Alum Dose Research Articles

The role of aluminum in slow sand filtration

Engineering enhancement of slow sand filtration has been an enigma in large part because the mechanisms responsible for particle removal have not been well characterized. The presumed role of biological processes in the filter ripening process nearly precluded the possibility of enhancing filter performance since interventions to enhance biological activity would have required decreasing the quality of the influent water. In previous work, we documented that an acid soluble polymer controls filter performance. The new understanding that particle removal is controlled in large part by physical chemical mechanisms has expanded the possibilities of engineering slow sand filter performance. Herein, we explore the role of naturally occurring aluminum as a ripening agent for slow sand filters and the possibility of using a low dose of alum to improve filter performance or to ripen slow sand filters.

Treatment of Liming Effluent from Tannery using Membrane Separation Processes

A treatment method of liming effluent of a tannery is tested using hybrid membrane separation processes. The effluent after gravity settling and alum coagulation is subjected to ultrafiltration followed by nanofiltration. The optimum alum dose is obtained by analyzing the effluent using various concentrations of alum. The membrane separation processes are conducted in a continuous cross flow mode. The effects of operating conditions e.g., transmembrane pressure difference, and cross flow velocity (Reynolds number) on the permeate flux are analyzed. Effects of change in hydrodynamic conditions in various flow regimes, e.g., laminar, laminar with turbulent promoter, and turbulent flow on flux improvement have been studied. A resistance‐in‐series model for flux decline during the filtration process is proposed. COD, BOD, TDS, TS, pH, Ca2+ concentration, Cl− concentration and conductivity are measured before and after each operation. The potential of the dried sludge as organic fertilizer is also explored.

An investigation of the pressure applied to the face by different styles of elastic face masks

Biodiesel wastewater is known as one of the most highly polluted wastewaters with high organic load, high amount of oils and fat contents and other compound such as chloride. The aim of this study is to optimize the coagulation–flocculation process prior to pre-treat biodiesel wastewater. This paper reports the optimal process conditions which were obtained using the Response Surface Methodology (RSM) analysis. This study was done using jar test apparatus. The Box–Behnken design was demonstrated beforehand to optimize this process. The investigated operating variables were coagulant dosage, initial pH, rapid mixing rate and contact time. The optimal process conditions obtained were alum dosage of 2 g/L, initial pH of 7.13, rapid mixing rate of 200 rpm and settling time of 65 min. From the validation test conducted, the results were in reasonable agreement with the modeled values. The coagulant used in this study managed to reduce the COD, SS and turbidity contents by 34.5, 39.0 and 32.0%. respectively. Optimization of coagulation–flocculation can be done using the Response Surface Methodology (RSM) analysis and this proving that coagulation is capable of pre-treating biodiesel wastewater.

Effects of filtration temperature, humic acid level and alum dose on cryptosporidium sized particle breakthrough

Recent Cryptosporidium outbreaks have highlighted concerns about filter efficiency and especially particle breakthrough. Understanding the causes of breakthrough is essential, as the parasite cannot be destroyed by conventional disinfection with chlorine. Particle breakthrough depends on many factors. This research aims to investigate the influence of temperature, humic acid (HA) level and chemical dosing on particle breakthrough in filtration. A series of temperatures were set at 5 degrees C, 15 degrees C and 25 degrees C; humic acid level was 5 mg L(-1). Each was combined with a series of Al doses. A laser particle counter was used to assess the particle breakthrough online. Turbidity, zeta potential, and UV254 absorption were measured before and after filtration. The results showed that particle breakthrough was influenced significantly by temperature, humic acid and dosing. Particle breakthrough occurred earlier at lower temperature, while at higher temperature it was reduced at the same coagulant dose. With coagulants, even at low dose, particle breakthrough was significantly reduced. With HA 5 mg L(-1), particle breakthrough was earlier and the amount was much larger than without HA even at high temperature. There was an optimal dose in filtration and it was well correlated with zeta potential.

Application of ultrafiltration hybrid membrane processes for reuse of secondary effluent

This study evaluates the factors affecting pretreatment conditions for hybrid UF membrane processes for reuse of secondary effluent from the sewage treatment plant. The experimental results obtained from the ultrafiltration (UF) membrane process showed that the particles of the size range between 0.2 and 1.2 μm caused a significant impact on membrane fouling in all cases even with or without the coagulation process. As pretreatment of UF membrane process, the coagulation significantly improved the permeate flux. Optimal flux improvement was seen at an alum dose of 50 mg/L. In addition, it was found that the permeate flux was least declined under the coagulation condition of charge neutralization (pH 5.0). Also, the powdered activated carbon (PAC) adsorption enhanced the permeate flux. Application of the direct filtration as a pretreatment of UF membrane process was also very effective in reducing the UF membrane fouling.

Electroosmotic flow through particle beds packed with conditioned sludges

Electroosmotic flow through packed beds filled with kaolin slurries conditioned with various chemicals (KCl, alum and polymeric flocculant etc.) was experimentally studied. A theoretical expression relating electroosmotic flux to physicochemical properties of the bed was derived and agreed with experimental data at low KCl concentration. When slurries were coagulated with high alum dosages without pH adjustment, a threshold electric field strength commenced electroosmosis flow, and a hysteresis phenomenon in the electric field strength dependent on electroosmotic flow were observed. However, when slurries were conditioned by adding polymeric flocculant, both the electroosmotic flux and its flow direction were qualitatively consistent with the prediction based on the measured values of zeta potential of particles.

Coagulation/flocculation process in the treatment of abattoir wastewater

The coagulation/flocculation process was used at laboratory bench scale for the removal of chemical oxygen demand (COD), total suspended solids (TSS) and total phosphorus (TP) in abattoir wastewater. The wastewater was allowed to settle for 24 h and TSS and TP removal efficiencies of 65% and 32% were achieved, respectively. Alum, ferric chloride and ferric sulfate were employed during the coagulation/flocculation process. Alum proved more effective in the reduction of TSS and TP present in the wastewater, whereas ferric sulfate was more effective in the reduction of COD. Increasing the dose of alum to 750 mg/l caused the removal efficiency of TP to reach 45%. The rate of removal of TP linearly increased with increasing doses of alum, resulting in a 98% removal efficiency of TP at 1000 mg/l dose of alum. At a 95% confidence interval, alum dose, coagulation velocity gradient/rapid mixing time (coagulation Gt) and flocculation velocity gradient/slow mixing time (flocculation Gt) were not significant for TSS removal efficiency, but alum dose was significant for TP removal. The addition of a polyelectrolyte to an inorganic coagulant proved effective in the reduction of COD, TSS and TP, cut the amount of coagulant used and reduced the cost of the coagulation/flocculation process. A significant degree of particle elimination by size was produced by using alum; this improved further with the addition the polyelectrolyte.

Effect of SUVA and enhanced coagulation on removal of TOX precursors

This work examined the effect of raw water total organic carbon (TOC) concentration and alkalinity on the reduction of organic halide formation potential by enhanced coagulation. Enhanced coagulation is considered the best available technology for removal of disinfection by‐product (DBP) precursors. Enhanced coagulation is also mandated by the Stage 1 Disinfectants/Disinfection Byproducts Rule, which prescribes specific TOC removal requirements for the control of unidentified halogenated DBPs of potential public health concern. In this research, 27 waters were obtained from different utilities across the United States; 3 waters were obtained for each element of the 3 × 3 enhanced coagulation matrix. Jar tests were performed on each water to determine the requisite alum dose for TOC removal in accordance with the enhanced coagulation guidance manual. Each water was then treated with the requisite alum dose for enhanced coagulation, and the resulting settled waters, along with each of the raw waters, were chlorinated under uniform formation conditions. The chlorinated waters were analyzed for total organic halides (TOX). The formation of TOX in the raw waters and the effectiveness of coagulation for the reduction of TOX formation potential were compared for each of the elements in the 3 × 3 enhanced coagulation matrix. Results demonstrated the ability of specific ultraviolet absorbance to reflect the reactivity of organics in water toward removal by coagulation and toward organic halide formation potential.

Effect of coagulation on palm oil mill effluent and subsequent treatment of coagulated sludge by anaerobic digestion

AbstractA new effluent treatment scheme is proposed for treating palm oil mill effluent based on coagulation and anaerobic digestion of coagulated sludge. The effectiveness of anionic (N9901) and cationic (N9907) polyelectrolytes manufactured by NALCO (Malaysia) was evaluated both as coagulant and coagulant aid. The results showed that the anionic and cationic polyelectrolytes were best suited as a coagulant aid, and the cationic polyelectrolyte showed better performance than the anionic polyelectrolyte. For an influent chemical oxygen demand (COD) concentration of 59 700 mg L−1 at an alum dosage of 1700 mg L−1, the residual COD, suspended solid removal, sludge volume and pH were found to be 39 665 mg L−1, 87%, 260 mL L−1 and 6.3, respectively. For the above influent COD and alum dosage with the addition of 2 mg L−1 of cationic polyelectrolyte as coagulant aid, the results were 30 870 mg L−1, 90%, 240 mL L−1 and 6.2, respectively. The sludge resulting from the coagulation process using alum as coagulant and cationic polyelectrolyte as coagulant aid was tested for its digestibility in an anaerobic digester. The quantity of biogas generated per gram of volatile solids (VS) destroyed at a loading rate of 26.7 ± 0.5 and 35.2 ± 0.4 g VS L−1 d−1 was found to be 0.68 and 0.72 L g−1 VS destroyed. The anaerobic biomass when subjected to varying alum dosage in the coagulated palm oil sludge did not exhibit inhibition as the digester performance was in conformity with the regular treatment process Copyright © 2006 Society of Chemical Industry

The Use of Bentonite clay as a Coagulant or a Coagulant Aid With Alum in Turbidity Removal

The main goal of this study is to use bentonite clay as a coagulant and coagulant aid in removing different water turbidities levels in order to improve drinking water quality at economical costs. The study showed that this material as coagulant has been proven to be efficient especially at low turbidity levels (i.e. not more than 25 ntu) with a dose of not more than 25 mg/l. As a coagulant aid with alum bentonite has shown to very effective with dose as much as 15 mg/l for low and intermediate initial turbidity level (not more than 100 ntu) and with a dose not more than 30 mg/l for high initial turbidity level 500 ntu, this efficiency is be better for low initial turbidity level and with low alum dose.

Reservoir water treatment using hybrid coagulation–ultrafiltration

A new hybrid coagulation–ultrafiltration process was used to treat reservoir water for drinking purposes. Raw water collected at a local waterworks in Singapore was pretreated under optimized conditions of coagulation pH 5.2 and alum dosing concentration of 5 mg (Al)/L. A hollow-fiber UF membrane module (0.07 m 2) was used to filter the supernatant after pH correction to 7.2. The laboratory-scale UF unit with an automatic control system was used. Different feed flow rates (or membrane fluxes), backwash intervals and water recoveries were studied in the UF operation. The experimental results show that the hybrid coagulation–UF process used could remove turbidity (>99%), NOM in terms of DOC (up to 59.5%) and bacteria (>3 LRV). Turbidity and DOC of the UF permeates were 0.10 NTU max and 2.26 mg/L on average, respectively. Total coliform and total THM were not detectable. The UF membrane used had a high normalized flux of 600–700×10 −5 L m −2 h −1 Pa −1 at 25°C under the conditions of low TMP of 0.013–0.017 MPa and a high water recovery of 99%, and potentially showed low energy consumption for treating the reservoir water. It is concluded that the hybrid coagulation–UF process could be incorporated into existing conventional processes with replacement of dual-media filtration for producing an improved quality of drinking water from reservoir water.

Pretreatment chemistry for dual media filtration: model simulations and experimental studies

Laboratory dual media filtration experiments were conducted (a) in direct filtration mode using model raw water moderate in turbidity and low in DOC, and (b) in conventional filtration mode treating water moderate in turbidity and high in DOC. Model simulations of filter performance for the removal of particles provided hypotheses for the experimental studies of dual media filtration. An increase in alum dose in direct filtration mode, while improving filter performance, also showed some disadvantages, including rapid development of head loss. Suboptimal dose in direct filtration significantly impaired the filter performance. In conventional mode, the effect of alum dose on the filter performance, while obvious, was not as dramatic as in direct filtration. Ripening indicated by particle counts occurred earlier than by turbidity and breakthrough of particle counts started earlier than breakthrough of turbidity, suggesting that turbidity can be used as a more conservative monitor of filter performance during the ripening period to minimise the risk of passage of small particles, while particle counts can be considered a more sensitive indicator of deteriorating filter performance during the breakthrough period. The lower sand layer served as a multiple barrier for particle when the performance of the anthracite layer was not effective.

Effects of velocity gradient and mixing time on particle growth in a rapid mixing tank

Effects of velocity gradient (G value) and mixing time (t) on the coagulation of particles were investigated by monitoring particle counts in a rapid mixing process. Total particle counts after mixing of 30 s at G value of 200 s(-1) were similar to the summation of clay particles and alum precipitates at alum dose of 30 mg L(-1). Although small particles (microflocs less than 5 microm) were formed within the mixing time of 30 s, macroflocs larger than 8 microm did not increase significantly until the mixing time of 60 s. However, macroflocs larger than 8 microm started to increase after mixing of 75 s and they reached the maximum counts at 150 s. On the other hand, macroflocs larger than 8 microm decreased after mixing time of 180 s due in breaks of the macroflocs, which resulted in resuspension of small particles. The rapid mixing conditions for the maximum growth of macroflocs were the G value of 200 s(-1) and the mixing time of 150 s, which confirmed the best performance of turbidity removal in jar tests. Growth and break of particles and flocs in a rapid mixing step would influence significantly on the sequential flocculation and sedimentation processes for turbidity removal.

Immunogenicity and lower dose requirement of polymer entrapped tetanus toxoid co-administered with alum

Low adjuvanticity of microparticles based vaccine formulation necessitates the use of alum along with particles to elicit improved antibody titers from single point immunization. It was observed that antibody response from immunization with admixture of alum and polymer entrapped antigen was dependent on particle size, amount of antigen released during burst phase and dose of microencapsulated antigen. In the animals immunized with polymer entrapped tetanus toxoid (TT) very large particles (50–150 μm) did not elicited high antibody titers where as microparticles in the range 2–8 μm exhibited remarkable improvement in the antibody response. Very small size particles (<2 μm) were also not as effective as 2–8 μm size particles for generation of antibody response. Presence of alum improved the immune response by adsorbing the burst released antigen from the particle surfaces. Role of alum in potentiation of immune response from polymer entrapped TT was highly significant at lower dose regimes. Polymer entrapped TT as little as 0.1 Lf when immunized along with alum generated antibody responses superior to those elicited by 10 Lf soluble antigen. Immunization with admixture of particles and alum generated two to three times higher antibody titer than that observed from immunization with similar single doses of alum adsorbed TT. Single point immunization of admixture of particles entrapped TT and alum generated sustained long lasting antibody responses comparable to two divided doses of alum-adsorbed antigen. Superiority of single dose polymeric formulation in comparison to two divided doses of alum adsorbed TT was more evident at lower doses of TT immunization. This reflected the profound synergistic effect of both the adjuvants at lower doses. Affinity of antibodies generated from single point immunization was comparable to that achieved with two doses of alum adsorbed TT immunization. Particle alone elicited more of IgG2a type antibody where as immunization with admixture of alum and particles improved the overall antibody response and more of Th2 type response.

Feasibility study for reclamation of a secondary treated sewage effluent mainly from industrial sources using a dual membrane process

A feasibility study for reclamation of a secondary treated sewage effluent mainly from industrial sources (60%) in Singapore has been conducted using a dual membrane UF-RO process. The pilot system had a treatment capacity of 2 m 3/h. The UF unit and RO unit were operated at 70–80% and 40% water recovery, respectively. Six-month run for the pilot was carried out to study the stability and fouling tendency of membranes. The characteristics of the raw feed indicated that ammonia-N was consistently high at 30–50 mg/L. Very high fluctuations in iron (0.3–3.7 mg/L), turbidity (1–27.1 NTU) and TOC (3.2–56.7 mg/L) were observed. Nitrate was low at <0.2 mg/L. The results of the study showed that dosage of alum in the UF process significantly reduced organic foulants and phosphate scalants. The polymeric RO membrane could tolerate organics from industrial wastewater and performed >96% salt rejection at the end of the study after 6 months. The study concluded the dual membrane process was capable of reclaiming the sewage effluent mainly from industrial sources for industrial use.

The effects of filtration temperature and alum dosing on Cryptosporidium sized particle breakthrough

Understanding the causes of breakthrough in filtration is essential worldwide. Breakthrough links many factors, such as filtration flow rate and flow rate changes, temperature, chemical dosing, raw water quality, etc. These factors can affect floc strength, which has been recognized as one of the most important factors in filter efficiency and particle breakthrough, related to Cryptosporidium outbreaks. This research aims to investigate particle breakthrough related to temperature and chemical dosing. Experiments were conducted to establish the relationship between temperature and chemical dosing changes to floc strength and particle breakthrough. The temperature was set at a series range as 5 °C, 15 °C and 25 °C. Each was combined with a series of Al dose changes. A laser particle counter was installed to assess the particle breakthrough online. ζ potential and turbidity were measured before (after coagulation) and after filtration. The results show particle breakthrough is influenced significantly by temperature and dosing. Particle breakthrough increased rapidly at lower temperatures but at higher temperatures it reduced at the same coagulant dose. With coagulants, even at low doses, particle breakthrough reduced significantly. There is an optimal dose in filtration; the optimal dose gives a ζ potential equal to about zero.

板紙抄造系における硫酸バンドを削減したトータルウェットエンドシステム

製紙業界では近年，地球環境問題に対する配慮が必要不可欠になる一方で，収益改善を目的とした合理化，コストダウンを余儀なくされており，製紙工程の環境が急激に変化している。板紙に着目すると，雑誌古紙の配合比率が増加するなど原料事情が変化し，抄造系への炭酸カルシウムの混入量が増加する傾向にある。そのため，抄造系のpHが上昇し，それを抑えるために過剰な硫酸や硫酸バンドを使用している現状がある。また，石膏スケール問題が頻繁に発生したり，電気伝導度が上昇し内添薬品の効果が低下したりするなどの弊害が生じている。このような状況の下，板紙において硫酸バンドを削減しながら，いかに有効に使用するかを模索することが今後重要となる。硫酸バンドを減少するだけではデメリットも生じるが，トータル処方としてのウェットエンドシステムを適用すれば，それらのデメリットを解消できるだけでなく，相乗効果による品質向上が見込まれる。本報では硫酸バンド量を削減し，地球環境への配慮，品質向上，生産性の向上といった現代の板紙抄造が抱える課題を同時に解決することができるトータルウェットエンドシステムについて紹介する。

Filtration Removals of Microorganisms and Particles

Filtration log removals (logR’s) were determined by pilot plant seeding experiments for a selected array of organisms, i.e., protozoan cysts, algae, bacteria, and viruses, as well as turbidity/particles. Removals of these organisms and particles varied from one species to another within the range 1.4⩽logR⩽5.1 for “reference,” i.e., specified, conditions. For other conditions, called here “excursion” conditions, logR’s were found to be proportional to alum dose between zero and “optimum” the latter being defined as the smallest dosage that minimized filter effluent turbidity. Mono and dual media did not show performance differences, and conventional filtration showed slightly higher logR’s than in-line filtration. The influent concentration did not show a “true” effect on logR’s (but an “apparent” effect was seen when effluent values were consistently very low, making logR’s proportional to influent concentration). logR’s obtained in limited experiments at another site showed significant differences for two algae and two viruses when compared with logR’s for reference conditions. The results illustrate the logR variation that may be found among different groups of organisms/particles and indicate the influences of certain independent variables (e.g., influent concentration, dual media versus mono media, conventional filtration versus in-line, alum dose, zero alum dose, and filtration at a different site) on filtration removals. In addition, the importance of sampling repetitions was reinforced. The findings are significant to water treatment practice in that organism removals by filtration are likely to vary, depending on the organism/particle species as well as the filtration conditions. The implication is that a pilot plant study is advisable if confidence in logR is desired for a given organism/particle.

Impact of coagulation pH on enhanced removal of natural organic matter in treatment of reservoir water

Effect of coagulation pH on enhanced removal of NOM in treatment of reservoir water for drinking purposes has been investigated in this study. Raw water was collected at a local Waterworks of Singapore. Trials with different coagulation pHs and alum dosages were conducted in jar tests. NOM removal showed an up-and-down trend with increasing coagulation pH. The results showed that the optimum conditions for NOM removal were observed at a pH 5.2 and at alum dosage of 5 mg (Al)/L. NOM (in terms of DOC) removal of up to 45% and turbidity removal at 97% were noted during the tests conducted at the optimal conditions while NOM removal was 35% at the conventional coagulation pH 7.2. It was concluded that control of coagulation pH was critical for NOM removal in treatment of the reservoir water.

Performance evaluation of an inclined belt filter using coagulation/flocculation aids for the removal of suspended solids and phosphorus from microscreen backwash effluent

As environmental regulations become more stringent, environmentally sound waste management and disposal practices are increasingly more important in all types of aquaculture. In many recirculation systems, microscreen filters are used to remove and concentrate the suspended solids from the process water, because they require minimal labor and floor space and can treat large flow rates of water with little head loss. These microscreen filters generate a separate solids waste stream that can be further concentrated to reduce the quantity and improve the quality of discharge water. A Belt Filter System, Hydrotech Model HBF537-1H, from Waste Management Technologies Inc., Baton Rouge, LA, USA was evaluated for rapid thickening of sludge from the backwash water of a microscreen filter. When used in conjunction with coagulation/flocculation aids, significant reduction of suspended solid and phosphorus are possible. Testing of the system was conducted using the backwash effluent of a microscreen filter that treated water discharged from several large-scale recirculating aquaculture production systems growing artic char and trout. The system was tested using only alum as the coagulant aid, using only a commercially available polymer as the flocculation aid and the two coagulation/flocculation aids in combination.Alum alone was moderately efficient in removing solids (82%), but was very efficient in sequestering reactive phosphorus (96%), with effluent concentrations less than 0.07mg/L-P at the highest alum dosage tested, 100mg/L. Several commercially available polymers used alone and at relatively low dosages (15mg/L) were very effective in removing suspended solids, with a removal rate averaging 96% and with an effluent TSS concentration of less than 30mg/L. The polymers were not as efficient as alum in removing reactive phosphorus, with a removal rate of approximately 40%. At the optimum combined dosage of alum (mg/L) and polymer (mg/L), the Inclined Belt Filter System increased the dry matter content of the sludge to approximately 13% solids, and reduced both the suspended solids and reactive phosphorus concentration of the effluent by 95 and 80%, respectively. The combination of coagulation/flocculation aids and the inclined belt filter show excellent potential to greatly reduce the volume of solids generated, and significantly reduce the concentration of suspended solids and phosphorus in discharged effluents. By eliminating the need for settling tanks or ponds, the leaching of nutrients (phosphorus, nitrogen) is minimized and the dewatered sludge is in a form for easy transport, storage, or disposal.