Low Suspended Solids Research Articles

Exploring spatial trends and causes in Lake Ontario coastal chemistry: Nutrients and pigments

An ordination approach integrating chemical water quality and biological parameters proved to be an effective method that identified six regional clusters of differing water quality in the nearshore of Lake Ontario. This approach allows for an evaluation of potential factors that contribute to the water quality observed. Creeks and rivers with high dissolved nutrients, low suspended solids, and low biological production as chlorophyll were included in Cluster 1, while Cluster 2 included four bays associated with eutrophic conditions. The shoreside sites along the south shore of Lake Ontario (Cluster 3) had high total phosphorus (TP), chlorophyll, and phycocyanin relative to the offshore and moderate P limitation, suggesting that any P entering these systems from tributaries will stimulate phytoplankton and benthic algal growth. Long Pond and the Genesee River shoreside (Cluster 4) had elevated TP, total suspended solids, and total Kjeldahl nitrogen and high chlorophyll and phycocyanin concentrations. In general, offshore waters and the eastern nearshore and embayments of Lake Ontario (Clusters 5 and 6) had relatively low P, N, chlorophyll, and phycocyanin levels and were the most severely limited for P (N/P = molar ratio 82). Phosphorus loads to embayments and perhaps to the nearshore may be creating regional areas where N-limitation is likely, which tends to favor the growth of Cyanobacteria and may be associated with hepatotoxin production. From a management perspective, such analyses identify regions stressed by nutrients and provide possible causal relationships enabling the targeting of regions of the lake and its watershed for remediation.

Water chemistry and endangered white-clawed Crayfish: a literature review and field study of water chemistry association inAustropotamobius pallipes

Populations of the endangered white-clawed crayfish (Austropotamobius pallipes) have rapidly declined in distribution and density in recent decades as a result of invasive crayfish, disease and habitat degradation. The species is thought to be particularly sensitive to water chemistry, and has been proposed as a bio-indicator of water quality. Here we detail the results of a systematic review of the literature regarding the chemistry of waterbodies inhabited by white-clawed crayfish, along with a wide-scale field study of the chemistry of crayfish-inhabited waterbodies in the UK. We use these data to examine potentially significant variables influencing crayfish distribution. Several variables appear to have thresholds that affect crayfish distribution; crayfish presence was associated with high dissolved oxygen, low conductivity, ammonium, sodium, and phosphate, and to a lesser extent low sulphate, nitrate, and total suspended solids. Some variables (magnesium, potassium, sodium, sulphate, nitrate, and total suspended solids) may be tolerated at moderate to high concentrations in isolation (indicated by the presence of some populations in high levels of these variables), but suites of chemical conditions may act synergistically in situ and must be considered together. Recent efforts to conserve white-clawed crayfish have included relocations to Ark Sites; novel protected habitats with reduced risk of the introduction of disease, invasive crayfish and habitat degradation. We use our findings to propose the first detailed guidelines for common water chemistry variables of potential Ark Sites for the conservation of the species throughout its European range.

Sewage Treatment Systems: SBR and MBBR

The analysis and evaluation of the performance of sequential batch reactor (SBR) and moving bed biofilm reactor (MBBR) wastewater treatment technology operated under cold waste water conditions were done with the aim to investigate the nitrogen and phosphorous removal, sludge quality aspects and energy efficiency. Many wastewater treatment processes are temperature dependent. In some cases water temperature is below 25°C for most of the time. Moreover more stringent effluent requirements are expected to be implemented, as negative influence of nutrients becomes even more apparent. Therefore MBBR is preferred over SBR. MBBRs have significantly lower suspended solids production and hence the membrane is exposed to lower solids concentrations leading to reduced fouling potential. By comparison the MBBR technology does not require tertiary filtration and polymer addition to meet the standards for suspended solids and turbidity. Despite the potential benefits of the MBBR technology there has only been limited study of this configuration and more research is required to assess various operational conditions for this system in order to develop this process and increase its acceptance for wastewater treatment.

Performance of a temperate-zone channel catfish biofloc technology production system during winter

Channel catfish (Ictalurus punctatus) have been grown successfully in an outdoor biofloc technology production system. Outdoor biofloc production systems in the tropics are operated year-round, whereas the channel catfish studies were conducted only during the growing season and biofloc production tanks were harvested and idled for the winter. If an outdoor biofloc production system is to be adopted by farmers at temperate latitudes, then data gaps related to system and fish performance over the winter must be addressed. The present study was conducted to address these data gaps for channel catfish culture. Waters from a recently completed biofloc production experiment that contained low (153.3mg/L) and high (790.0mg/L) total suspended solids were retained for this study. Three 15.7-m3 tanks per water type each were stocked (8kg/m3) with market size channel catfish from that same study for a 152-day study from November to April. Mean chlorophyll a concentrations were similar in both treatments during the first 55 days, after which treatments diverged and chlorophyll a concentration increased linearly (P<0.001, R2=0.721) to a mean final concentration of 2251.7mg/m3 in the low solids treatment. Ammonia from ammonium chloride spikes (1.25–1.5mg TAN) added on three occasions during the experiment was biotransformed completely, putatively by algal uptake and nitrification. Ammonia biotransformation rate was linearly related to mean water temperature in the high solids (P<0.001, R2=0.920) and low solids (P=0.002, R2=0.761) treatments. Catfish survival through the winter was high (99.75%) in biofloc tanks and did not differ significantly between treatments. Net fish yield did not differ significantly between treatments. However, net fish yields were 1–4% less than initial fish biomasses. Water in the biofloc production tanks appeared to retain through the winter the ability to biotransform ammonia regardless of whether phytoplankton or suspended solids predominate and despite sustained input of ammonia-nitrogen. Having an active biofloc in the spring obviates the start-up time required to establish a new, fully functional biofloc and the associated TAN and nitrite spikes.

Evaluation of full-scale vertical peat biofilters for treatment of septic tank effluents

The performances of single-pass vertically loaded fibrous peat biofilters treating septic tank wastewater from a single household (pe 6) and a small rural housing estate (pe ~100) are compared. Both systems achieved >90% BOD removal and consistently low suspended solids <11 mg L−1. Pathogen removal was generally >95% but inconsistent. Nitrification was linked to temperature with removal rates seasonal (50–98%) with no denitrification; this resulted in final effluents with either high NH4 or NO3 concentrations, both unsuitable for discharge to surface or ground waters. Phosphorus removal was generally poor. The filters responded poorly to sudden increases in hydraulic loading, causing a reduction in BOD removal in particular. Subsequent soil treatment of effluents after filtration caused a small decrease in both physicochemical and microbial quality. Single-pass vertical peat filters cannot meet the more stringent EU nutrient and microbial standards required for on-site treatment without tertiary treatment to ensure full compliance.

Dissolved air flotation separation for pretreatment of membrane bioreactor in domestic wastewater treatment

Research Article| July 25 2014 Dissolved air flotation separation for pretreatment of membrane bioreactor in domestic wastewater treatment Youngsuk Kim; Youngsuk Kim 1Civil and Environmental Engineering, University of Ulsan, Ulsan City, 680-749 Korea3National Institute of Environmental Research, Environmental Infrastructure Department, Drinking Water and Sewerage Research Division, Seoul, Korea Search for other works by this author on: This Site PubMed Google Scholar Donghwan Choi; Donghwan Choi 1Civil and Environmental Engineering, University of Ulsan, Ulsan City, 680-749 Korea Search for other works by this author on: This Site PubMed Google Scholar Meiying Cui; Meiying Cui 1Civil and Environmental Engineering, University of Ulsan, Ulsan City, 680-749 Korea Search for other works by this author on: This Site PubMed Google Scholar Jeonyoul Lee; Jeonyoul Lee 1Civil and Environmental Engineering, University of Ulsan, Ulsan City, 680-749 Korea Search for other works by this author on: This Site PubMed Google Scholar Bunsu Kim; Bunsu Kim 1Civil and Environmental Engineering, University of Ulsan, Ulsan City, 680-749 Korea Search for other works by this author on: This Site PubMed Google Scholar Kyungho Park; Kyungho Park 1Civil and Environmental Engineering, University of Ulsan, Ulsan City, 680-749 Korea Search for other works by this author on: This Site PubMed Google Scholar Hyungmok Jung; Hyungmok Jung 2Samsung C & T. Civil Work Dept., Hamyang-Sungsan Expressway Section 6, 680-701 Korea Search for other works by this author on: This Site PubMed Google Scholar Byoungho Lee Byoungho Lee 1Civil and Environmental Engineering, University of Ulsan, Ulsan City, 680-749 Korea E-mail: bhlee@ulsan.ac.kr Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2015) 64 (2): 186–193. https://doi.org/10.2166/aqua.2014.003 Article history Received: December 12 2012 Accepted: June 30 2014 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share MailTo Twitter LinkedIn Tools Icon Tools Cite Icon Cite Permissions Search Site Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsThis Journal Search Advanced Search Citation Youngsuk Kim, Donghwan Choi, Meiying Cui, Jeonyoul Lee, Bunsu Kim, Kyungho Park, Hyungmok Jung, Byoungho Lee; Dissolved air flotation separation for pretreatment of membrane bioreactor in domestic wastewater treatment. Journal of Water Supply: Research and Technology-Aqua 1 March 2015; 64 (2): 186–193. doi: https://doi.org/10.2166/aqua.2014.003 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Due to requiring higher water quality standards over time, new technologies are being employed for wastewater treatment. Dissolved air flotation (DAF) and membrane bioreactor (MBR) technologies are widely employed as new technologies in wastewater treatment. DAF is used due to its excellent separation capability of suspended solids as well as oily material. MBR is used because it may provide a high level of mixed liquor suspended solids in a biological system and excellent separation capability too. In the investigation, separation by DAF, without addition of coagulant, could remove chemical oxygen demand by potassium dicromate (CODcr) up to over 70%, biochemical oxygen demand (BOD5) 73%, suspended solids (SS) 83%, total nitrogen (T-N) 55%, and total phosphorus (T-P) 65% in influent of municipal wastewater. Average overall removal rates of water quality parameters by the DAF-MBR system were very high such as CODcr 95.9%, BOD5 99.7%, chemical oxygen demand by potassium permanganate) 93.6%, T-N 69.8%, NH4-N 98.5%, T-P 78.2%, and SS 99.5%, which satisfy effluent water quality standards. Membrane separation in the MBR system produced a very low SS concentration of 1.27 mg/ℓ in the final effluent. It was proven that DAF separation is an excellent technology for pretreatment of wastewater treatment, especially for an MBR system. DAF, MBR, membrane fouling, pretreatment, wastewater © IWA Publishing 2015 You do not currently have access to this content.

Lagrangian analysis of the transport and processing of agricultural runoff in the lower Maumee River and Maumee Bay

Lagrangian analyses is used to evaluate the processing of nutrients and sediments during storm runoff events as water moved from the Maumee River loading station at Waterville, OH through the lower river, Maumee Bay and into Lake Erie's western basin. Chemical signatures of storm water at Waterville were used in combination with frequent collections of water at transects along the flow paths to evaluate processing. These signatures consisted of the contrasting chemographs of conservative parameters (chloride and sulfate), dissolved nutrients (dissolved reactive phosphorus (DRP) and nitrate) and particulate substances (suspended solids (SS) and particulate phosphorus (PP)). During low flow, sharp drops in concentrations of chloride and sulfate indicated that mixing zones between river water and bay/lake water occurred at the river mouth. During high flows, the location of the mixing zone between riverine and bay/lake water was indicated by the margin of storm-event sediment plumes, with larger storms extending further into the lake. Steep concentration gradients of DRP and nitrate between high storm water concentrations and low bay/lake water concentrations were also present at the plume margin. The large areas of storm water inside the plume margin contained high DRP and nitrate concentrations but relatively low SS and PP concentrations, due to SS and PP deposition along the flow paths. Because this deposition occurred in water with high DRP concentrations, little of the bioavailable PP was likely to have been released prior to deposition. This storm runoff water provides excellent media for algal growth.

Treatment of tunnel wash water and implications for its disposal

The use of road tunnels in urban areas creates water pollution problems, since the tunnels must be frequently cleaned for traffic safety reasons. The washing generates extensive volumes of highly polluted water, for example, more than fivefold higher concentrations of suspended solids compared to highway runoff. The pollutants in the wash water have an affinity for particulate material, so sedimentation should be a viable treatment option. In this study, 12 in situ sedimentation trials were carried out on tunnel wash water, with and without addition of chemical flocculent. Initial suspended solids concentration ranged from 804 to 9,690 mg/L. With sedimentation times of less than 24 hours and use of a chemical flocculent, it was possible to reach low concentrations of suspended solids (<15 mg/L), PAH (<0.1 μg/L), As (<1.0 μg/L), Cd (<0.05 μg/L), Hg (<0.02 μg/L), Fe (<200 μg/L), Ni (<8 μg/L), Pb (<0.5 μg/L), Zn (<60 μg/L) and Cr (<8 μg/L). Acute Microtox(®) toxicity, mainly attributed to detergents used for the tunnel wash, decreased significantly at low suspended solids concentrations after sedimentation using a flocculent. The tunnel wash water did not inhibit nitrification. The treated water should be suitable for discharge into recipient waters or a wastewater treatment plant.

Probabilistic prediction of cyanobacteria abundance in a Korean reservoir using a Bayesian Poisson model

AbstractThere have been increasing reports of harmful algal blooms (HABs) worldwide. However, the factors that influence cyanobacteria dominance and HAB formation can be site‐specific and idiosyncratic, making prediction challenging. The drivers of cyanobacteria blooms in Lake Paldang, South Korea, the summer climate of which is strongly affected by the East Asian monsoon, may differ from those in well‐studied North American lakes. Using the observational data sampled during the growing season in 2007–2011, a Bayesian hurdle Poisson model was developed to predict cyanobacteria abundance in the lake. The model allowed cyanobacteria absence (zero count) and nonzero cyanobacteria counts to be modeled as functions of different environmental factors. The model predictions demonstrated that the principal factor that determines the success of cyanobacteria was temperature. Combined with high temperature, increased residence time indicated by low outflow rates appeared to increase the probability of cyanobacteria occurrence. A stable water column, represented by low suspended solids, and high temperature were the requirements for high abundance of cyanobacteria. Our model results had management implications; the model can be used to forecast cyanobacteria watch or alert levels probabilistically and develop mitigation strategies of cyanobacteria blooms.

Lignite-Derived Humic Substances for Treatment of Acid Mine Drainage

Abstract Acid mine drainage (AMD) generated by some coal mines in New Zealand is currently neutralized by the addition of alkaline reagents, triggering the precipitation of dissolved metals as insoluble hydroxides. This study investigated the addition of lignite-derived humic substances (HSs) before, during, and after neutralization of AMD based on two Stockton Mine treatment scenarios: the Blackwater Treatment Plant (BTP) and the Mangatini Stream-Sump (MSS). Supernatant samples collected during the sedimentation period were analyzed for basic water quality parameters: turbidity and suspended solids (SSs). The BTP scenario used calcium hydroxide [Ca(OH)2] neutralization, resulting in low supernatant turbidity (<2 NTU, nephelometric turbidity units) and SSs (<5 mg/L) regardless of the HS addition sequence. The MSS scenario used calcium carbonate (CaCO3) neutralization, and showed HS dosing enhanced flocculation and sedimentation of residual CaCO3 SSs when added after neutralization, resulting in up to 75% ...

Advanced characterization of fouling in membrane coupled with upflow anaerobic sludge blanket process

In this study, an advanced process based on the use of ultrafiltration hollow fibre membranes immersed in the supernatant of an upflow anaerobic sludge blanket bioreactor (MUASB) and operated under low permeate flux was proposed. Process sustainability was assessed under different operating conditions: membranes were immersed either in the supernatant or in the biomass bulk and operated under various permeate fluxes. Additionally, temporal investigation was also proposed through the advanced characterization of fouling behaviour by systematic fractionation (based on level of reversibility) and analysis by liquid chromatography–organic carbon detector. Among the various suspended solids (SS) concentrations in supernatant (10, 25, 100, and 400 mg L−1) and in biomass bulk (6500 mg L−1), higher fouling levels were observed under low SS concentrations. However, more easily reversible fouling was obtained under MUASB conditions, demonstrating potential long-term sustainability. Results of long-term operation indicated that an increase of flux leads to larger amounts of SS participating in irreversible fouling and higher irreversibility. Temporal change in fouling characteristics revealed that the most easily removable fouling layer (i.e. cake), and its relative fraction of SS, were the two main factors impacting on the overall hydraulic performance. Additionally, the development of microbial population on the membrane surface was closely related to the proteins content and the overall hydraulic resistance. Polysaccharides and other dissolved organic matters (humic substances, building blocks, and low molecular weight compounds) presented low effect on membrane fouling.

The susceptibility of cladocerans in North Andean Patagonian lakes to volcanic ashes

Summary Explosive volcanic eruptions are one of the few natural phenomena that can produce global catastrophic effects. On 4 June 2011, an eruption in the Puyehue volcanic complex (40°35′S, 72°06′W, Chile) discharged massive amounts of ash and pumice into the surrounding landscape in Argentina (North Andean Patagonia). The ejected material affected nearby aquatic environments, producing an increase in total suspended solids. We combined field data and laboratory experiment data to determine the effect of the volcanic ashes suspended in the water column on cladoceran populations. During the summer of 2011–2012 (6 months after the eruption), zooplankton populations in these lakes decreased, mainly due to the disappearance of cladocerans. This decrease in zooplankton was not caused by food shortage; chlorophyll a concentrations in the lakes were higher than in previous years or in the following season, and no change in phytoplankton size was observed. By the following summer (2013), 18 months after the eruption, a recovery of cladoceran populations was observed, with a concomitant decrease in total suspended solids. We performed a life‐table experiment, examining Daphnia commutata survival and fecundity at a series of ash concentrations. Ash concentrations of 2, 3, 5 and 8 mg L−1 negatively affected survival and fecundity. Populations exposed to 8 mg L−1 of ash cannot persist; these organisms fail to produce offspring because they die before reaching reproductive age. We conclude that the disappearance of cladocerans was due to the presence of ash. As the sedimentation process occurs, ash concentrations decrease, favouring population recovery, as observed the following summer. When the lakes recovered their original transparency with low total suspended solids values, the cladoceran populations also returned to their historical abundances. Previous data on other explosive volcanic eruptions and the present data indicate that immediately after ash fall, the zooplankton suffer reduced abundance, particularly of non‐selective filter feeders such as daphnids. However, recovery of zooplankton population growth can be expected within a few years.

On-site treatment of textile yarn dyeing effluents using an integrated biological–chemical oxidation process

This paper reports the results of the treatment of a yarn dyeing effluent using an integrated biological–chemical oxidation process. In particular, the biological unit was based on a sequencing batch biofilter granular sludge reactor (SBBGR), while the chemical treatment consisted of an ozonation step. Biological treatment alone was first performed as a reference for comparison. While biological treatment did not produce an effluent for direct discharge, the integrated process assured good treatment results, with satisfactory removal of chemical oxygen demand (up to 89.8 %), total nitrogen (up to 88.2 %), surfactants (up to 90.7 %) and colour (up to 99 %), with an ozone dose of 110 mg of ozone per litre of wastewater. Biomass characterization by fluorescence in situ hybridization has revealed that filamentous bacteria represented about 20 % of biomass (coherently with high sludge volume index values); thanks to its special design, SBBGR guaranteed, however, stable treatment performances and low effluent suspended solids concentrations, while conventional activated sludge systems suffer from sludge bulking and even treatment failure in such a condition. Furthermore, biomass characterization has evidenced the presence of a shortcut nitrification–denitrification process.

Factors influencing urease driven struvite precipitation

The concern about phosphorus depletion is driving more efficient phosphorus use and recycling. In this context the precipitation of phosphate as struvite from wastewaters has recently gained considerable traction. This study investigates the influence of different parameters on the ureolytic phosphate precipitation (pH increase by means of urease activity). Wastewater with a high phosphate concentration (>50mgL−1 PO4–P) and low volatile suspended solids (⩽3.0gL−1 VSS) resulted in a high phosphate removal efficiency (87%) and struvite crystals that could be separated from the sludge. An increase in ionic strength resulted in a decrease in ureolytic activity. An increase in Mg2+:PO43- molar ratio increases the degree of supersaturation with respect to struvite formation, which enhances the phosphate removal. Above a Mg2+:PO43- molar ratio of 3, additional Mg2+ dosage did not significantly affect the phosphate removal efficiency. Wastewater containing low phosphate concentrations (<50mgL−1 PO4–P), needed disproportionally large chemical additions and are thus not economically rewarding. For those wastewaters the presence of calcium interfered with the struvite precipitation rendering the precipitation of calcium phosphate a better option.

Membrane filtration of the liquid fraction from a solid–liquid separator for swine manure using a cationic polymer as flocculating agent

The liquid fraction from a solid–liquid separator for swine manure, which used a cationic polymer to promote particle flocculation, was processed by one nanofiltration and two reverse osmosis spiral-wound membranes. Eight different liquid fraction batches (750 to 1750 L) were concentrated at volumetric concentration ratios (VCRs, initial to final volumes) ranging from 2.3 to 4.2. Membrane fouling intensity was highly variable, as water flux recovery after concentration cycles ranged from 13% to 88%. The most severe fouling was caused by a liquid fraction that had relatively low suspended solids (SS) (774 mg/L) and was concentrated at a low VCR of 2.6. Raw manure collected the same day also contained low SS, suggesting that fewer sites were available for polymer adsorption and thus more polymer remained in the liquid. However, because of the high opacity of the samples, residual polymer could not be detected in any feed or concentrate samples. Fouling was not totally irreversible as over 97% of membrane flux could be recovered by cleaning with acidic and alkaline solutions. Further tests with spiked liquid fractions indicated that fouling due to residual polymer in solution started to occur at a polymer concentration of 3 and 11 mg/L in initial and concentrated effluents, respectively. If a cationic polymer is used to pretreat manure, the amount of added polymer would have to be closely related to SS content as opposed to manure volume, in order to leave very little residual polymer in solution.

Treatment of a chocolate industry wastewater in a pilot-scale low-temperature UASB reactor operated at short hydraulic and sludge retention time

The aim of this work was to evaluate the performance of a 244-L pilot-scale upflow anaerobic sludge blanket (UASB) reactor during the treatment of chocolate-processing industry wastewater under low-temperature conditions (18 ± 0.6 °C) for approximately 250 d. The applied organic loading rate (OLR) was varied between 4 and 7 kg/m(3)/d by varying the influent soluble chemical oxygen demand (CODsol), while keeping the hydraulic retention time constant (6.4 ± 0.3 h). The CODsol removal efficiency was low (59-78%). The measured biogas production increased from 240 ± 54 to 431 ± 61 L/d during the experiments. A significant linear correlation between the measured biogas production and removed OLR indicated that 81.69 L of biogas were produced per kg/m(3) of CODsol removed. Low average reactor volatile suspended solids (VSS) (2,700-4,800 mg/L) and high effluent VSS (177-313 mg/L) were derived in a short sludge retention time (SRT) (4.9 d). The calculated SRT was shorter than those reported in the literature, but did not affect the reactor's performance. Average sludge yield was 0.20 kg-VSS/kg-CODsol. The low-temperature anaerobic treatment was a good option for the pre-treatment of chocolate-processing industry wastewater.

The Role of Biofilm in Clogging Process in Vertical Flow Constructed WeTland

This article explores the cause of substrate clogging in the absence of suspended solids or very low suspended solids (<<10mg/L, Water quality integrated wastewater discharge standard (GB189918-2002) level 1A emissions standards) in the influent during the operation process. Both the growth and detachment of biofilm were found to play positive roles in the clogging process under commonly used hydraulic loading in vertical constructed wetland. In addition, the existence of the biofilm enabled the suspended solids to combine much easier, which accelerated the settlement and interception of the solids. The biofilm secreted extracellular polysaccharides, which added to the adhesion property of the substrate. Thus, more solids were captured, and the occurrence of clogging was accelerated. Finally, the conceivable clogging process mainly caused by biofilm was conceptually described. However, the quantitative effects of the biofillm on clogging are still desirable to be studied.

Two-stage biofilm-MBR for nitrogen removal and enhanced membrane performance

A two-stage biofilm-membrane bioreactor (MBR) was developed in this study. High total nitrogen removal (maximum: 81.4% with recycle ratio = 3.5) was observed by recycling the suspension liquid between an anaerobic FBBR and an aerobic MBBR. Very low (less than 60 mg/L) suspended solids was kept in the membrane unit, which could improve the membrane filtration performance. Membrane fouling was further reduced by increasing the recycle ratio. When influent organic load increased, the membrane fouling rate increased, coupling with higher FCOD and suspended solids (SS) values in the feed solution around the membrane.

Evaluating the efficiency of different microfiltration and ultrafiltration membranes used as pretreatment for Red Sea water reverse osmosis desalination

Conventional processes are widely used as pretreatment for reverse osmosis (RO) desalination technology since its development. However, these processes require a large footprint and have some limitation issues such as difficulty to maintain a consistent silt density index, coagulation control at low total suspended solids, and management of higher waste sludge. Recently, there has been a rapid growth in the use of low-pressure membranes as pretreatment for RO systems replacing the conventional processes. However, despite the numerous advantages of using this integrated membrane system mainly providing good and stable water quality to RO membranes, many issues have to be addressed. The primary limitation is membrane fouling which reduces the permeate flux; therefore, higher pumping intensity is required to maintain a consistent volume of product. This paper aims to optimize the permeation flux and cleaning frequency by providing high permeate quality. Different low-pressure polyethersulfone membranes with different pore sizes ranging from 0.1μm to 50 kDa were tested. Eight different filtration configurations have been applied including the variation of coagulant doses aiming to control membrane fouling. Results showed that all the configurations with/without coagulation, provided permeate with excellent water quality which improves the stability of RO performance. However, more stable fluxes with less-energy consumption were achieved by using the 0.1μm and 100 kDa membranes with 1 mg/L FeCl3 coagulation. The use of UF membranes, having tight pores, without coagulation also proved to be an excellent option for Red Sea water RO pretreatment.

Treatment of wet peat mining process water with acrotelm peat

Mechanical dewatering of wet mined peat produced peat mining process water (PMPW) with low pH (5.49) and high total suspended solids (TSS 432 mg L−1), Al (1.39 mg L−1), Fe (4.36 mg L−1), Hg (37.1 ng L−1), MeHg (0.485 ng L−1), Zn (55 μg L−1), total nitrogen (TN 7.92 mg L−1), total phosphorus (TP 303 μg L−1) and true colour (532 TCU). High removal efficiencies were calculated for acrotelm peat filters (mesocosms) used to treat PMPW (TSS 45–83%; particulate organic carbon (POC) 47–89%; metals 53–100%; TN 85%; TP 81%), though final mesocosm leachate concentrations did not all achieve Canadian Water Quality Guidelines. In one study, mesocosm leachate had higher colour and dissolved organic carbon (DOC) concentrations than PMPW. Our mesocosm studies suggest an initial reduction in PMPW solids be considered by industry before peatlands are used as treatment systems.