the relative permeate fluxes of NF and RO membranes decreased 30 and 40% respectively. The average of specific energy consumption was obtained at 6 and 10 kWhm−3; consequently, operational costs were estimated at U.S. $0.45 m−3 and U.S. $0.75 m−3 for NF and RO units respectively. Also, operational cost for chemical-biological treatment was found at U.S. $0.30 m−3.

scholarly journals Energy consumption of agitators in activated sludge tanks – actual state and optimization potential

2017 ◽  
Vol 77 (3) ◽  
pp. 800-808 ◽  
Author(s):  
K. Füreder ◽  
K. Svardal ◽  
W. Frey ◽  
H. Kroiss ◽  
J. Krampe
Keyword(s):  
Energy Consumption ◽  
Power Density ◽  
Specific Energy ◽  
Operating Time ◽  
Specific Energy Consumption ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Actual State ◽  
Total Energy Consumption ◽  
Continuous Mixing

Abstract Depending on design capacity, agitators consume about 5 to 20% of the total energy consumption of a wastewater treatment plant. Based on inhabitant-specific energy consumption (kWh PE120−1 a−1; PE120 is population equivalent, assuming 120 g chemical oxygen demand per PE per day), power density (W m−3) and volume-specific energy consumption (Wh m−3 d−1) as evaluation indicators, this paper provides a sound contribution to understanding energy consumption and energy optimization potentials of agitators. Basically, there are two ways to optimize agitator operation: the reduction of the power density and the reduction of the daily operating time. Energy saving options range from continuous mixing with low power densities of 1 W m−3 to mixing by means of short, intense energy pulses (impulse aeration, impulse stirring). However, the following correlation applies: the shorter the duration of energy input, the higher the power density on the respective volume-specific energy consumption isoline. Under favourable conditions with respect to tank volume, tank geometry, aeration and agitator position, mixing energy can be reduced to 24 Wh m−3 d−1 and below. Additionally, it could be verified that power density of agitators stands in inverse relation to tank volume.

scholarly journals Electrooxidation Using Nb/BDD as Post-Treatment of a Reverse Osmosis Concentrate in the Petrochemical Industry

2019 ◽  
Vol 16 (5) ◽  
pp. 816 ◽  
Author(s):  
Salatiel Wohlmuth da Silva ◽  
Carla Venzke ◽  
Júlia Bitencourt Welter ◽  
Daniela Schneider ◽  
Jane Zoppas Ferreira ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Energy Requirement ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Inorganic Ions ◽  
Oxidation Time ◽  
Kinetic Regime ◽  
Boron Doped Diamond

This work evaluated the performance of an electrochemical oxidation process (EOP), using boron-doped diamond on niobium substrate (Nb/BDD), for the treatment of a reverse osmosis concentrate (ROC) produced from a petrochemical wastewater. The effects of applied current density (5, 10, or 20 mA·cm−2) and oxidation time (0 to 5 h) were evaluated following changes in chemical oxygen demand (COD) and total organic carbon (TOC). Current efficiency and specific energy consumption were also evaluated. Besides, the organic byproducts generated by EOP were analyzed by gas chromatography coupled to mass spectrometry (GC–MS). The results show that current densities and oxidation time lead to a COD and TOC reduction. For the 20 mA·cm−2, changes in the kinetic regime were found at 3 h and associated to the oxidation of inorganic ions by chlorinated species. After 3 h, the oxidants act in the organic oxidation, leading to a TOC removal of 71%. Although, due to the evolution of parallel reactions (O2, H2O2, and O3), the specific energy consumption also increased, the resulting consumption value of 66.5 kW·h·kg−1 of COD is considered a low energy requirement representing lower treatment costs. These results encourage the applicability of EOP equipped with Nb/BDD as a treatment process for the ROC.

scholarly journals Batch Reverse Osmosis Desalination Modeling under a Time-Dependent Pressure Profile

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 173
Author(s):  
Abdeljalil Chougradi ◽  
François Zaviska ◽  
Ahmed Abed ◽  
Jérôme Harmand ◽  
Jamal-Eddine Jellal ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Energy Demand ◽  
Specific Energy Consumption ◽  
Pressure Profile ◽  
Recovery Ratio ◽  
Feed Concentration ◽  
Energetic Performance ◽  
Feed Volume

As world demand for clean water increases, reverse osmosis (RO) desalination has emerged as an attractive solution. Continuous RO is the most used desalination technology today. However, a new generation of configurations, working in unsteady-state feed concentration and pressure, have gained more attention recently, including the batch RO process. Our work presents a mathematical modeling for batch RO that offers the possibility of monitoring all variables of the process, including specific energy consumption, as a function of time and the recovery ratio. Validation is achieved by comparison with data from the experimental set-up and an existing model in the literature. Energetic comparison with continuous RO processes confirms that batch RO can be more energy efficient than can continuous RO, especially at a higher recovery ratio. It used, at recovery, 31% less energy for seawater and 19% less energy for brackish water. Modeling also proves that the batch RO process does not have to function under constant flux to deliver good energetic performance. In fact, under a linear pressure profile, batch RO can still deliver better energetic performance than can a continuous configuration. The parameters analysis shows that salinity, pump and energy recovery devices efficiencies are directly linked to the energy demand. While increasing feed volume has a limited effect after a certain volume due to dilution, it also shows, interestingly, a recovery ratio interval in which feed volume does not affect specific energy consumption.

scholarly journals Energy efficiency of staged reverse osmosis (RO) and closed-circuit reverse osmosis (CCRO) desalination: a model-based comparison

2020 ◽  
Vol 20 (8) ◽  
pp. 3096-3106
Author(s):  
Simeng Li ◽  
Karla Duran ◽  
Saied Delagah ◽  
Joe Mouawad ◽  
Xudong Jia ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Numerical Models ◽  
Specific Energy Consumption ◽  
Closed Circuit ◽  
Two Stage ◽  
One Stage ◽  
Multi Stage

Abstract Reverse osmosis (RO) technologies have been widely implemented around the world to address the rising severity of freshwater scarcity. As desalination capacity increases, reducing the energy consumption of the RO process per permeate volume (i.e., specific energy consumption) is of particular importance. In this study, numerical models are used to characterize and compare the energy efficiency of one-stage continuous RO, multi-stage continuous RO, and closed-circuit RO (CCRO) processes. The simulated results across a broad range of feed salinity (5,000–50,000 ppm, i.e., 5–50 g kg−1) and recovery (40%–95%) demonstrate that, compared with the most common one-stage continuous RO, two-stage and three-stage continuous RO can reduce the specific energy consumption by up to 40.9% and 53.6%, respectively, while one-stage and two-stage CCRO can lead to 45.0% and 67.5% reduction, respectively. The differences in energy efficiencies of various RO configurations are more salient when desalinating high-salinity feed at a high recovery ratio. From the standpoints of energy saving and capital cost, the simulated results indicate that multi-stage CCRO is an optimal desalination process with great potential for practical implementation.

scholarly journals Electrocoagulation for spent coolant from machinery industry

2017 ◽  
Vol 8 (4) ◽  
pp. 497-506 ◽  
Author(s):  
W. Pantorlawn ◽  
T. Threrujirapapong ◽  
W. Khanitchaidecha ◽  
D. Channei ◽  
A. Nakaruk
Keyword(s):  
Energy Consumption ◽  
Current Density ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Industrial Wastes ◽  
Electrolysis Time ◽  
Current Densities ◽  
Sludge Production

Abstract Spent coolant is considered as one of the most polluting industrial wastes and causes environmental problems. It mostly contains high non-biodegradable organic carbon and oil contents; the biodegradability index was very low at 0.04, which is difficult to be effectively treated by common treatment systems. Electrocoagulation (EC) was proposed for a pre-treatment of coolant. The laboratory-scale of EC reactor was developed with Al electrodes and 10 mm of interelectrodes. The efficiency of the EC reactor on chemical oxygen demand (COD) removal was investigated at various current densities and electrolysis times. The highest current density of 50 mA/cm2 induced a short electrolysis time of 10 min to reach the steady state of approximately 65% COD removal. When lower current densities of 20–40 mA/cm2 were supplied to the EC reactor, COD removal efficiency of 65% can be achieved at longer electrolysis times. According to the specific energy consumption and sludge production, the optimal condition for spent coolant treatment was the current density of 20 mA/cm2 and electrolysis time of 30 min in which a COD removal of efficiency of 68% was obtained, 0.88 kWh/kg-COD of the specific energy consumption and 0.04 kg/kg-COD of the sludge production.

Towards energy neutrality by optimising the activated sludge process of the WWTP Bochum-Ölbachtal

2016 ◽  
Vol 73 (12) ◽  
pp. 3057-3063 ◽  
Author(s):  
S. T. Marner ◽  
D. Schröter ◽  
N. Jardin
Keyword(s):  
Energy Consumption ◽  
Activated Sludge ◽  
Energy Demand ◽  
Biological Treatment ◽  
Specific Energy Consumption ◽  
Treatment Plant ◽  
Treatment Efficiency ◽  
Process Modification ◽  
Self Sufficiency ◽  
Energy Audits

Abstract As a result of Ruhrverband's regularly performed energy audits the wastewater treatment plant (WWTP) Bochum-Ölbachtal shows substantial deficits concerning energy efficiency. Due to the energy consumption of internal recirculation, mixers and return activated sludge (RAS) pumping the existing pre-denitrification process configuration offers a specific energy consumption for biological treatment of 23 kWh (PE · a)−1. In order to optimise the energy situation and to improve the treatment efficiency, the process layout was changed completely to a three-stage step-feed process. By optimising the hydraulic conditions, it was possible to reconstruct the plant with a free flow throughout the whole biological treatment system without any additional pumping. The total investment costs for this process scheme were 3.9 million €. These costs could be partly offset against the wastewater charge paid (2.9 million €). Compared to the overall energy consumption before the process modification, today the energy consumption for biological treatment amounts to 12.4 kWh (PE · a)−1. The highest saving potential has been achieved by optimising mixing and reducing the energy demand for internal recirculation and RAS pumping. In the case of the WWTP Bochum-Ölbachtal, the modification of the treatment process not only results in an improved energy situation but also increased the treatment efficiency in such a way that the nitrogen concentration in the effluent could be constantly kept below 5 mg L−1 Ntot, which provides the basis for being exempted from the wastewater discharge for nitrogen. As a result of all these measures, the rate of self-sufficiency by using biogas from the digester in combined heat and power units has been increased substantially from 60% before process modifications to 97%. With the upcoming optimisation measures, a further increase of self-sufficiency is expected to finally achieve energy neutrality based on yearly averages. The example of the WWTP Bochum-Ölbachtal clearly shows that it is worthwhile to consider further measures for improving the energy and treatment efficiency, although most of the machinery was not fully depreciated at the time of implementing the new concept. It is also evident that the regular energy monitoring is essential for identifying potential for improvement. In this context and based on Ruhrverband's experience, it is highly suggested that energy audits are performed regularly for larger WWTPs.

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