REMOVAL OF ORGANICS IN SEWAGE AND SECONDARY EFFLUENT BY REVERSE OSMOSIS

The UVC/H2O2 process was studied at laboratory scale for the treatment of one moderate (conductivity ∼8 mS/cm) and two high salinity (∼23 mS/cm) municipal wastewater reverse osmosis concentrate (ROC) samples with varying organic and inorganic characteristics. The process efficiency was characterized in terms of reduction of dissolved organic carbon (DOC), chemical oxygen demand (COD), colour and absorbance at 254 nm (A254), and the improvement of biodegradability. The reduction of colour and A254 was significantly greater than for DOC and COD for all samples due to the greater breakdown of humic compounds, as confirmed by fluorescence excitation-emission matrix spectra. Fairly small differences in the reduction of DOC (26–38%) and COD (25–37%) were observed for all samples, suggesting that the salinity of the ROC did not have a significant impact on the UVC/H2O2 treatment under the test conditions. The biodegradability of the treated ROC samples improved markedly (approximately 2-fold) after 60 min UVC/H2O2 treatment. This study indicates the potential of UVC/H2O2 treatment followed by biological processes for treating high-salinity concentrate, and the robustness of the process where the characteristics of the secondary effluent (influent to RO) and thus resultant ROC vary significantly.

Download Full-text

Preliminary study on novel backwash cleaning for reverse osmosis fouling control in water reuse

Water Science & Technology Water Supply ◽

10.2166/ws.2010.418 ◽

2010 ◽

Vol 10 (3) ◽

pp. 296-301

Author(s):

Jian-Jun Qin ◽

Maung Htun Oo ◽

Kiran A. Kekre

Keyword(s):

Product Quality ◽

Reverse Osmosis ◽

Water Reuse ◽

High Salinity ◽

Full Scale ◽

Elapse Time ◽

Secondary Effluent ◽

Fouling Control ◽

Membrane Flux ◽

Preliminary Study

We have demonstrated a novel backwash cleaning technique of direct osmosis (DO)-high salinity (HS) for reverse osmosis (RO) fouling control in water reuse. An UF-RO pilot system was continuously (24-h) operated on site with the secondary effluent as the feed over 4 months. The RO plant was run at 75% recovery and at the membrane flux of 17 l m−2 h−1 (LMH) to simulate the full scale NEWater production when DO-HS treatment was conducted once per day and five times per week during the last two months. Permeability of RO membranes as a function of elapse time of the pilot operation was monitored and compared over different durations. Impact of DO-HS treatment on RO product quality in terms of TOC and conductivity was investigated. It was concluded that the DO-HS treatment preliminarily demonstrated a benefit to low RO fouling rate by 2.5–4 times in 30–60 days without interruption on RO operation and impact on RO product quality.

Download Full-text

Advanced Water Treatment of Non-nitrified Secondary Effluent with Tertiary Membrane Bioreactor and Reverse Osmosis Processes

Proceedings of the Water Environment Federation ◽

10.2175/193864713813716426 ◽

2013 ◽

Vol 2013 (8) ◽

pp. 6366-6376

Author(s):

Robert Morton ◽

Thomas Knapp ◽

Nick Smal ◽

Naoko Munakata ◽

Chi-Chung Tang ◽

...

Keyword(s):

Water Treatment ◽

Reverse Osmosis ◽

Membrane Bioreactor ◽

Secondary Effluent

Download Full-text

Adsorption of estrone on nanofiltration and reverse osmosis membranes in water and wastewater treatment

Water Science & Technology ◽

10.2166/wst.2002.0602 ◽

2002 ◽

Vol 46 (4-5) ◽

pp. 265-272 ◽

Cited By ~ 24

Author(s):

L.D. Nghiem ◽

A.I. Schäfer ◽

T.D. Waite

Keyword(s):

Reverse Osmosis ◽

Surface Waters ◽

Natural Waters ◽

Membrane Resistance ◽

Secondary Effluent ◽

Water And Wastewater Treatment ◽

Natural Hormone ◽

Trace Contaminant ◽

Water And Wastewater ◽

Reverse Osmosis Membranes

Adsorption of the trace contaminant estrone, a natural hormone and commonly abundant in surface waters and in treated as well as untreated wastewaters, to eight commercial nanofiltration and reverse osmosis membranes was investigated under well defined conditions. Experiments were conducted in stainless steel stirred cells by spiking trace levels (100 ng.L−1) of estrone into five different matrices, namely MilliQ water, a bicarbonate solution, synthetic natural waters containing natural organics, and secondary effluent. Results show that estrone is adsorbed to the membranes to varying degrees with extent of adsorption influenced by the feedwater composition with different mechanisms of association controlling adsorption to different membrane types. Increase in membrane resistance is typically observed to result in decrease in extent of estrone adsorption.

Download Full-text

Study of different pretreatments for reverse osmosis reclamation of a petrochemical secondary effluent

Journal of Hazardous Materials ◽

10.1016/j.jhazmat.2010.02.020 ◽

2010 ◽

Vol 178 (1-3) ◽

pp. 883-889 ◽

Cited By ~ 20

Author(s):

C. Benito-Alcázar ◽

M.C. Vincent-Vela ◽

J.M. Gozálvez-Zafrilla ◽

J. Lora-García

Keyword(s):

Reverse Osmosis ◽

Secondary Effluent

Download Full-text

Potential of UV/H2O2 oxidation for enhancing the biodegradability of municipal reverse osmosis concentrates

Water Science & Technology ◽

10.2166/wst.2011.465 ◽

2011 ◽

Vol 63 (11) ◽

pp. 2605-2611 ◽

Cited By ~ 10

Author(s):

K. Liu ◽

F. A. Roddick ◽

L. Fan

Keyword(s):

Reverse Osmosis ◽

Oxygen Demand ◽

Complex Compounds ◽

Secondary Effluent ◽

Pseudo First Order Reaction ◽

Fluorescence Excitation ◽

Oxidation Performance ◽

H2o2 Oxidation ◽

Reverse Osmosis Concentrates ◽

Biological Treatment Process

UVC/H2O2 and VUV/H2O2 oxidation processes were evaluated for the degradation of organic pollutants in reverse osmosis concentrate (ROC) produced from a municipal secondary effluent. It was found that the oxidation by UVC/H2O2 and VUV/H2O2 processes could be described as a pseudo first-order reaction. For UVC increased oxidation occurred with increasing H2O2 dosage up to 2 mM above which improvement in oxidation performance decreased. At the same H2O2 dosage, VUV irradiation gave better overall oxidation performance. Compared with UVC/6 mM H2O2, VUV/2 mM H2O2 gave a greater rate of reduction of chemical oxygen demand, but a lower rate for reduction of dissolved organic carbon, suggesting that oxidation of organics by the two methods followed different pathways. The change of absorbance at 254 nm and fluorescence excitation emission matrix spectra of irradiated samples indicated that the large and complex compounds were fragmented rapidly by the •OH, resulting in rapid decolourisation. The biodegradability of the organics in the ROC was increased from 11% to 35% after 1 h treatment by UVC/3 mM H2O2, whereas a greater increase (41%) was obtained with VUV/2 mM H2O2. This increase in biodegradability indicates the potential for employing a subsequent biological treatment process.

Download Full-text

Impact of anti-scalant on fouling of reverse osmosis membranes in reclamation of secondary effluent

Water Science & Technology ◽

10.2166/wst.2009.717 ◽

2009 ◽

Vol 60 (11) ◽

pp. 2767-2774 ◽

Cited By ~ 9

Author(s):

J. J. Qin ◽

M. N. Wai ◽

M. H. Oo ◽

K. A. Kekre ◽

H. Seah

Keyword(s):

Calcium Phosphate ◽

Reverse Osmosis ◽

Membrane Fouling ◽

Pilot Plant ◽

Time Lag ◽

Secondary Effluent ◽

Conventional Activated Sludge ◽

Membrane Flux ◽

Pilot Trials ◽

The Impact

The objective of the study was to evaluate the impact of anti-scalant on fouling of reverse osmosis (RO) membranes in reclamation of secondary effluent which was produced by a conventional activated sludge process at Kranji Water Reclamation Plant with the capacity of 151,000 m3/d. The study was carried out using a RO pilot plant with the capacity of 2.4 m3/h. The RO plant was in 2:1 configuration and was operated at 75% recovery and at membrane flux of 17 l m−2 h−1. Pilot trials were conducted with and without anti-scalant. Compositions of feed and concentrate streams were analyzed and the pilot data were normalized. The results of the study showed that the plant operation was stable during the first few days after stopping dosage of anti-scalant but after 3–6 days of operation the membranes were fouled. The time lag effect of anti-scalant without dosage was not reported previously and could be potentially beneficial to save chemicals. The membrane fouling was more serious at the second stage due to the formation of calcium phosphate scale when the pilot plant was operated without anti-scalant. The flux of fouled membranes could be completely recovered after clean-in-place (CIP) with citric acid, indicating that scaling dominated the fouling of the RO membranes. These findings in the study could be applied to select an appropriate anti-scalant for prevention from formation of calcium phosphate scale in the RO operation.

Download Full-text

Trace Organic Compound Removal from Wastewater Reverse-Osmosis Concentrate by Advanced Oxidation Processes with UV/O3/H2O2

Materials ◽

10.3390/ma13122785 ◽

2020 ◽

Vol 13 (12) ◽

pp. 2785

Author(s):

Aviv Kaplan ◽

Hadas Mamane ◽

Yaal Lester ◽

Dror Avisar

Keyword(s):

Reverse Osmosis ◽

Metal Ion ◽

Advanced Oxidation Processes ◽

Advanced Oxidation ◽

Treated Wastewater ◽

Nutrient Concentrations ◽

Secondary Effluent ◽

Radical Oxidation ◽

Oxidation Processes ◽

Trace Organic

Advanced technologies, such as reverse osmosis (RO), allow the reuse of treated wastewater for direct or indirect potable use. However, even highly efficient RO systems produce ~10–15% highly contaminated concentrate as a byproduct. This wastewater RO concentrate (WWROC) is very rich in metal ions, nutrients, and hard-to-degrade trace organic compounds (TOrCs), such as pharmaceuticals, plasticizers, flame retardants, and detergents, which must be treated before disposal. WWROC could be up to 10 times more concentrated than secondary effluent. We examined the efficiency of several advanced oxidation processes (AOPs) on TOrC removal from a two-stage WWROC matrix in a pilot wastewater-treatment facility. WWROC ozonation or UV irradiation, with H2O2 addition, demonstrated efficient removal of TOrCs, varying between 21% and over 99% degradation, and indicating that radical oxidation (by HO·) is the dominant mechanism. However, AOPs are not sufficient to fully treat the WWROC, and thus, additional procedures are required to decrease metal ion and nutrient concentrations. Further biological treatment post-AOP is also highly important, to eliminate the degradable organic molecules obtained from the AOP.

Download Full-text

Using a membrane bioreactor/reverse osmosis system for indirect potable reuse

Water Science & Technology Water Supply ◽

10.2166/ws.2001.0127 ◽

2001 ◽

Vol 1 (5-6) ◽

pp. 303-313 ◽

Cited By ~ 12

Author(s):

J. Lozier ◽

A. Fernandez

Keyword(s):

Drinking Water ◽

Reverse Osmosis ◽

Membrane Fouling ◽

Membrane Bioreactor ◽

Municipal Wastewater ◽

Secondary Effluent ◽

Potable Reuse ◽

High Calcium ◽

Indirect Potable Reuse ◽

The City

The City of McAllen, Texas, with the assistance of CH2M HILL, has pilot tested an integrated membrane bioreactor (MBR)/reverse osmosis (RO) treatment train to reclaim municipal wastewater to a quality suitable for use as a new drinking water supply in the process called indirect potable reuse. Previous testing by the City (Phase 1) demonstrated the applicability and cost of microfiltration (Memcor and ZeeWeed systems) to enhance the quality of secondary effluent for subsequent treatment by RO and the feasibility of a membrane bioreactor system (ZenoGem) to produce RO feedwater directly from minimally processed sewage. Phase 2 testing, reported on in this paper, is designed to demonstrate reliable operation of MBR/RO treatment for processing screened, degritted sewage and that the effluent from such a train can meet all federal primary and State secondary drinking water regulations and comply with anticipated State requirements for indirect potable reuse. Results show the ZenoGem process to be reliable, require minimal operator attention and maintenance, produce an effluent that can be processed by RO with little fouling and that easily exceeds the City's current effluent discharge requirements relative to BOD, TSS and ammonia. The ZenoGem permeate quality exceeds RO feedwater criteria for turbidity and silt density index and RO system performance confirms minimal membrane fouling by particles. However, the high calcium hardness and phosphate levels in the City's wastewater (and ZenoGem permeate) caused mineral precipitation within the RO system when operated at higher recoveries. Precipitation can be controlled, however, by increased acidification of the RO feedwater.

Download Full-text