Intermittent Sand Filters Research Articles

Removal of emerging contaminants from wastewater through pilot plants using intermittent sand/coke filters for its subsequent reuse

Effluents from wastewater treatment plants (WWTPs) are widely recognized as the main source of emerging contaminants (stimulants and antibiotics). In this study, intermittent sand and/or coke filters were installed as a tertiary treatment at the outlet of a secondary settling tank at the WWTP in Medina Sidonia, Spain. Regular sampling followed by solid-phase extraction (SPE) and analysis by liquid chromatography-mass spectrometry (UPLC-MS) showed the complete removal of the concentrations of the emerging contaminants (caffeine, theobromine, theophylline, amoxicillin and penicillin G). Moreover, optimal filtration conditions for the reuse of treated water were presented.

English

This work aims to investigate the influence of polishing ponds (PP) depth on the post-treatment of sanitary sewers. Two treatment systems were designed and monitored. One system was an upflow anaerobic sludge blanket (UASB) rector and intermittent flow sand filter; followed by a PP of 0.20 m depth with low superficial application rate (24.9 kgBOD5.ha-1.day-1), high sunlight incidence (597 Wm-2) and enough biological carbon dioxide used to raise the average pH to 9.6, ensure an average removal of 81% orthophosphate and concentration of Escherichia coli lower than 103UFC/100 ml, which are the meeting requirements for unrestricted irrigation. The other system was a UASB followed by two PPs operated in parallel, at 0.20 and 0.60 m depths. The 0.20 m PP depth removed 80% of total Kjeldahl nitrogen, 53% of total phosphorus and 44% of orthophosphate. The 0.60 m pond depth showed low nutrient removal and a poor E. coli removal efficiency, 98.33% equivalent to 2 logs units. The ponds were fed by continuous systems. Key words: Nutrient removal, polishing ponds, disinfection, sunlight.

Reuse of sewage treated effluent in agricultural practices: An alarming presence of Giardia spp. cysts

It was evaluated the removal efficiencies of Giardia spp. cysts and helminth eggs by a simplified system of wastewater treatment. The treated effluent was checked to be reused in agricultural practices. The system was composed by anaerobic filter and intermittent sand filter. Final effluent concentration was: COD of 52±24mgL−1, TSS of 17±20mgL−1 and low turbidity values (3±4 UT). The anaerobic filter could remove 99.7±28.7% of estimated cysts concentration in the raw sewage. The sand filter removed 38.0±31.6% of Giardia spp. cysts from the anaerobic effluent, inducing the total efficiency of the system to 99.8%. The system could also remove 100% of helminth eggs. However, we also identified 93±92 cysts L−1 in the final effluent. Thus, there is a necessity to further study these decentralized systems in order to prevent the spread of infectious parasites forms in agricultural practices.

Full-scale evaluation of aerobic/extended-idle regime inducing biological phosphorus removal and its integration with intermittent sand filter to treat domestic sewage discharged from highway rest area

Biological phosphorus removal (BPR) has been demonstrated to be successfully achieved in the aerobic/extended-idle (AEI) wastewater treatment regime in previous bench-scale studies. To date, however, its feasibility has never been evaluated by any full-scale investigation. Here we report a first full-scale (180m3/day) evaluation of the AEI process and its integration with intermittent sand filter to treat highway rest area sewage that is often neglected but actually brings significant impacts on receiving water bodies in China. The results showed that 70–99% of influent phosphate was removed in the AEI zone, although the sewage contained 23–37% of carbohydrate that is usually considered to be detrimental for BPR. Batch experimental investigation revealed that the presence of glucose (model compound of carbohydrate) promoted the AEI-inducing BPR efficiency, as opposed to deteriorating the conventional anaerobic/oxic regime-inducing BPR performance. Although the performance of AEI zone was affected by seasonal variation, the efficiencies of contaminant removal were stable and excellent (total nitrogen>86%, others>92%) in the integrated system. This study offers an attractive option for BPR from carbohydrate-rich wastewaters and also provides a prototype for wastewater treatment in remote areas.

Nitrification process modeling in intermittent sand filter applied for wastewater treatment

The aim of this study was to propose a nitrification process modeling in an intermittent sand filter (ISF) using the biofilm compartment of Aquatic Systems Simulations (AQUASIM) software and the activated sludge model (ASM1) published by Henze et al. (2000). We verified that the software and the initial modeling of equations were suitable for the nitrification modeling until the hydraulic loading rate of 400Lm−2d−1, organic loading rate of 155.6gCODm−2d−1 and nitrogen loading rate of 20.4gN-NH4+-Nm−2d−1. In order to adapt the modeling for all hydraulic loading rates (HLR) studied, the set of equations was complemented with the inclusion of an F factor. This factor adapts the ASM1 model to the condition of lesser interaction between influent and the biofilm due to hydraulic loading rate increasing. Thus, the AQUASIM software along with the proposed new modeling was able to simulate the process for all HLR ranging from 100 to 800Lm−2day−1.

Chemical properties of a Haplustalf soil under irrigation with treated wastewater and nitrogen fertilization

ABSTRACT The objective of this research was to investigate the effects of irrigation with treated wastewater and nitrogen (N) fertilization on the chemical characteristics of a Haplustalf soil cultivated with cotton. An experiment was conducted in a greenhouse in a completely randomized design with four replicates, and arranged in a 5 x 4 factorial. Five doses of N fertilization (0, 45, 90, 135 and 180 kg ha-1) and four sources of irrigation water (freshwater, wastewater treated by an anaerobic reactor, wastewater treated by an anaerobic reactor and post-treated by intermittent sand filter in series, wastewater treated in a septic tank and post-treated by an intermittent sand filter) were tested. Irrigation was daily performed from July 2011 to January 2012 according to the water demand of cotton resulting in a water depth of 620 mm. It was found that, compared with the conventional management with freshwater irrigation, treated wastewater provides greater accumulation of micronutrient, potassium and sodium in the soil, increasing the risk of sodification in irrigated areas.

The impact of fractionation of hydraulic load on oxidation performances of sand filters

Infiltration–percolation is an extensive treatment technique aimed at eliminating organic matter, oxidizing nitrogen, and removing pathogens. The main purpose of this work is to evaluate the impact of fractionation of hydraulic load on oxidation performances of unsaturated sand filters. Experimental results showed that oxidation of organic matter and ammonium nitrogen has mainly occurred in the upper layers of the filter bed. They also showed that treatment efficiency increased with the increase of the thickness of the filtering mass and the fractionation of applied hydraulic load. The experiments pointed out the influence of the fractionation of daily load on oxidation capacity of the intermittent sand filter. Results showed that increasing the fractionation improves the purification capacity of the treatment process. The simulations showed that biomass growth is very sensitive to the fractionation of hydraulic load, and that the increase of the number of feeding–drainage cycles per day leads to accumulate purifying biomass in the upper layers of unsaturated filters.

Ambiance rose production and nutrient supply in soil irrigated with treated sewage

<title>ABSTRACT</title><p>Effluents from secondary sewage treatment plants may contain amount of nutrients with the potential to cause eutrophication of water bodies. One of the ways to decrease this influx of nutrients would be the agricultural reuse. Therefore, the objective of this study was to evaluate the irrigation of roses of the Ambiance variety with the effluent from an anaerobic reactor and an intermittent sand filter (nitrified effluent). The trial lasted for 152 days. The dose of nitrogen applied via effluent was 91% of the crop requirement; of phosphorus, 3.5% (very low); and of potassium, 23%. There was no difference among treatments for the evaluated variables: diameter and length of stem, diameter and length of bud, and fresh weight of flower buds. The production of floral stems was higher in treatments with effluents without conventional fertilization. It is concluded that the irrigation with a treated effluent is an alternative for the fertilization of ambiance roses.</p>

Denitrification on upflow-anaerobic filter filled with coconut shells (Cocos nucifera)

This paper studied the denitrification in an upflow-anaerobic filter filled with coconut shells (Cocos nucifera). We sought to remove nitrogen in decentralized systems, reducing the diffuse contamination of groundwater and water bodies by nitrate. The upflow-anaerobic filter was operated under hydraulic retention time (HRT) of 16h and on the bottom, there was an inflow of a combination of raw sewage and nitrified effluents from an intermittent sand filter. The research was divided into 5 stages in which there was an inflow of the following combination of raw sewage and nitrified effluent: Stage 1: 100.0%/0.0%; Stage 2: 87.5%/12.5%; Stage 3: 75.0%/25.0%; Stage 4: 62.5%/37.5%, and Stage 5: 50.0%/50.0%. The upflow-anaerobic filter promoted denitrification in all stages with a quick acclimatization of the denitrifying biomass. In the most critical situation (Stage 5), in which there was an inflow of 46.9mgL−1 of nitrate, a transformation of 98% of such compounds was found. On the effluent, the nitrate concentration obtained did not exceed 1.0mgL−1. So we found that a simple recirculation of nitrified effluent to anaerobic filters can contribute to the reduction of diffuse pollution of nitrate in remote areas of large cities or in rural areas.

Application of Reclaimed Wastewater in the Irrigation of Rosebushes

The use of reclaimed wastewater in agriculture can be a solution for regions with water shortages or low rainfall periods; besides fulfilling the crop's water needs, it would also promote the recycle of nutrients. However, care should be taken regarding soil salinization, especially in closed environments such as greenhouses for the cultivation of ornamental plants. The domestic effluents are rich in sodium which can accumulate on soil and cause soil sealing. This study evaluated the use of effluents from anaerobic filters and intermittent sand filters in the production of rosebushes (Rosa hybrida “Ambiance”). The crop yield of the rosebushes irrigated with reclaimed wastewater exceeded the one obtained with traditional cultivation, reaching a value 31.8 % higher when employing nitrified effluent originated from intermittent sand filters, with no difference in the product quality. The salinity levels are below the critical limits found in the literature; however, there was a significant increase compared to the irrigation with drinking water.

Simulation of water flow and solute transport in intermittent sand filter

Research Article| February 01 2012 Simulation of water flow and solute transport in intermittent sand filter Mahmoud Bali; Mahmoud Bali 1Department of Geology, Faculty of Sciences, Tunis, Tunisia E-mail: mahmoud.bali@yahoo.fr Search for other works by this author on: This Site PubMed Google Scholar Moncef Gueddari Moncef Gueddari 1Department of Geology, Faculty of Sciences, Tunis, Tunisia Search for other works by this author on: This Site PubMed Google Scholar Journal of Water Supply: Research and Technology-Aqua (2012) 61 (1): 50–57. https://doi.org/10.2166/aqua.2012.104 Article history Received: December 25 2010 Accepted: November 15 2011 Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Share Icon Share Facebook Twitter LinkedIn MailTo 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 Mahmoud Bali, Moncef Gueddari; Simulation of water flow and solute transport in intermittent sand filter. Journal of Water Supply: Research and Technology-Aqua 1 February 2012; 61 (1): 50–57. doi: https://doi.org/10.2166/aqua.2012.104 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex Water and solute transport in intermittent sand filtration was simulated with a modified HYDRUS 1D program. Field trials were performed through a 10 × 10 m infiltration basin located at Dissa agriculture area in the north of Gabes city (south-east Tunisia). Performance of the calibrated model has been statistically evaluated for its ability to predict water flow and solute transport. Comparisons between measured and simulated water content resulted in R2 and root mean square error (RMSE) average values of 0.88 and 0.74 cm3 cm−3 for the calibration period and of 0.86 and 0.78 cm3 cm−3 for the validation period, respectively. Predicted water quality parameters were found to be in best agreement with the measured results. On average, the model predicted COD and NH4-N concentrations well, with a RMSE of 1.06 and 1.26 mg L−1 respectively. However, it underestimated NO3-N concentration. Similar corresponding values were computed for the validation period indicating that the model is able to predict water flow and solute transport with a reasonable degree of accuracy. intermittent sand filtration, simulation, treatment, wastewater This content is only available as a PDF. © IWA Publishing 2012 You do not currently have access to this content.

Removal of contaminants and pathogens from secondary effluents using intermittent sand filters

Intermittent infiltration percolation of wastewater through unsaturated sand bed is an extensive treatment technique aimed at eliminating organic matter, oxidizing ammonium and removing pathogens. The main purpose of this study was to determine the depuration efficiencies of a sand filter to remove contaminants from secondary wastewater effluents. Elimination of pathogenic bacteria (total and faecal coliforms, streptococci) and their relationship with the filter depth were investigated. Results showed a high capacity of infiltration percolation process to treat secondary effluents. Total elimination of suspended solids was obtained. Mean removal rate of BOD(5) and COD was more than 97 and more than 81%, respectively. Other water quality parameters such as NH(4)-N, TKN and PO(4)-P showed significant reduction except NO(3)-N which increased significantly in the filtered water. Efficiency of pathogenic bacteria removal was shown to mainly depend on the filter depth. Average reductions of 2.35 log total coliforms, 2.47 log faecal coliforms and 2.11 log faecal streptococci were obtained. The experimental study has shown the influence of the temperature on the output purification of infiltration percolation process.

Bacterial, viral and turbidity removal by intermittent slow sand filtration for household use in developing countries: Experimental investigation and modeling

A two-factor three-block experimental design was developed to permit rigorous evaluation and modeling of the main effects and interactions of sand size ( d 10 of 0.17 and 0.52 mm) and hydraulic head (10, 20, and 30 cm) on removal of fecal coliform (FC) bacteria, MS2 bacteriophage virus, and turbidity, under two batch operating modes (‘long’ and ‘short’) in intermittent slow sand filters (ISSFs). Long operation involved an overnight pause time between feeding of two successive 20 L batches (16 h average batch residence time (RT)). Short operation involved no pause between two 20 L batch feeds (5 h average batch RT). Conditions tested were representative of those encountered in developing country field settings. Over a ten week period, the 18 experimental filters were fed river water augmented with wastewater (influent turbidity of 5.4–58.6 NTU) and maintained with the wet harrowing method. Linear mixed modeling allowed systematic estimates of the independent marginal effects of each independent variable on each performance outcome of interest while controlling for the effects of variations in a batch’s actual residence time, days since maintenance, and influent turbidity. This is the first study in which simultaneous measurement of bacteria, viruses and turbidity removal at the batch level over an extended duration has been undertaken with a large number of replicate units to permit rigorous modeling of ISSF performance variability within and across a range of likely filter design configurations and operating conditions. On average, the experimental filters removed 1.40 log fecal coliform CFU (SD 0.40 log, N = 249), 0.54 log MS2 PFU (SD 0.42 log, N = 245) and 89.0 percent turbidity (SD 6.9 percent, N = 263). Effluent turbidity averaged 1.24 NTU (SD 0.53 NTU, N = 263) and always remained below 3 NTU. Under the best performing design configuration and operating mode (fine sand, 10 cm head, long operation, initial HLR of 0.01–0.03 m/h), mean 1.82 log removal of bacteria (98.5%) and mean 0.94 log removal of MS2 viruses (88.5%) were achieved. Results point to new recommendations regarding filter design, manufacture, and operation for implementing ISSFs in local settings in developing countries. Sand size emerged as a critical design factor on performance. A single layer of river sand used in this investigation demonstrated removals comparable to those reported for 2 layers of crushed sand. Pause time and increased residence time each emerged as highly beneficial for improving removal performance on all four outcomes. A relatively large and significant negative effect of influent turbidity on MS2 viral removal in the ISSF was measured in parallel with a much smaller weaker positive effect of influent turbidity on FC bacterial removal. Disturbance of the schmutzdecke by wet harrowing showed no effect on virus removal and a modest reductive effect on the bacterial and turbidity removal as measured 7 days or more after the disturbance. For existing coarse sand ISSFs, this research indicates that a reduction in batch feed volume, effectively reducing the operating head and increasing the pore:batch volume ratio, could improve their removal performance by increasing batch residence time.

Simulation of oxidation processes and biomass growth in intermittent sand filter

Infiltration percolation is an extensive treatment process aimed at eliminating organic pollution, oxidizing ammonia and removing pathogens. The main purpose of this work was to improve, by means of a numerical model, the understanding of oxidation processes and biomass development in an intermittent sand filter. Hydrodynamic, dispersion and biologic parameters were calibrated and validated after data from the monitoring of an infiltration basin set in the Dissa area (south-east Tunisia). The predicted values were in good agreement with the observed data. Simulations confirm the influence of the filter depth and the fractionation of the daily hydraulic load on organic matter elimination and nitrogen oxidation. Results showed that increasing the fractionation improves the oxidation performances of the infiltration percolation process and leads to accumulated biomass in the upper layers of the sand filter. The model allowed simulation of biomass growth and its impact on the hydrodynamic characteristics of the filtering bed.

Different depth intermittent sand filters for laboratory treatment of synthetic wastewater with concentrations close to measured septic tank effluent

The objective of this study was to apply hydraulic and chemical oxygen demand (COD) loading rates at the upper limits of the design criteria for buried sand filters to test the sand filter depth design criteria. Over a 274-day study duration, synthetic effluent with a strength of domestic wastewater was intermittently dosed onto two sand filters of 0.2 m diameter, with depths of 0.3 and 0.4 m. Hydraulic and organic carbon loading rates of 105 L m−2 d−1 and 40 g COD m−2 d−1, respectively, were applied to the filters. The filters did not clog and had good effluent removal capabilities for 274 and 190 days, respectively. However, the 0.3 m-deep filter did experience a reduced performance towards the end of the study period. In the 0.3 and 0.4 m-deep filters, the effluent COD and SS concentrations were less than 86 and 31 mg L−1, respectively, and nitrification was nearly complete in both these columns. Ortho-phosphorus (PO4-P) removal in fine sand and laterite ‘upflow’ filters, receiving effluent from the 0.3 m-deep filter, was 10% and 44%, respectively

Effects of earthworms on surface clogging characteristics of intermittent sand filters

Intermittent sand filters (ISFs) are effective and economical in treating wastewater, but they are easy to clog up. To explore a feasible and simple method to alleviate clogging, two pilot-scale ISFs were constructed, one of which contained earthworms and the other did not. During the operation, the effects of earthworms on the hydraulic behaviour of ISFs were investigated. The results showed that both ISFs exhibited good performance in wastewater treatment. However, they showed different hydraulic characteristics although operated at the same organic loading rate (approximately 300 g m(-2) d(-1)). The ISF without earthworms clogged only after 53 d operation, and was partially recovered after 7 d resting, but after that, clogging occurred again, and more rapidly than the initial clogging event (40 d). However, water on the medium surface of the ISF with earthworms was not observed during the whole experiments. In addition, 11-13% of effective porosity and 0.015-0.026 cm s(-1) of infiltration rate were measured in the upper 20 cm of the ISF at the end of the experiments. The facts demonstrated that earthworms played a positive role in alleviating clogging and earthworms fed filter could alleviate surface clogging effectively.

Cold Climate Performance Analysis of On-Site Domestic Wastewater Treatment Systems

Household on-site septic systems with secondary wastewater treatment in Anchorage, Alaska, were sampled and analyzed for performance parameters during the winter to spring months. System types included intermittent dosing sand filters (ISF), three types of recirculating trickling filters (RTF), and suspended-growth aeration tanks. Total nitrogen from the trickling filter and aeration tank effluent was fairly uniform, at approximately 30 mg/L. Total suspended solids (TSS) means were mostly less than 15 mg/L. The 5-day biochemical oxygen demand (BODs) showed considerable variability, with means ranging from 9.2 mg/ L for ISFs up to 39.5 mg/L for one type of RTF, even though this type has shown excellent results in several test programs. The data suggested that effluent temperature within the sample range had almost no effect on effluent concentrations of BOD5 or TSS and only a small effect on the removal of total nitrogen. Non-climatic factors were probably of equal importance to treatment results.

Removal of bacterial and viral indicator in vertical flow constructed wetlands and intermittent sand filters

The removal of faecal coliforms (FC), Escherichia coli, somatic coliphages and F-specific bacteriophages was monitored over a period of 2 years in two vertical flow constructed wetlands (VFCWs) and four intermittent sand filters (ISFs) that treat pond effluent. Tracer tests (NaCl) were performed to estimate the hydraulic retention time (HRT) of the filters. The contribution of Phragmites australis to the removal of the faecal indicators was examined. The effect of media characteristics (depth, type of sand), hydraulic load and water application schedule on disinfection was also addressed. Planted and non-planted vertical sand filters were equally effective in removing microorganisms. The disinfection capacity was very sensitive to the depth and operation of the filters. HRT was the key parameter regarding filter disinfection capacity. Bacterial indicators were removed at a higher rate than viral ones. Somatic coliphages were removed at higher rates than F-specific bacteriophages.

Treatment of oil well “produced water” by waste stabilization ponds: Removal of heavy metals

Oil well produced water (PW) can serve as an alternative water resource for restricted halotolerant agricultural purposes if the main pollutants, hydrocarbons and heavy metals, can be removed to below the irrigation standards. In this work, the potential removal of cadmium(II), chromium(III) and nickel(II) from PW by chemical precipitation in biological treatment was evaluated. Precipitation as a sulphide salt was found to be a very effective mechanism, which together with biosorption, biological metal uptake, precipitation as hydroxides and carbonates could remove heavy metals down to below irrigation standards. The existence and capability of these various mechanisms was demonstrated in the performance of a continuous artificial pond followed by intermittent sand filter, achieving removals of around 95% for nickel(II) and even higher removal rates for cadmium(II), chromium(III) from artificial PW after the installation of an anaerobic stage. The treated effluent quality was higher than that required by current European standards.

Impact of design and operation variables on the performance of vertical-flow constructed wetlands and intermittent sand filters treating pond effluent

With the aim of improving the quality of the effluent from a waste stabilization pond (WSP) different types of vertical-flow constructed wetlands (VFCWs) and intermittent sand filters (ISFs) were tested at a pilot plant in Aurignac (France). The effectiveness of each design at upgrading the pond effluent was studied over a period of 2 years. Physicochemical parameters were monitored by taking composite samples over 24 h and grab samples every week. The hydraulic behaviour of the filters was studied using (NaCl) tracer tests and monitoring the infiltration rate. This paper describes the influence on the performance of the beds of: (a) the characteristics of the medium (type of sand, depth, and presence of Phragmites); (b) feed modes; and (c) the presence of an algae clogging layer. The study demonstrates the viability of VFCWs and ISFs as means of upgrading effluent from WSPs. For hydraulic loads (HL) of up to 80 cm/day, both technologies effectively retain algae, complete organic matter degradation, and nitrify the pond effluent. The presence of plants did not significantly affect the performance of the filters although it was important in terms of maintenance. The deeper filters presented better removals for all the parameter tested, due to higher hydraulic detention times (HDTs). The dosing regime and resting period duration all affected the hydraulic performance and purification efficiency of the filters.