ORP Values Research Articles

炭酸化製鋼スラグを活用した海域底質からのリンの溶出防止

The control of phosphorus release from eutropHicated coastal sediment by a carbonated steelmaking slag was examined. Batch experiments showed the following. Without slag addition, the pH, DO and ORP of seawater easily decreased with the progress of coastal sediment corruption. Moreover, phosphorus release from coastal sediment occurred rapidly. On the other hand, with steelmaking slag addition, the decreases in pH and DO were inhibited and the high ORP values of seawater were maintained. Phosphorus release from coastal sediment was clearly inhibited by slag addition. Even when the carbonated steelmaking slag was compared with sand, phosphorus release from coastal sediment was further improved. In the mechanism of phosphorus release control through steelmaking slag addition, it was considered that a carbonated steelmaking slag promotes calcium hydroxyapatite (HAP) generation induced by the high Ca2+ concentration of seawater. Furthermore, continuous experiments for more than 300 days showed that pH control and phosphorus release control from coastal sediment by carbonated steelmaking slag addition were maintained for a long term.

Enhanced cellulose-hydrogen production from corn stalk by lesser panda manure

In this study, the predominant H 2-producing bacterial strain was isolated from a bio-reactor fed with lesser panda manure, and identified as Clostridium sp. based on 16S rDNA gene analysis. The bio-pretreatment of corn stalk was found to be most effective at ambient temperature of 25 °C, microbe additive of 7.5 g/kg with saccharification period of 15 days under the anaerobic condition. The maximum H 2-production yield (176 ml H 2/g-TS) and rate (18 ml H 2/g-TS h −1) were achieved at operating pH 5.5, 36 °C and substrate concentration of 15 g/L. The H 2 content in the biogas was 44.3–57.2% (v/v) and there was no significant methane gas observed. During the optimal period of H 2 production, the ORP values stayed in the lower level ranging from −445 mV to −455 mV. The results indicated that the effluent was composed mostly of butyric acid and acetic acid, which accounted for 70–80% of total VFAs, followed by small amounts of butanol and propionate.

Sertoli cell-only pattern (SCO) does not always cause elevated FSH: impact on sperm retrieval results in non-obstructive azoospermia (NOA)

OBJECTIVE: To evaluate predictors of sperm retrieval success by microdissection TESE (mTESE) in males with NOA of SCO histology. To delineate the relationships between FSH and testicular volume in this subgroup. DESIGN: Retrospective cohort. MATERIALS AND METHODS: Serum FSH was measured in 373 males with biopsy-documented SCO who underwent mTESE for sperm retrieval by a single urologist (PNS). Azoospermia was confirmed on the day of mTESE. mTESE was performed using an operative microscope with extensive search for sperm for ICSI. Pregnancy was defined as presence of fetal heart detected on ultrasound. The primary outcome was detection of sperm with mTESE. Multivariable logistic regression assessed the association between testis volume, log-transformed FSH and mTESE success with a significant p-value<0.05. From this model, associations were estimated for specific odds ratios for easier interpretation. RESULTS: mTESE was successful in 45.3% (169/373) of patients with SCO. Surprisingly, mTESE failed in men with lower FSH (P<0.001) and larger testis volume (P=0.03). By regression to adjust for FSH, the odds of retrieval is significantly lower for men with SCO who had larger testis volume >10cc as compared to smaller <10cc (OR 0.15, 95% CI 0.03 to 0.84, P=0.03). Interestingly, the ability of FSH to predict odds of retrieval depends on testis size. For testes<10cc, FSH does not affect odds of sperm retrieval (OR 1.21, 95% CI 0.72 to 2.03, P=0.47), whereas for testes >10cc, an increase in FSH actually favors success (OR 2.57 per unit increase in logFSH, 95% CI 1.41 to 4.65, P=0.002). Table 1 outlines increasing odds of success with different FSH cutoffs in the larger testis volume group. Of those with successful sperm retrieval, fertilization failed in 6.9% while pregnancy and miscarriage rates were 51% and 7.4%. CONCLUSIONS: Men with SCO may have normal FSH, which commonly occurs in men with larger testicular volume. mTESE success is lower for men with larger testes and normal FSH. This finding suggests that despite more Leydig and Sertoli cells maintaining endocrine feedback, spermatogenesis is commonly absent for SCO males with low FSH. However, it is reassuring that if sperm are found, pregnancy rates are not affected.Table 1Odds of sperm retrieval in men with larger testis volume (>10cc) as predicted by different FSH levelsFSH (IU/mL)OR (95% CI)P-value(Reference) 7.61.0101.3 (1.1-1.5)0.002151.9 (1.3-2.8)“202.5 (1.4-4.3)“303.6 (1.6-7.9)“404.7 (1.8-12.5)“ Open table in a new tab

Effect of pH reduction and ferric ion addition on the leaching of chalcopyrite at thermophilic temperatures

Up to now various methods including bioleaching with thermophilic archea have been studied to enhance the leaching of chalcopyrite. However, the combined effect of pH and low ORP values at thermophilic temperatures (65–80 °C) has attracted little attention. Therefore, in this work, various chalcopyrites including two concentrates and two ore minerals were leached to study the combined effect of pH and ORP. It was found that a temperature of 65 °C at an initial pH of 1.0 can lead to copper extractions comparable to those obtained in bioleaching with A. brierleyi and S. metallicus. Furthermore, at an initial pH of 1.0, the addition of Fe 3+ (200 mg/L) at concentration much lower than the usually employed (e.g. 5000 mg/L), where formation of iron salt precipitates could be avoided and low ORP values (< 450 mV) could be induced, higher leaching yields than in thermophilic bioleaching were obtained. In addition to the low ORP values derived from the presence of low amounts of Fe 3+, the notable enhancement is attributed to the generation of sufficient amounts of Fe 3+ that resulted from the oxidation of Fe 2+ by oxygen at an initial pH of 1.0 and 65–80 °C without the aid of thermophiles. The oxidation of Fe 2+ by oxygen only took place under the presence of sulfides such as Cu 2S or CuS.

Effect of Cow Manure and Saw Dust as the Additive Materials for Efficient Vermistabilization

The influence of additive materials including saw dust and cow manure in the ripening of leather sludge for the efficient vermisabilization was studied. The ripening characteristics of the leather sludge, the growth of earthworms in the growth bed and the by-products like cast were observed according to the mixing ratio of additive materials. When the mixed leather sludge of which the additive materials contents were over 20% were ripened for 50 days, the values of ORP and alkalinity were changed to the favorable ranges for earthworms, the positive (+) and below 1,000 mg/l as CaCO₃, respectively. The velocity of ripening improving the characteristics of the leather sludge was faster in the sludge mixed with cow manure than saw dust. This results could also be verified from the monitoring of the states of earthworm growth using the survival rate, the increase rate of lifeweight and the hatching rate of earthworm cocoon in the their growth bed packed with the ripened sludge. The values of CEC in cast, the vermi-stabilized sludge, were increased with the mixing ratio of additive materials, but the content of heavy metals was drcreased by the dilution effect and accumulation in the earthworm body. Above results show that the leather sludge might be efficiently stabilized by earthworms through the ripening for 50 days using additive materials. Cow manure can be used as a good additive materials for leather sludge as much as saw dust, and the optimum content of additive materials in the well-ripened leather sludge was about 30%.

A Comparative Study of Five Horizontal Subsurface Flow Constructed Wetlands using Different Plant Species for Domestic Wastewater Treatment

This project studied domestic wastewater treatment by horizontal subsurface flow (HSSF) constructed wetlands (CW) and compared the effect of four different plant species on the operating conditions, dissolved oxygen (DO), and redox potential (ORP), and their efficiency on pollutants removal. Five HSSF CWs were fed for 10 months with low loaded synthetic domestic wastewater, using theoretical hydraulic residence time of 7.6 days. The plant species under study were the following: Phragmites australis (CW1), Lythrum salicaria (CW3), Cladium mariscus (CW4) and Iris pseudacorus (CW5). CW2 was not planted and this was used as control. Qualitative measurements determined a greater growth of Lythrum salicaria and Iris pseudacorus than the others. Dissolved oxygen concentrations were very low in the entire bulk liquid of all the CWs. Also ORP values were very similar in all wetlands, dealing with facultative anaerobic environments. All planted wetlands improved pollutants removal compared with the unplanted control wetland. The performances in terms of COD, TN, TP and SO4 2− removal obtained by the different CWs were in the ranges 80-90%, 35-55%, 15-40% and 45-60% respectively. Lythrum salicaria and Iris pseudacorus, which exhibited greater growth, were always the most efficient species that improved not only nutrients plant uptake but also other microbial removal processes probably due to a higher aeration potential, such as nitrification or aerobic respiration. Sulphate reduction was the most important mechanism for COD removal. Cladium mariscus, an autochthonous plant that grows in the south-central Iberian Peninsula, was less efficient than Lythrum salicaria and Iris pseudacorus, but improved the unplanted wetland wastewater efficiency.

Effects of Operational Variables on Nitrogen Removal Performances and Its Control in a Pre‐Denitrification Plant

AbstractThe aim of this work is to study the effects of six operational variables, i.e., dissolved oxygen (DO), nitrate recirculation flow, sludge recycle flow, sludge wastage flow, external carbon dosage, and anoxic volume fraction, on the performance of nitrogen removal and its control in a pre‐denitrification plant. The results obtained show that the six operational variables have a significant influence on nitrogen removal in such a system, while the utilization of the control strategies can improve the situation to a significant extent. The control of DO concentration should be correlated with the influent ammonia load, the effluent requirement and nitrification type. The anoxic effluent nitrate concentration should be controlled at ca. 2 mg/L or the ORP value at the end of the anoxic zone should be controlled at ca. –90 mV. The control of the sludge recycling flow by online monitoring of the sludge blanket height (SBH), is an alternative to the conventional control of the constant sludge recycle flow. It may be possible to achieve the automatic control of sludge wastage flow by online measuring of the ammonia concentration and the nitrification capacity of the sludge. The recirculation of nitrate and external carbon dosage should be simultaneously controlled to optimize nitrogen removal. The anoxic volume fraction should also be optimized, to ensure a good balance between nitrification and denitrification.

Improving nitrogen removal using on-line sensors in the A/O process

A bench-scale anoxic–oxic (A/O) system was used to treat a synthetic starch wastewater for 1 year. The objectives were to improve nitrogen removal and reduce operating costs by using on-line sensors DO, pH and ORP. It is found that the DO in the first aerobic zone could be used to estimate influent ammonia load under constant aeration. The pH profiles and DO profiles along the length of aerobic zones give good indication of the nitrification, and the pH profiles in the aerobic zones and anoxic zones could be classified into two types: descending and rising type. Further, ORP value at the end of aerobic zone showed a good correlation with the effluent ammonia and nitrate nitrogen concentration, good effluent quality corresponded with the range of 40–60 mV of ORP in this study. ORP was also correlated well with nitrate concentration at the end of anoxic zone, and the maximum denitrification capacity could be achieved when ORP was maintained at about −90 mV. A fuzzy inference system for on-line aeration, nitrate recirculation flow and external carbon dosage control is developed on the basis of these observations and is implemented on the bench-scale system. Promising control performance is achieved.

Attenuation of landfill leachate at two uncontrolled landfills

Attenuation characteristics of landfill leachate were examined for two uncontrolled landfills in Korea. The two landfills containing municipal wastes without appropriate bottom liner and leachate treatment system have different landfill age, waste volume, and most importantly different hydrogeologic settings. One landfill (Cheonan landfill) is situated in an open flat area while the other (Wonju landfill) is located in a valley. Variations of various parameters including dissolved organic carbon (DOC), dissolved oxygen (DO), alkalinity, pH, electrical conductivity (EC), redox potential (ORP), ammonia (NH3), nitrate (NO3−), sulfate (SO42−), and chloride (Cl−) were examined along groundwater flow path. All these parameters were analyzed every month for a year. In the interior of the landfills, typical anaerobic conditions revealed by low DO and NO3 concentrations, negative ORP values, high NH3, alkalinity, and Cl− concentrations were observed. Generally, higher levels of contaminants (DOC, NH3, and Cl−) were detected in the dry season while they were greatly lowered in the wet season. Significantly, large decrease of Cl- concentration in the wet season indicates that the dilution or mixing is one of dominant attenuation mechanisms of leachate. But detailed variation behaviors in the two landfills are different and they were largely dependent on permeability of surface and subsurface layers. The intermediately permeable surface of the landfills receives part of direct rainfall infiltration but most rainwater is lost to fast runoff. The practically impermeable surface of clayey silt (paddy field) at immediately adjacent to the Cheonan landfill boundary prevented direct rainwater infiltration and hence redox condition of the ground waters were largely affected by that of the upper landfill and the less permeable materials beneath the paddy fields prohibited dispersion of the landfill leachate into down gradient area. In the Wonju landfill, there are three different permeability divisions, the landfill region, the sandy open field and the paddy field. Roles of the landfill and paddy regions are very similar to those at the Cheonan. The very permeable sandy field receiving a large amount of rainwater infiltration plays a key role in controlling redox condition of the down gradient area and contaminant migration. This paper reports details of the attenuation and redox conditions of the landfill leachates at the two uncontrolled landfills.

Comprehensive Analysis of the Factors for Propionic Acid Accumulation in Acidogenic Phase of Anaerobic Process

The accumulation of propionic acid in the anaerobic process often leads to a low efficiency of the methanogenic phase due to the low acetogenic rate of propionic acid, and hence the low wastewater treatment efficiency. Three acidogenic reactors were used to study the reasons for propionic acid accumulation in the acidogenic phase and its control strategy. The experimental results indicated that in the micro-aerobic circumstance (ORP>−100 mV) the accumulation of propionic acid in the acidogenic reactor always occurred at any pH value. Under strict anaerobic circumstances (ORP < −150 mV), typical propionic acid-type fermentation commonly occurred at pH about 5.5 regardless of ORP value. However, at pH about 5.0, either propionic acid-type or butyric acid-type fermentation might occur depending on whether ORP was high or low. Higher hydrogen production rate was found to have no direct relationship to the accumulation of propionic acid in the acidogenic reactors. In fact, great yield of NADH maybe the major reason for simultaneous accumulation of propionic acid and higher biohydrogen generation rate in the traditional anaerobic process. The highest biohydrogen generation rate occurred during the ethanol-type fermentation without the accumulation of propionic acid. Ethanol-type fermentation is a better choice when using an anaerobic acidogenic reactor of a two-phase separated anaerobic process to efficiently produce biohydrogen simultaneously with organic wastewater pre-treatment.

Feasibility of controlling nitrification in predenitrification plants using DO, pH and ORP sensors

Experimental studies were carried out on a bench-scale nitrogen removal system with a predenitrification configuration to gain insights into the spatial and temporal variations of DO, pH and ORP in such systems. It is demonstrated that these signals correlate strongly with the operational states of the system, and could therefore be used as system performance indicators. The DO concentration in the first aerobic zone, when receiving constant aeration, and the net pH change between the last and first aerobic zones display strong correlations with the influent ammonia concentration for the domestic wastewater used in this study. The pH profile along the aerobic zones gives good indication on the extent of nitrification. The experimental results also showed a good correlation between ORP values in the last aerobic zone and effluent ammonia and nitrate concentrations, provided that DO in this zone is controlled at a constant level. These results suggest that the DO, pH and ORP sensors could potentially be used as alternatives to the on-line nutrient sensors for the control of continuous systems. An idea of using a fuzzy inference system to make an integrated use of these signals for on-line aeration control is presented and demonstrated on the bench-scale system with promising results. The use of these sensors has to date only been demonstrated in intermittent systems, such as sequencing batch reactor systems.

Fuzzy control of nitrogen removal in predenitrification process using ORP

In order to meet increasingly stringent discharge standards, new applications and control strategies for the sustainable removal of nitrogen from wastewater have to be implemented. In the past years, numerous studies have been carried out dealing with the application of fuzzy logic to improve the control of the activated sludge process. In this paper, fuzzy control strategies of predenitrification systems are presented that could lead to better effluent quality and, in parallel, to a reduction of chemicals consumption. Extensive experimental investigations on lab scale plant studies have shown that there was excellent correlation between nitrate concentration and ORP value at the end of the anoxic zone. Results indicated that ORP could be used as an on-line fuzzy control parameter of nitrate recirculation and external carbon addition. The optimal value of ORP to control nitrate recirculation and external carbon addition was - 86 +/- 2 mV and - 90 +/- 2 mV, respectively. The results obtained with real wastewater also showed the good performance and stability of the fuzzy controllers independently from external disturbances. The integrated control structure of nitrate recirculation and external carbon addition in the predenitrification system is also presented.

Application of remote monitoring and automatic control system using neural network for small wastewater treatment plants in Korea

For this study, an automatic control system has been developed by using a neural network and internet-based remote monitoring system for efficient operation of plants that have a serious variance of influent loading and have difficulties in appropriate maintenance, just like small wastewater treatment plants in Korea. In the control algorithm, ORP was used as the main sensor for control. At the point where the ORP value was judged to reach the "nitrate knee" of denitrification and phosphorus release, ORP indicated the state of lower saturation read by the neural network and then changed the operating condition from the reduction state to the oxidation state. For example, if ORP indicates the state of higher saturation at the point of "nitrogen breakpoint" or "ammonia valley" of nitrification, the neural network reads it and cuts off the oxygen supply and mixing. The dORP data have been used as one of the main input for the neural network. After the operation of lab-scale cyclic aeration process using an automatic control system, it has been found that regardless of loading variance, more than 95% of organic matters and more than 60% of nitrogen and phosphorus have been removed. Assuming that an internet-connected computer and a basic web browser are available, this study has developed a remote monitoring system that can monitor the operating status of small plants or any troubles with them.

Evaluation of an integrated anaerobic/aerobic SBR system for the treatment of wool dyeing effluents

This work examined the performance of a sequencing batch reactor treating dyeing effluents from a factory that processes mainly wool and wool/polyester blends. Different operational conditions were evaluated, namely the influence of the anaerobic and the subsequent aerobic phase on the organic load removal, as well as the effect of the length of the aeration period (from 8 to 12 h) on process efficiency. A comparison between a fill stage in fast and slow modes was carried out. Results indicate that the cycle 2 conditions (fast fill and 12 h aeration time) improved the overall efficiency (85+/-6% soluble COD and 95+/-4% BOD5 removal yields) with a predominant COD uptake occurring in the aerobic stage. Slow, linear COD removal was observed in the anaerobic phase, in contrast with an exponential COD decrease in the oxic phase. For SS a level under 100 mg/l was general achieved in the exit of the reactor. With respect to dye degradation, a noticeable decrease of the absorbance measured in the UV-visible range was observed. This could be explained by the reduction of the azo bonds of some of the present dyes in the anaerobic step, in which ORP values lower than -400 mV were attained. Some oxidation of anthraquinone sulphonate dyes and of the aromatic amines resulting from azo bond cleavage could also have been taken place, as well as bioelimination mechanisms such as dye sorption.

Oxidation–Reduction Potential Changes in Aeration Tanks and Microprofiles of Activated Sludge Floc in Medium‐ and Low‐Strength Wastewaters

Real-time control of aeration tank operation is key to high-efficiency pollutant removal and energy savings. One of the aims of this study was to examine the potential for using redox potential (oxidation-reduction potential [ORP]) to indicate wastewater quality online in aeration tanks treating medium (chemical oxygen demand [COD] of 70 to 150 mg/L) and low (COD of 15 to 30 mg/L) pollutant-concentration wastewaters. The field-scale data provide a good relationship between ORP values and nutrient removal along the length of the aeration tanks. The ORP values increased dramatically as organic matter was removed along the aeration tanks, indicating the improvement of the bulk liquor redox status. Dissolved oxygen higher than 1.0 mg/L was necessary for good biodegradation and improvement of the liquid redox status. Nitrification occurred at higher ORP values (380 to 420 mV) than was the case for organic substrate oxidation (250 to 300 mV). The microprofiles obtained from microelectrode measurements substantiate the heterogeneity of the microbial processes inside activated sludge flocs. Because of microbial oxygen utilization, the aerobic region in the activated sludge floc was limited to the top layer (0.1 to 0.2 mm) of the activated sludge aggregate present in medium-strength wastewater, with an anoxic zone dominating inside the flocs. When dissolved oxygen in the bulk water was higher than 4.0 mg/L, the anoxic zone inside the floc disappeared. At low wastewater pollutant concentrations, the ORP and dissolved oxygen inside the activated sludge aggregates were higher than those from medium-strength wastewater. The prospect of using ORP as an online control approach for aeration tank operation and the potential reasons for activated sludge floc size varying with pollutant strengths are also discussed.

Feed-forward dose control of wastewater chlorination using on-line pH and ORP titration

In this study, a simple automatic pH–ORP titration device was developed for identifying the various ammonia concentrations and chlorine dose requirements for wastewater chlorination by identifying the peaks in the ORP-slope profiles and knees/valleys in the pH profiles. In addition, breakpoint chlorination experiments have shown that the ORP values at the monochloramine humps and breakpoints are linearly correlated with the ammonia concentrations. Therefore, a feed-forward control strategy, based on the chlorine/ammonia weight ratio (Cl/N), is proposed in this paper, to control the chlorine doses for a continuous wastewater chlorination experiment in a laboratory-scale reactor. The result of this continuous wastewater chlorination experiment has shown that the pH–ORP titration was able to precisely determine the variations of ammonia concentrations in the chlorination influent. Under this control strategy, effective and stable disinfection efficiencies in terms of total coliform count were obtained.

Applying the Nernst equation to simulate redox potential variations for biological nitrification and denitrification processes.

In this paper, various forms of Nernst equations have been developed based on the real stoichiometric relationship of biological nitrification and denitrification reactions. Instead of using the Nernst equation based on a one-to-one stoichiometric relation for the oxidizing and the reducing species, the basic Nernst equation is modified into slightly different forms. Each is suitable for simulating the redox potential (ORP) variation of a specific biological nitrification or denitrification process. Using the data published in the literature, the validity of these developed Nernst equations has been verified by close fits of the measured ORP data with the calculated ORP curve. The simulation results also indicate that if the biological process is simulated using an incorrect form of Nernst equation, the calculated ORP curve will not fit the measured data. Using these Nernst equations, the ORP value that corresponds to a predetermined degree of completion for the biochemical reaction can be calculated. Thus, these Nernst equations will enable a more efficient on-line control of the biological process.

CHARACTERIZATION OF OXIDATION-REDUCTION PROCESSES IN CONSTRUCTED WETLANDS FOR SWINE WASTEWATER TREATMENT

Constructed wetlands designed and properly operated for treatment of swine wastewater may enhanceoxidation -reduction processes and nutrient treatment performance. The objective of this investigation was to characterizesoil wetland processes related to nitrogen (N) treatment (nitrification-denitrification) and phosphorus (P) removal using soiloxidation -reduction potential (ORP) data. We evaluated three surface-flow wetland systems constructed for treatment ofswine wastewater in Duplin Co., North Carolina, in 1992. Each system consisted of two 3.6- 33.5-m cells connected inseries. The three systems were planted to bulrushes, cattails, and agronomic crops (soybean in saturated soil culture andflooded rice), respectively. Soil aerobic/anaerobic conditions were determined by monitoring soil ORP at 18 sites usingplatinum (Pt) electrodes. Three monitoring sites were established in each wetland cell. Each site consisted of five Pt electrodesat three soil depths (0.02, 0.05, and 0.10 m) and a reference electrode. A data logger was used for hourly acquisition of soilORP and temperature records. Hourly ORP data were averaged on a 24-h basis and corrected to standard hydrogen electrodereadings (Eh). Frequency analysis of daily soil Eh showed that bulrush and soybean cells were moderately reduced (+100< Eh < +300 mV) and anaerobic (Eh < +300 mV) about 70% of the time. However, cattail and rice cells were anaerobic 100%of the time and had reduced (-100 < Eh < +100 mV) to highly reduced (Eh <-100 mV) soil conditions. These results indicatethat different wetland plant species promote distinct anaerobic and reducing soil conditions. Outflow concentration ofammonia-N (NH3 -N) and soluble P increased with increasing ORP values for bulrush and soybean-rice wetland cells dueto lower temperatures during fall and winter, but not for cattails. Denitrification enzyme activities and ORP indicated thatsoils in bulrush wetlands promoted better conditions for nitrification-denitrification than cattails or rice soils. However,equivalent NH3 -N removal rates (4.8-5.6 kg ha-1 d-1) for cattails and bulrush suggested that treatment occurred mostly inthe water column for cattails rather than the wetland soil. Prevalent anaerobic soil conditions and soluble P outflowconcentrations determined rather poor P retention capacity for all three wetlands.

Microwave-Assisted Preparation of Polyferric Sulfate Coagulant

This study prepared polyferric sulfate (PFS) coagulants using a closed microwave method. In addition to reducing the requirement of adding oxidant and catalyst by applying the high pressure and high temperatures characteristic of microwave radiation, this work also adopts a newly developed continuous-flow process instead of the conventional batch production method to reduce the reaction time and prevent the energy waste. Water treatment plants can produce coagulants by themselves to meet their requirements since polyferric sulfate is easily created using this microwave method. The transport and storage expenses associated with providing reliable and fresh coagulants for water treatment can thus be reduced or eliminated. The approach specified herein has already been successfully applied to synthesize PFS products and evaluate products' physical and chemical properties, including ORP values, viscosity, salicylic acid reaction ability, and hydrolysis parameter B*. The results reveal that PFS made using the microwave method has properties similar to those of PFS made by the conventional method. Importantly, the microwave method reduces the reaction time from the 500 min of the conventional method to less than 20 min, significantly reducing the amount of energy consumed and the expense of production.

ENHANCED PHOSPHORUS REMOVAL FROM SWINE–NURSERY MANURE IN AERATED BATCH REACTORS

Phosphorusbased land application of swine manure slurry results in underapplication of nitrogen (N), whilenitrogenbased application leads to overapplication of phosphorus (P). Significant amounts of P must be removed fromswine manure to reduce P overapplication, and at the same time, safely apply targeted amounts of N. This study comparedthree schemes of soluble orthophosphate (orthoP) reduction from liquid swine nursery manure during batch aeration:(1) solidsliquid separation before aeration (preaeration solidsliquid, or PASL, separation), (2) solidsliquid separationin the middle of aeration (midaeration solidsliquid, or MASL, separation) and (3) no solidsliquid separation (control).Significantly more orthoP was converted to nonsoluble species with MASL separation (92%) than with either PASLseparation (87%) or the control (84%). MASL separation also significantly improved the removal of total phosphorus (TP)in the sludge from the liquid after an overnight sedimentation process: 80%, 70%, and 66% for MASL separation, PASLseparation, and control, respectively. Solidsliquid separation enhanced the maintenance of higher oxidation potentials(depicted by higher values of ORP in the separated manures than in the control) in the manure during the latter days ofaeration, implying that substantial energy saving is possible for prolonged aeration of separated liquid manure. This is animportant element in the postaeration treatment for ensuring that P removed from the solution stays in the sludge and is notreleased back into solution, if removal of the sludge does not immediately follow scheduled aeration treatment.