High Concentrations Of Suspended Solids Research Articles

Optimization of turbidity removal by coagulation and flocculation process from synthetic stone cutting wastewater

Cutting industries produce large quantities of wastewaters with the high content of suspended solids and turbidity. The treatments of these wastewaters are important in preventing the environmental pollution. This study aimed to optimize the use of coagulation and flocculation process by the response surface methodology (RSM) method as an effective method for the abatement of turbidity-related challenges of such wastewater using coagulants of Alum and polyaluminum chloride. This study is an analytical-applied. The synthetic wastewater with a turbidity of 170 ± 2 NTU at each stage of the jar test was used. The effect of Alum and PAC application was evaluated and compared each other as a function of settling time (40–140 min), pH (2–8), speed (20–60 rpm), and the coagulant dose (0–200 mg/l). In this study, the central composite design (CCD) was utilized to experimental design, modeling, and optimization of the turbidity removal from a stone cutting wastewater. A total of 33 experiments were designed for each coagulant. Results showed that the optimal conditions for turbidity removal were settling time, initial pH, speed, coagulant dosage, 40.98, 7.47, 55.44, 163.56–56.62, 7.93, 34.55, and 199.53 for Alum and PAC, respectively. Under these optimal values of process parameters, the dye removal efficiency of 100% and 98.84% was observed for Alum and PAC, respectively. The sum of squares model showed that the quadratic model is the best option for empirical data with the highest correlation coefficient (R2 of 0.99 and 0.98 for Alum and PAC, respectively.) and P value < 0.0001 for both models. The models can adequately describe the prominent behavior of turbidity removal process. Although a high turbidity removal was observed for application of the both coagulants, in real-scale selection, each of them is related to the operator conditions. Moreover, further investigations should be considered to generalization of this work results to the real-stone cutting wastewater. Besides, the TSS challenge of such wastewater should be solved before scaling-up the results.

Removals of pharmaceutical compounds at different sludge particle size fractions in membrane bioreactors operated under different solid retention times.

Removals of 10 pharmaceutical compounds by microbial sludge in membrane bioreactors (MBR) operated under infinite and limited solid retention time (SRT) were investigated. High removal (>80%) of DCF, TMP, NPX, IBP, and TCS were achieved but CBZ removals were low (<20%). The residual pharmaceutical compounds leftover from the biodegradation in different sludge particle size fractions was quantified through physical separation and filtration in series. The results revealed that hydrophobic compounds were mainly adsorbed onto the coarse particles (>0.45μm) where majority of adsorption site was available. Meanwhile, hydrophilic and moderate hydrophobic compounds were less associated with particles and they were retained in fine particles and gel-like substances (1 kDa-0.45μm). Most of the studied pharmaceutical compounds associated with fine particles and gel-like substances was subsequently rejected by membrane filtration in the MBRs. The operation of the MBR at high mixed liquor suspended solids concentration under long sludge age conditions could enhance the removals of pharmaceutical compounds through increased adsorption site on the sludge particles.

Energy generation in the treatment of effluent from washing of municipal solid waste collection trucks

The washing of vehicles used to collect Municipal Solid Waste (MSW) requires 400–500 L of water for each vehicle, producing effluent with characteristics similar to the leachate from young sanitary landfills. The treatment process commonly used for this type of effluent is coagulation/flocculation. In this study, effluents from three sites were submitted to physicochemical treatment alone or combined with anaerobic biological treatment. Physicochemical treatment has better results with effluents with high total suspended solids (TSS) content. For effluents with low TSS concentrations, this treatment has high turbidity removal but low chemical oxygen demand (COD) removal. The anaerobic biodegradability and the methane generation potential from raw effluents or after physicochemical treatment were evaluated with and without nutritional supplementation. The effluent after physicochemical treatment does not require nutritional supplementation, obtaining 92% COD removal (final COD of 168 mg/L) and specific methane production of 150.6 mL methane (STP)/g CODremoved. A comparison of operational cost between the physicochemical and anaerobic biological processes for treating 20 m3/day of effluent showed that the latter, in addition to presenting low cost, can generate up to 13.5 kWh/day for the MSW collecting company.

A Study on the Treatment of Construction Wastewater Using Multi-Stage Settlement

Wastewater generated from tunnel excavation and construction site is constantly generating complaints and disputes due to environmental pollution problem caused by turbid water in a river near a construction site. Therefore, there is a lot of research on the processing method. In this study, a continuous multistage (3-stage) flocculation and precipitation reactor was developed to treat the construction wastewater with high concentration of suspended solids and strong alkalinity. This R & D technology can carry out mixing, coagulation, sedimentation and concentration in one reaction tank. And has a high response to the deterioration of the wastewater which is continuously changing. This technology is an economical and efficient technology for treating construction wastewater without the need for a separate sewer facility. In order to verify the performance of the equipment, we collected and analyzed the actual construction waste water. As a result, SS 88.31%, Turbidity 81.14% and CODcr 54.17% were removed. Therefore, it is expected that the use of this technology will reduce water treatment costs and increase treatment efficiency. This technology can reduce the facility cost and the required site area compared to the existing coagulation sedimentation technology. It is also possible to remove suspended matters with high efficiency without using coagulant and coagulant.

Factors controlling sediment and nutrient fluxes in a small microtidal salt marsh within the Venice Lagoon

Coastal salt marshes are among the Earth's most productive ecosystems and provide a number of ecosystem services. Water quality regulation by storing, transforming and releasing nutrients, organic matter and suspended sediment is recognized as one of the most important functions of salt marshes. The self-purification capacity of intertidal ecosystems contributes to mitigating nutrient inputs, acting as a buffer zone between watersheds and coastal waters, especially in relation to climate change and the increasing frequency of impulsive extreme events. Understanding sediment and nutrient fluxes and assessing the mechanisms that control them are valuable for the preservation and future restoration of salt marshes and for enhancing their effectiveness in providing water quality regulation services.To investigate the main driving factors in microtidal environments, changes in suspended sediment and nutrient concentrations were measured during several tidal cycles in a small microtidal reconstructed salt marsh in the Venice Lagoon, which was selected as the experimental site. The tidal amplitude, nutrients and total suspended solid concentrations were measured during 6 tidal cycles between September 2011 and October 2013. The water discharge was derived by forcing the hydrodynamic MIKE-DHI numerical model with the measured tidal levels. Fluxes were assessed by coupling field data with the calculated discharges. The salt marsh filtering function was related to the inflow matter concentrations and tidal amplitude. When high suspended solid and nutrient concentrations enter the salt marsh, accumulation processes prevail on release. In contrast, in the case of low concentrations and high tidal excursion, the salt marsh functions as a nutrient and sediment source. During all campaigns, the nitrogen removal function was more effective within the intertidal vegetated areas. Sediment release was the dominant process in the outermost creek, whereas sedimentation prevailed in the inner area of the salt marsh because of the attenuation of hydrodynamic forcing during tide propagation.

Экологические аспекты наличия аномально высоких концентраций взвешенных веществ в макроприливных устьях рек Арктической зоны

Экологические аспекты наличия аномально высоких концентраций взвешенных веществ в макроприливных устьях рек Арктической зоны

The Valorization of Ammonia in Manure Digestate by Means of Alternative Stripping Reactors

The proper recovery of resources such as nitrogen and phosphorus present in the manure from intensive livestock farming is essential in order to allow environmental sustainable zootechny especially in densely populated areas where these activities are historically prevalent. The experiences at full-scale established that the ammonia stripping allows recovery from 35% to 50% of nitrogen depending on the type of substrate treated with anaerobic digestion and on the nitrogen content/form in the digestate. This study focuses on the ammonia stripping on digestate derived from anaerobic digestion of livestock manure and corn silage. Two different full-scale plants are studied including a packed column and an air bubble reactor without filling material with the aim to reduce fouling issues due to the content of suspended solids in digestate. The main results suggest that the use of an air bubble reactor could treat digestate with high concentration of suspended solids. A deeper study based on a two-level factorial experiment highlights that the temperature is an important parameter that influences the ammonia removal yields. Thus, a proper management of available thermal energy is very important.

Melting of clean and debris‐rich ice differentially affect nutrients, dissolved organic matter and bacteria respiration in the early ontogeny of the newly formed proglacial Ventisquero Negro Lake (Patagonia Argentina)

Abstract Climate change affects glaciers all over the world causing glacial recession with the formation of new lakes. Glaciers of Mount Tronador (41° S, Patagonia, Argentina) underwent an increase of more than 200 m in the equilibrium‐line altitude (ELA), from 1994 to 2016. The proglacial Lake Ventisquero Negro showed a continuous increase in lake surface area since 2009, when a glacial outburst flood (GLOF) occurred. The Ventisquero Negro glacier is a debris‐covered glacier located below the timberline; thus, the lake receives meltwater from both clean and debris‐rich ice. This study analyses the proglacial lake after the GLOF event, particularly the nutrient content, dissolved organic matter and bacterial respiration. Our main hypothesis was that the melting of debris‐rich and clean ice would differentially affect nutrient inputs and bacterial respiration in the early ontogeny of the lake. Sampling was conducted in austral spring–summer seasons (2012 to 2016) following the GLOF event. We carried out bacterial respiration experiments with lake water and two treatments enriched with clean or debris‐rich ice from the glacier. Additionally, we carried out an another enrichment experiment with phosphate‐P and glucose‐C alone or in combination. The lake exhibited high turbidity levels due to a high concentration of suspended solids. Vertical light profiles showed that almost the entire water column was aphotic. Phosphorus (P) concentration was high and was positively related to total suspended solids. Accordingly, P concentration was higher in debris‐rich than in clean ice. However, the dissolved organic carbon concentrations in the lake were found to remain relatively constant through time (less than 50 μmol/L). Analysing fluorescent excitation–emission matrices, we determined that the dissolved organic matter is very simple with only two peaks, one corresponding to protein‐like compounds (C1) and the other to humic‐like compounds (C2), coming from clean ice and debris‐rich ice, respectively. C1 was present in all samples, while C2 was comparatively more important during summer, coinciding with higher temperatures and melting. This study supports the hypothesis that melting of clean and debris‐rich ice would affect DOM and P input at early stages of a proglacial lake formed by the recession of a debris‐covered glacier. Bacterial respiration was observed to be positively affected by debris‐rich ice melting and to be P limited. Thus, P is a major controlling factor for carbon dynamics in a newly formed proglacial lake.

Membrane-based pretreatment to mitigate variations in desalination plants.

The main source of potable water in high water-stress areas is commonly produced in brackish and seawater desalination plants. Owing to the presence of high concentration of suspended solids, organic matter and colloidal particles in raw water, pretreatment processes are needed for a stable operation of desalination plants. A submerged membrane ultrafiltration pilot plant has been operated as pretreatment of complex brackish surface water to study the filtration performance. The results show the membrane performance, chemical reagent requirements, water quality and cleaning procedures efficiency of an ultrafiltration pilot plant used as pretreatment for a reverse osmosis system. Alternative chemical cleaning procedures have been satisfactorily implemented, which maximize permeability recovery and allow a stable operation.

Application of extended full resolution MERIS imagery to assist coastal management of the area adjacent to the Guadalquivir estuary

High concentrations of suspended solids in coastal waters directly affect numerous processes. In the case of the marine region influenced by the Guadalquivir estuary, turbidity is one of the primary factors affecting this complex ecosystem and its adjacent coastal region. Ten-year (2002–2012) ocean color observations from the MEdium Resolution Imaging Spectrometer (MERIS) at 300 m are used to assess the variability of turbidity and chlorophyll-a concentration (Chl) in this region. The combination of high-frequency data from automated sensors in addition to synoptic imagery results in an excellent complement to better study water quality parameters. Turbidity plumes detected using the backscattering characteristics of the surface waters with Remote Sensing Reflectance at wavelength 665 nm (Rrs665) reveal the effects of physical processes governing both the spatial and temporal turbidity distribution. The results exhibit seasonal and interannual fluctuations driven by rainfall, freshwater discharges from Alcalá del Río dam, and the North Atlantic Oscillation index (NAO), with maximum turbidity levels in late autumn and winter. In addition, the temporal 1-month lag of Chl maximum and peak turbidity suggests a coupling between sediment resuspension and blooms, whereas extreme turbidity is limiting light availability for photosynthesis. Furthermore, turbidity varies on fortnightly scales, presenting lower intensity during neap tide and vice versa during spring tide. An asymmetric behavior of plume signals in connection with the semidiurnal tidal cycle is found, with maximum values during low tide. Both fortnightly and semidiurnal regimes appear to be superimposed on the large time-scale variability and occur throughout the year. Chl concentrations are dominated by the fortnightly-driven turbidity features throughout the year with minimum Chl during spring tides. This study evidences the main mechanisms influencing plume patterns and Chl, characterizing for the first time their variability in relation with tidal forcing, and therefore advancing the understanding of sediment dynamics and its relevant impact on the regulation of the pelagic ecosystem of the basin. The information obtained is critical for supporting scientists, stakeholders and ecosystem policy-makers for the challenging sustainable coastal management of the Eastern Gulf of Cádiz and its resources.

A novel approach for toluene gas treatment using a downflow hanging sponge reactor.

A novel gas-scrubbing bioreactor based on a downflow hanging sponge (DHS) reactor was developed as a new volatile organic compound (VOC) treatment system. In this study, the effects of varying the space velocity and gas/liquid ratio were investigated to assess the effectiveness of using toluene gas as a model VOC. Under optimal conditions, the toluene removal rate was greater than 80%, and the maximum elimination capacity was observed at approximately 13g-Cm-3h-1. The DHS reactor demonstrated slight pressure loss (20Pa) and a high concentration of suspended solids (up to 30,000mg/L-sponge). Cloning analysis of the 16S rRNA and functional genes of toluene degradation pathways (tmoA, todC, tbmD, xylA, and bssA) revealed that the clones belonging to the toluene-degrading bacterium Pseudomonas putida constituted the predominant species detected at the bottom of the DHS reactor. The toluene-degrading bacteria Pseudoxanthomonas spadix and Pseudomonas sp. were also detected by tmoA- and todC-targeted cloning analyses, respectively. These results demonstrate the potential for the industrial application of this novel DHS reactor for toluene gas treatment.

Comparison of filtration and treatment performance between polymeric and ceramic membranes in anaerobic membrane bioreactor treatment of domestic wastewater

Abstract The feasibility of an anaerobic ceramic membrane bioreactor (AnCMBR) was investigated by comparison with a conventional anaerobic membrane bioreactor (AnMBR). With regard to treatment performance, the AnCMBR achieved higher organic removal rates than the AnMBR because the ceramic membranes retained a high concentration of biomass in the reactor. Despite a high mixed liquor suspended solid (MLSS) concentration, the AnCMBR exhibited lower membrane fouling. To elucidate effects of sludge properties on membrane fouling in the AnCMBR and AnMBR, soluble microbial products (SMPs) and extracellular polymeric substances (EPSs) were analyzed. The SMP and EPS concentrations in the AnCMBR were higher than in the AnMBR. This may be because some suspended solids bio-degraded and likely released protein-like SMPs in the AnCMBR. Hydrophobicity and surface charges were analyzed; the sludge in the AnCMBR was found to be more hydrophobic and less negative than in the AnMBR because protein was abundant in the AnCMBR. Despite the adverse properties of the sludge in the AnCMBR, it showed more stable filtration performance than the AnMBR. This is because the alumina-based ceramic membrane had a superhydrophilic surface and could thus mitigate membrane fouling by hydrophilic-hydrophobic repulsion. The findings from this study have significant implications for extending the application of AnCMBRs to, for example, treatment of high-strength organic waste such as food waste or livestock manure.

The Source of Toxicity of Backwash Water from a Swimming Pool Filter Bed Washings

Abstract The necessity of reducing the operating costs of swimming pools leads to attempts to reuse of backwash water from washing swimming pool filter beds. Their use for watering plants, sprinkling tennis courts and play fields, draining to nearby watercourses or even returning to swimming pool installations is taken into consideration. Current researches proved the toxicity of these waste streams. The results of these studies raise doubts about the rightness of the attempts to introduce washings from pool filters directly into the environment. The aim of the presented work is to determine the source of toxicity of filter backwash water. The assessed in the work washings were characterized by high turbidity, high content of both suspended solids and organic compounds. A decrease in value of general impurity indicators after the filtration process of washings has been shown, suggesting that the main source of toxicity may be the suspension, including various anthropogenic organic micropollutants. Although this is just a research hypothesis. For this reason, comparative studies on the occurrence of toxic organic micropollutants in raw filter backwash water, supernatant water and filtrate collected after the filtration process were carried out.

Wpływ pokrycia dachu na ilość i wielkość zawiesin w spływach deszczowych

Among various drainage surfaces which allow rainwater to be utilised locally, roofs are frequently chosen solution. This is because they represent a big share of all sealed surfaces in cities and discharged liquids are considered potentially clean. Scientific reports confirm that pollutants accumulate on roofs and influence the quality of discharged water. Suspended solids are the biggest group of pollutants which occur in runoffs. The selection of rainwater pre-treatment installation and further use of the water depends on the concentration of suspended solids and their particle size. This article describes results of a research concerning suspended solids discharged from roofs made of traditional materials as well as green-roofs located in urban areas. The quantity and size of particles were assessed against rainfall characteristics: rainfall depth, length of antecedent dry weather periods and season. Results of the research show diversity of concentration levels and size of suspended solids within runoffs in reference to roofing materials, rainfall characteristics and season. The highest concentrations of suspended solids in runoff from traditional roofs were observed during rainfall depth less than 5 mm, after ancedent dry weather periods more than 50 h and in winter. These parameters did not have significantly influence on the low concentrations of suspended solids in runoff from green roofs. Suspended solids particles with the size of up to 200 μm constitute the biggest share of all roof runoffs.

Physico–chemical Characteristics and Dewatering Aptitude of sMBR Sludge

Biomass concentrations 2 to 5 times higher than in a conventional activated sludge (CAS) process can be achieved in a membrane bioreactor system (MBR). These non–conventional operating conditions, i.e. high sludge concentration, can induce different sludge characteristics and dewatering aptitude, essential parameters for the optimization of the sludge post–treatment, like mechanical dewatering. The objective of this work is to study the dewatering behavior of MBR sludge, and particularly the influence of high total suspended solids concentration, on viscosity and on the key dewaterability indicators. Operating conditions are chosen to obtain MBR sludge with constant characteristics, except TSS concentration. The results confirm that the sludge viscosity is dependent on the TSS concentration. The high viscosity obtained for high TSS concentration can be unfavorable to an efficient mixing in the MBR unit, as well as to acceptable membrane permeability. However, good settleability is obtained with high TSS concentration although the sludge presents high compressibility property and a large part of bound water. This large part of bound water seems to not disturb the sludge filterability, which stays relatively good in comparison with CAS. Consequently, high–TSS concentration in MBR system can be coherent with an efficient sludge post–treatment.

Removal of Turbidity from Travertine Processing Wastewaters by Coagulants, Flocculants and Natural Materials

The sedimentation behaviour of travertine-processing wastewater containing a high concentration of suspended solids was investigated using different coagulation and flocculation methods. In batch experiments, four types of coagulants [FeC13, Al2(SO4)3, PACl, NaAlO2], six types of flocculants (40% MMW–40% HMW cationic, 30% MMW, 40% MMW, 40% HMW anionic and nonionic) and three types of natural materials (NMs) (sepiolite, zeolite, and pumice) were used to treat wastewater with an initial turbidity of 570–880 NTU. The optimum process conditions (dosage, mixing time/speed, sedimentation time, and pH) were investigated for each. Sedimentation performance was assessed by the effluent turbidity (T eff) values of the treated water. The best performances obtained were 99.3% (T eff = 4 NTU), 99.1% (T eff = 8 NTU), and 97.8% (T eff = 18 NTU) with 40% HMW anionic-cationic flocculants, zeolite, and FeCl3, respectively. Sludge properties, including sludge settling velocity (mm/min), sludge density (g/cm3), suspended solids (SS) content (mg/L), and sludge solids (%) were determined and compared under optimized conditions. The type of additive significantly affected performance. Travertine processing wastewater flocculation with polymeric materials and NMs, especially zeolite, was more favourable than coagulants in terms of both turbidity removal and sludge quality. Since zeolite is a NM, additional studies on using and recycling of the generated sludge as an industrial feedstock would be worthwhile.

Water quality assessment in the Bétaré-Oya gold mining area (East-Cameroon): Multivariate Statistical Analysis approach

The influence of gold mining activities on the water quality in the Mari catchment in Bétaré-Oya (East Cameroon) was assessed in this study. Sampling was performed within the period of one hydrological year (2015 to 2016), with 22 sampling sites consisting of groundwater (06) and surface water (16). In addition to measuring the physicochemical parameters, such as pH, electrical conductivity, alkalinity, turbidity, suspended solids and CN−, eleven major elements (Na+, K+, Ca2+, Mg2+, NH4+, Cl−, NO3−, HCO3−, SO42−, PO43− and F−) and eight heavy metals (Pb, Zn, Cd, Fe, Cu, As, Mn and Cr) were also analyzed using conventional hydrochemical methods, Multivariate Statistical Analysis and the Heavy metal Pollution Index (HPI). The results showed that the water from Mari catchment and Lom River was acidic to basic (5.40<pH<8.84), weakly mineralized (6.3<EC<160.8μS/cm) and had a high concentration of total suspended solids (TSS) (2<TSS<8996.00mg/L). The major elements were all within the World Health Organization (WHO) guidelines for drinking water quality, except for nitrates in some wells, which was found at a concentration >50mg NO3−/L. This water was found as two main types: calcium magnesium bicarbonate (CaMg-HCO3), which was the most represented, and sodium bicarbonate potassium (NaK-HCO3). As for trace elements in surface water, the contents of Pb, Cd, Mn, Cr and Fe were higher than recommended by the WHO guidelines, and therefore, the surface water was unsuitable for human consumption. Three phenomena were responsible for controlling the quality of the water in the study area: hydrolysis of silicate minerals of plutono-metamorphic rocks, which constitute the geological basement of this area; vegetation and soil leaching; and mining activities. The high concentrations of TSS and trace elements found in this basin were mainly due to gold mining activities (exploration and exploitation) as well as digging of rivers beds, excavation and gold amalgamation.

Evaluation of the wastewater generated in the purification of biodiesel

ABSTRACTThis study quantified the pollutants in the wastewater (WW) of biodiesel. Density, number of acid, and viscosity were determined for biodiesel quality characteristics. The characterization of the effluents was performed according to the Mexican Environmental Norm. The viscosity was higher than the normalized limit (>5mm2/s). The WW had high concentrations of total suspended solids (TSS; >730 mg/l) and fat and oil (>1810 mg/l), the latter with significant differences (P > 0.05), and presented toxicity (>35000 mg/l), due to the presence of oil. Therefore these should not be discharged into the sewage networks or water bodies, considering the possible adverse effects in the environment.

Utilización de microalgas de la división Chlorophyta en el tratamiento biológico de drenajes ácidos de minas de carbón

El impacto ambiental generado por las aguas residuales de la explotación de carbón es significativo por la carga contaminante que estas por lo general poseen, representada en grandes concentraciones de sólidos suspendidos, metales (principalmente hierro) y otros elementos traza, además del bajo pH que suelen tener. El objetivo del presente trabajo fue evaluar la eficiencia de un sistema de tratamiento biológico a partir de microalgas de la división Chlorophyta para remover la carga contaminante de las aguas residuales de una mina de la empresa Coal North Energy S.A.S. Al final del tratamiento se obtuvieron porcentajes de remoción del 66,67% para hierro total, 46,67% para cloruros y 95,1% para DQO (Demanda Química de Oxígeno).

Continuous bioethanol fermentation from wheat straw hydrolysate with high suspended solid content using an immersed flat sheet membrane bioreactor

Finding a technological approach that eases the production of lignocellulosic bioethanol has long been considered as a great industrial challenge. In the current study a membrane bioreactor (MBR) set-up using integrated permeate channel (IPC) membrane panels was used to simultaneously ferment pentose and hexose sugars to ethanol in continuous fermentation of high suspended solid wheat straw hydrolysate. The MBR was optimized to flawlessly operated at high SS concentrations of up to 20% without any significant changes in the permeate flux and transmembrane pressure. By the help of the retained high cell concentration, the yeast cells were capable of tolerating and detoxifying the inhibitory medium and succeeded to co-consume all glucose and up to 83% of xylose in a continuous fermentation mode leading to up to 83% of the theoretical ethanol yield.