Effect Of Hydraulic Loading Rate Research Articles

The Parameters Control of Recirculation Treatment for Leachate

The three parameters, hydraulic loading rate, organic loading rate and recirculation times have important influence on the efficiency of recirculation treatment, the recirculation experiment research removal of COD under different hydraulic loading rate, organic loading rate and recirculation times by the experimental devices built in landfill in a civil city. The result indicated that the hydraulic loading rate is the major influence parameter for leachate recirculation. When hydraulic loading rate was 30ml/L·d~200ml/L·d, COD removal efficiency was 70%~94%; However, organic loading rate has comparative minor influence on recirculation treatment; the apt recirculation times are 3 or 4 in a day; C/N of recirculation leachate have important influence on NH3-N removal rate, but the effect of hydraulic loading rate and recirculation times on NH3-N removal rate aren’t obvious.

Landfill Leachate Treatment Using SSF-FWS Constructed Wetland Planted with <i>Limnocharis flava</i> and <i>Eihhornia crassipes</i> under Different Hydraulic Loading Rate

A laboratory-scale study was conducted using a combination of SSF and FWS constructed wetland planted with Limnocharis flava and Eichhornia crassipes to treat landfill leachate. The effects of hydraulic loading rate (HLR) on pollutant removal in landfill leachate as well as the difference in performance between the planted and control system were investigated. The HLR in the system was varied at 0.39 m/d and 0.55 m/d. The results showed that the SSF-FWS constructed wetland was successful in reducing the pH value, TSS and turbidity. The removal efficiency of TSS and turbidity were achieved 98.32% and 97.43%, respectively at 0.39 m/d HLR. The study concluded that different HLR and the presence of wetland plants have given significant effects on the constructed wetland performance.

Effects of Hydraulic Loading Rate on Nutrient Removal in Multi-Stage Constructed Wetland

Hydraulic loading rate (HLR) is an important operational parameter for constructed wetland to purify wastewater. In this paper, it is the main objective to select the optimal parameter of HLR. During the four HLRs (i.e., 6 cm/d, 12 cm/d, 24 cm/d and 48 cm/d) operation period, six days were used as one stage. The experimental results showed that the best average removal rates of CODcr (59.7%) and NH3-N (89.4%) were at the HLR of 6 cm/d. In the meantime, the best average removal rate of total phosphorus (TP, 50.0%) was at the HLR of 24 cm/d. According to the low influent TP concentration, it is suggested that the HLR of 6 cm/d should be used in the multi-stage constructed wetland.

Effect of hydraulic loading rate on the efficiency of effluent treatment in a recirculating puffer aquaculture system coupled with constructed wetlands

Constructed wetlands (CWs) were integrated into an indoor recirculating aquaculture system of obscure puffer (Takifugu obscurus) for effluent treatment. The effect of hydraulic loading rate (HLR) on the efficiency of effluent treatment by CWs was examined for over a month. The CWs were operated under brackish conditions (salinity 7.4–7.6) at 3 different HLRs (0.762, 0.633, and 0.458 m d−1) 3 times, 10 days each. Overall, the CWs exhibited high efficiency in removal of total ammonium nitrogen (by 81.03–92.81%) and nitrite nitrogen (by 99.40%–99.68%). The efficiency of CWs in removal of total ammonium nitrogen, nitrate nitrogen, total Kjeldahl nitrogen, total phosphorous, and total suspended solids (TSS) increased with the decrease of HLR. The CWs operated at the 3 HLRs in a decreasing trend proves to be effective, providing a useful method for effluent treatment in commercial puffer aquaculture systems.

The Effect of Hydraulic Loading Rate and Influent Source on the Binding Capacity of Phosphorus Filters

Sorption by active filter media can be a convenient option for phosphorus (P) removal and recovery from wastewater for on-site treatment systems. There is a need for a robust laboratory method for the investigation of filter materials to enable a reliable estimation of their longevity. The objectives of this study were to (1) investigate and (2) quantify the effect of hydraulic loading rate and influent source (secondary wastewater and synthetic phosphate solution) on P binding capacity determined in laboratory column tests and (3) to study how much time is needed for the P to react with the filter material (reaction time). To study the effects of these factors, a 22 factorial experiment with 11 filter columns was performed. The reaction time was studied in a batch experiment. Both factors significantly (α = 0.05) affected the P binding capacity negatively, but the interaction of the two factors was not significant. Increasing the loading rate from 100 to 1200 L m−2 d−1 decreased P binding capacity from 1.152 to 0.070 g kg−1 for wastewater filters and from 1.382 to 0.300 g kg−1 for phosphate solution filters. At a loading rate of 100 L m−2 d−1, the average P binding capacity of wastewater filters was 1.152 g kg−1 as opposed to 1.382 g kg−1 for phosphate solution filters. Therefore, influent source or hydraulic loading rate should be carefully controlled in the laboratory. When phosphate solution and wastewater were used, the reaction times for the filters to remove P were determined to be 5 and 15 minutes, respectively, suggesting that a short residence time is required. However, breakthrough in this study occurred unexpectedly quickly, implying that more time is needed for the P that has reacted to be physically retained in the filter.

Impact of hydraulic loading rate and media type on removal of bulk organic matter and nitrogen from primary effluent in a laboratory-scale soil aquifer treatment system

The effect of hydraulic loading rate (HLR) and media type on the removal of bulk organic matter and nitrogen from primary effluent during soil aquifer treatment was investigated by conducting laboratory-scale soil column studies. Two soil columns packed with silica sand were operated at HLRs of 0.625 and 1.25 m/d, while a third column was packed with dune filtering material and operated at HLR of 1.25 m/d. Bulk organic matter was effectively removed by 47.5 ± 1.2% and 45.1 ± 1.2% in silica sand columns operated at 0.625 and 1.25 m/d, respectively and 57.3 ± 7.6% in dune filtering material column operated at 1.25 m/d. Ammonium-nitrogen reduction of 74.5 ± 18.0% was achieved at 0.625 m/d compared to 39.1 ± 4.3% at 1.25 m/d in silica sand columns, whereas 49.2 ± 5.2% ammonium-nitrogen reduction was attained at 1.25 m/d in the dune filtering material column. Ammonium-nitrogen reduction in the first 3 m was assumed to be dominated by nitrification process evidenced by corresponding increase in nitrate. Part of the ammonium-nitrogen was adsorbed onto the media, which was observed at higher rates between 3 and 5 m in silica sand column operated at HLR of 0.625 m/d and dune filtering material column operated at 1.25 m/d compared to 1.25 m/d silica.

Reactor performance in terms of COD and nitrogen removal and bacterial community structure of a three-stage rotating bioelectrochemical contactor

Integrating microbial fuel cell (MFC) into rotating biological contactor (RBC) creates an opportunity for enhanced removal of COD and nitrogen coupled with energy generation from wastewater. In this study, a three-stage rotating bioelectrochemical contactor (referred to as RBC–MFC unit) integrating MFC with RBC technology was constructed for simultaneous removal of carbonaceous and nitrogenous compounds and electricity generation from a synthetic medium containing acetate and ammonium. The performance of the RBC–MFC unit was compared to a control reactor (referred to as RBC unit) that was operated under the same conditions but without current generation (i.e. open-circuit mode). The effect of hydraulic loading rate (HLR) and COD/N ratio on the performance of the two units was investigated. At low (3.05 gCOD g−1N) and high COD/N ratio (6.64 gCOD g−1N), both units achieved almost similar COD and ammonia-nitrogen removal. However, the RBC–MFC unit achieved significantly higher denitrification and nitrogen removal compared to the RBC unit indicating improved denitrification at the cathode due to current flow. The average voltage under 1000 Ω external resistance ranged between 0.03 and 0.30 V and between 0.02 and 0.21 V for stages 1 and 2 of the RBC–MFC unit. Pyrosequencing analysis of bacterial 16S rRNA gene revealed high bacterial diversity at the anode and cathode of both units. Genera that play a role in nitrification (Nitrospira; Nitrosomonas), denitrification (Comamonas; Thauera) and electricity generation (Geobacter) were identified at the electrodes. Geobacter was only detected on the anode of the RBC–MFC unit. Nitrifiers and denitrifiers were more abundant in the RBC–MFC unit compared to the RBC unit and were largely present on the cathode of both units suggesting that most of the nitrogen removal occurred at the cathode.

The effect of hydraulic loading rate on treatment efficiency of a small constructed wetland

The effect of hydraulic loading rate on treatment efficiency of a small constructed wetland

Effects of Hydraulic Loading Rate and Filter Length on the Performance of Lateral Flow Sand Filters for On-Site Wastewater Treatment

On-site treatment of residential wastewater is important for rural and remote regions where centralized wastewater treatment may not be feasible. Sand filtration is a proven method for secondary treatment of septic tank effluent (STE) and can be an economical option where soil conditions do not favor the installation of a typical disposal field. This study investigates the hydraulics and treatment performance of eight lateral flow sand filters (LFSFs) receiving domestic STE at the Bio-Environmental Engineering Centre (BEEC) in Truro, Nova Scotia, Canada. The main objectives of this study were to evaluate the long-term treatment performance associated with the LFSFs and to investigate the effects of filter length and wastewater loading on performance. Previous research conducted at the BEEC indicated that current technical guidelines used in Nova Scotia for the design of LFSFs may be conservative and that the design of these systems could be optimized. The hydraulics and treatment performance associated wi...

Effects of hydraulic loading rate on pollutants removal by a deep subsurface wastewater infiltration system

The subsurface wastewater infiltration (SWI) system proved to be an effective and low-cost technique for decentralized sewage treatment in areas without adequate domestic treatment facilities. Field-scale experiments were conducted through a deep SWI system, with effective depth of 1.5 m, under hydraulic loading rates of 0.040, 0.065, 0.081 and 0.10 m 3/m 2 d. Taking the hydraulic and treatment efficiencies into consideration, the hydraulic loading rate of 0.081 m 3/m 2 d was recommended. Under this condition, NH 3–N, TN, and COD removal efficiencies were 86.2 ± 3.0, 80.7 ± 1.9 and 84.8 ± 2.1%, respectively. In the effluent, NH 3–N concentration declined to 2.3–4.4 mg/L, accounting for 63.2–65.6% of TN. NO 3–N concentration increased from 0.2 to 0.3 mg/L in the influent to 2.0–2.5 mg/L in the effluent. The nitrifying bacteria number declined with increased depth, while the amount of denitrifying bacteria increased. The analysis of results about the nitrifying and denitrifying bacteria distribution indicated that the most effective ranges for nitrification and denitrification process were 0.3–0.7 m and 0.7–1.5 m, respectively.

Influences of hydraulic loading rate on SVOC removal and microbial community structure in drinking water treatment biofilters

Six biofilters were used for advanced treatment of Yangtze River source water to investigate the effects of hydraulic loading rate (HLR) on pollutant removal and microbial community. HLR was found to exert significant influences on the removal efficiency of the conventional pollutants and 24 detectable semivolatile organic compounds (SVOCs). More than 85% of chemical oxygen demand and assimilable organic carbon was removed at the optimal HLR of 3.0 m h(-1). With the increase of HLR, SVOC removal showed a decreasing trend. Di-n-butyl phthalate and bis(2-ethylhexyl)phthalate, two main SVOCs in the source water, had the highest removals of 71.2% and 84.4%, respectively. Nearly 65% of 2,6-dinitrotoluene and 80% of isophorone were removed at the lowest HLR. Phylogenetic analysis showed that Escherichia coli, Shigella sp., E. fergusonii and Firmicutes bacteria predominated in the bioreactors. The dominance of E. coli in the low-HLR biofilters might contribute greatly to the high SVOC removal.

Kinetics of pollutant removal from domestic wastewater in a tropical horizontal subsurface flow constructed wetland system: Effects of hydraulic loading rate

The treatment capacity of constructed wetlands is expected to be high in tropical areas because of the warm temperatures and the associated higher rates of microbial activity. A pilot scale horizontal subsurface flow constructed wetland system filled with river sand and planted with Phragmites vallatoria (L.) Veldkamp was set up in the southern part of Vietnam to assess the treatment capacity and the removal rate kinetics under tropical conditions. The system received municipal wastewater at four hydraulic loading rates (HLRs) of 31, 62, 104 and 146 mm day −1. Removals of TSS, BOD 5 and COD were efficient at all HLRs with mean removal rates of 86–95%, 65–83% and 57–84%, respectively. Removals of N and P decreased with HLRs and were: NH 4-N 0–91%; TN 16–84% and TP 72–99%. First-order area-based removal rate constants ( k, m year −1) estimated from sampling along the length of the wetland from inlet to outlet at the four HLRs were in the range of 25–95 (BOD 5), 22–30 (COD), 31–115 (TSS), 5–24 (TN and TKN) and 41–84 (TP) at background concentrations ( C*) of 5, 10, 0, 1.5 and 0 mg L −1, respectively. The estimated k-values should not be used for design purposes, as site-specific differences and stochastic variability can be high. However, the study shows that domestic wastewater can be treated in horizontal subsurface flow constructed wetland systems to meet even the most stringent Vietnamese standards for discharge into surface waters.

Nitrogen removal in a combined vertical and horizontal subsurface-flow constructed wetland system

This study was conducted to (1) determine appropriate conditions for nitrogen removal by a combined constructed wetland (CW) system and (2) evaluate the effects of hydraulic loading rate (HLR), nitrogen loading rate (NLR), effluent recirculation, plant uptake, and seasonal change on the removal efficiency of nitrogen. A three-stage experimental CW system consisting of a vertical flow-gravel filtration (v-GF) bed without plants, a horizontal-subsurface flow (h-SSF) bed planted with Iris australis, and a vertical-subsurface flow (v-SSF) bed planted with Phragmites australis in series were fed with primary-treated domestic wastewaters. The beds with plants produced effluents of better quality than the v-GF bed without plants. It was observed that the average removal efficiencies increased as the HLR (from 100 to 30 L/m 2 d) decreased and the recycle ratios (to 100%) increased. The average removal efficiencies in the summer period were found higher of approximately 6% for the v-GF and h-SSF beds and 11% for v-SSF bed. Nitrogen removal by plant uptake was very low and only 3% ( Iris) to 7%( Phragmites) of the N-input compared to other mechanisms such as nitrification and denitrification. The volume-base first-order nitrification and denitrification removal constants (1/d) were 0.388 and 0.785 for the h-SSF bed, and 0.412 and 0.293 for the v-SSF bed, respectively.

Treatment of municipal sewage by Biological Aerated Filter (BAF) using burned clay pellet as media

The high-strength municipal sewage was treated by the two-stage Biological Aerated Filter (BAF) pilot system with microorganism carrier of burned clay pellet. The effects of hydraulic loading rate, aeration ratio, overloading, backwashing and the height of media on the performance of BAF were investigated. In higher hydraulic loading and lower ratio of aeration, the two-stage BAF may decrease effluent COD, NH2+-N and SS to less than 50 mg/L, 8.0 mg/L and 20 mg/L respectively. Moreover, the operation stability was not affected remarkably by the instantaneous overloading and periodical backwashing. The backwashing step by step was proposed to save energy and infrastructural investment. In addition, the dynamic expressions for the COD and NH2+-N removal were deduced respectively.

Pathogen and Indicator Organism Reduction Through Secondary Effluent Filtration: Implications for Reclaimed Water Production

The reduction of pathogens and indicator organisms through secondary effluent filtration was investigated at six full-scale treatment facilities, ranging in capacity from 0.04 to 1 m3/s (1 to 25 mgd). Grab samples were assayed for pathogens (cultivable enteric viruses, Giardia, and Cryptosporidium) and indicator organisms (coliforms, enterococci, Clostridium perfringens, and coliphages) quarterly under peak flow conditions from each facility over the course of 1 calendar year. Log10 removals resulting from filtration averaged 0.3 to 0.8 log10 for cultivable enteric viruses, 0.4 to 1.5 log10 for protozoan parasites, 0.01 to 3.7 log10 for indicator bacteria, and 0.3 to 1.1 log10 for coliphages. In addition to filter design (cloth, monomedium shallow- or deep-bed, or dual-media filters), differences in reduction of pathogens and indicators could be attributed to the combined effects of hydraulic loading rates, chemical addition practices, backwashing and postbackwashing operating strategies, and the effectiveness of upstream biological treatment and sedimentation.

Nitrate removal from groundwater using constructed wetlands under various hydraulic loading rates

This study set up two flow-through pilot-scale constructed wetlands with the same size but various flow patterns (free water surface flow (FWS) and subsurface flow (SSF)) to receive a nitrate-contaminated groundwater. The effects of hydraulic loading rate (HLR) on nitrate removal as well as the difference in performance between the various types of wetlands were investigated. Nitrate removal rates of both wetlands increased with increasing HLR until a maximum value was reached. The maximum removal rates, occurred at HLR of 0.12 and 0.07md−1, were 0.910 and 1.161gNm−2d−1 for the FWS and SSF wetland, respectively. After the maximum values were reached, further increasing HLR led to a considerable decrease in nitrate removal rate. Nitrate removal efficiencies remained high (>85%) and effluent nitrate concentrations always satisfied drinking water standard (<10mg NO3–NL−1) when HLR did not exceed 0.04md−1 for both FWS and SSF wetlands. The first-order nitrate removal rate constant tends to decrease with increasing HLRs. The FWS wetland provided significantly higher (p<0.05) organic carbon in effluent than the SSF wetland, while the SSF wetland exhibited significantly (p<0.05) lower effluent DO than the FWS wetland. However, there was no significant difference (p>0.05) in nitrate removal performance between the two types of constructed wetlands in this study except in one trial operating at HLR of 0.06–0.07md−1.

Effect of key design parameters on the efficiency of horizontal subsurface flow constructed wetlands

This study evaluates the effect of hydraulic loading rate (HLR), aspect ratio, granular medium size and water depth on the removal of selected contaminants in horizontal subsurface flow constructed wetlands (SSF) over a period of 3 years. Experiments were carried out in a pilot-scale SSF system comprising four pairs of lined beds of almost equal surface area (54–56 m 2 each), with the following aspect ratios: 1:1, 1.5:1, 2:1 and 2.5:1. The size of the granular medium of each pair varied from coarse granitic gravel ( D 60 = 10 mm, C u = 1.6) to small granitic gravel ( D 60 = 3.5 mm, C u = 1.7). The beds of the pair with longest aspect ratio were made shallower (0.27 m) than the rest (0.5 m). The system was sampled from May 2001 to December 2003. The results indicate that water depth is a determining factor in the performance of the SSF. Beds with a water depth of 0.27 m in general removed more chemical oxygen demand, biochemical oxygen demand, ammonia and dissolved reactive phosphorus (DRP). The HLR was also a very important factor in controlling the efficiency of the SSF. SSF with fine gravel produced effluents of better quality than those with coarse gravel; the differences were low in comparison to the effect of water depth and HLR. Aspect ratio is not important in comparison with the other factors. Water depth causes differences in the redox status of the SSF, which in turn influences the biochemical reactions responsible for the degradation of organic matter. Finally, the relative importance of the biochemical reactions controls the efficiency of the system.

Initial contaminant removal performance factors in horizontal flow reed beds used for treating urban wastewater

This study evaluates the effect of hydraulic loading rate (HLR), aspect ratio, granular medium size and water depth on the removal of selected contaminants during the start up of horizontal subsurface flow reed beds (HFRBs). Experiments were carried out in a pilot-scale HFRB system comprising four pairs of lined beds of almost equal surface area (54–56 m 2 each bed), with the following aspect ratios: 1:1, 1.5:1, 2:1 and 2.5:1. The size of the granular medium of each pair varied from coarse granitic gravel ( D 60=10 mm, C u=1.6) to small granitic gravel ( D 60=3.5 mm, C u=1.7). The beds of the pair with longest aspect ratio were made shallower (0.27 m) than the rest (0.5 m) The system was sampled weekly from May 2001 to January 2002. The results indicate that HLR and water depth are determining factors in the performance of the HFRBs. Beds with a water depth of 0.27 m removed more COD (70–80%), BOD 5 (70–85%), ammonia (40–50%) and dissolved reactive phosphorus (DRP) (10–22%) than beds with a depth of 0.5 m (60–65% for COD, 50–60% for BOD 5, 25–30% for ammonia, and 2–10% for DRP). The higher efficiency observed shallower beds was related to their less reducing conditions (average redox potential ( E) ranging from −351 to −338 mV) than beds with a depth of 0.5 m (−390 to −358 mV). The difference in E status between two bed types seems to lead to differences in the biochemical processes. In fact, denitrification was estimated to be a significant reaction in shallower beds.

Nitratfe removal in wetland microcosms

The effect of hydraulic loading rate (HLR; 5 to 20 cm day −1) and carbon addition (1-6 g dried plant material per week) was determined at two temperatures (28°C and 35°C) in 18 flow-through sediment-water wetland microcosms that were fed nitrate-contaminated water (30 mg N L −1). Nitrate removal efficiencies varied from 8% to >95%, decreasing with increasing HLRs and increasing with increasing carbon addition rates. The effect of HLR and carbon addition rate were integrated into the C:N ratio, which alone was highly predictive of nitrate removal efficiency. As nitrate removal efficiencies increased, dissolved organic carbon in the effluent also increased, as did chloroform formation potential. Nitrate-treatment wetlands may be a feasible method of remediating nitrate-contaminated groundwater.

Effect of pH, empty bed contact time and hydraulic loading rate on lead removal by granular activated carbon columns

Batch and column studies were performed to determine the effect of pH, empty bed contact time (EBCT), and hydraulic loading rate (HLR) on lead removal by granular activated carbon (GAC) columns. Lead removal increased with increasing pH, and for the majority of the adsorbate:adsorbent ratios investigated, was 100 % at pHs &lt; pHprec. Column pH was extremely important to lead removal in GAC columns. A simple acid‐base regeneration procedure was found to be effective in desorbing/resolubilizing the carbon‐bound lead and raising the pH for the subsequent treatment run. Regeneration efficiencies were often less than 100%, but column performance was not adversely affected. For 1 mg/L lead, the optimum EBCT was between 6 and 7 minutes, whereas for 10 mg/L lead it was less than 10 minutes. The effect of HLR (4.9 and 9.8 m/hr) on column performance was minimal for 1 mg/L lead, whereas at 10 mg/L lead column removal was slightly better at the higher HLR. Carbon usage rates were higher than those observed for wastewaters containing organic contaminants, especially at 10 mg/L lead. However, given the relatively simple regeneration scheme, the applicability of GAC columns for metal‐bearing wastewaters appears to be technically feasible.