Blanket Process Research Articles

Cost-effective Treatment Technology on Textile Industrial Wastewater in Bangladesh

To minimize the cost effective treatment process a treatment process has been setup at Dalas Fashion Ltd and Liz Fashion Ltd, Gazipur, Dhaka. The treatment process consisted of a combined process (anaerobic and bio-filtration process) to remove the pollution through biological process. The anaerobic process followed by Up-flow Anaerobic Sludge Blanket (UASB) process and Bio-filtration was maintained by polyurethane materials followed by down-flow process. The treatment processes are successfully operating without any chemical treatment process being thus more economic than the traditional chemical alternative. The raw textile wastewater is highly polluted with the characteristics of high alkaline in nature, pH=9-10, suspended biomass TSS= 1229-1500 mg/l, Chemical oxygen demand, CODt = 1448-2000 mg/l, and biological oxygen demand, BODt= 550-800 mg/l. Significant reductions were achieved to remove TSS (98%) through bio-filtration process. In addition in the final effluent the removal efficiency were found CODt (98%), BOD (94%) and color were removed significantly. Total cost taka 89.84 million per year for the chemical ETP process. On the contrary, for UASB ETP requires a total cost taka 17.84 million per year. DOI: http://dx.doi.org/10.3329/jce.v27i1.15855 Journal of Chemical Engineering, IEB Vol. ChE. 27, No. 1, June 2012: 32-36

Assessment of anti-fouling strategies for membrane coupled with upflow anaerobic sludge blanket (MUASB) process

In this novel process, domestic wastewater was filtered by a hollow-fibre membrane coupled with an upflow anaerobic sludge blanket (MUASB) bioreactor. To improve the process sustainability and decrease energy costs, the membranes were operated under low fluxes with little, or no, shear. The efficiency of anti-fouling strategies, including relaxation, backwashing and supply of low aeration and stir rates, was assessed through detailed characterization of the fouling layers. Results indicated that backwashing was more efficient than relaxation, even when the systems were operated under the same flux productivity. In terms of shear supply, stir provided a better fouling limitation strategy compared to aeration, at similar shear stress values. Physical and chemical cleaning methods were applied to recover three fouling fractions (i.e. cake, residual and irreversible) for better characterization of the fouling layers. Under the sustainable operating conditions used in this study, most of the fouling was easily reversible by simple rinsing. In addition, permanent and irreversible fouling, resulting in the need for frequent chemical cleanings and potential membrane degradation, is limited once small shear stresses are applied. These outcomes are expected to form the basis for the future assessment of trade-off between operation, maintenance and replacement costs of membrane filtration processes used in wastewater treatment.

Toponyms and the Political and Ethnic Identity in Serbia

In the course of the last 150 years about 25 place-name changes have taken place in Belgrade. Some were more significant than others, and some of the renamed places have suffered as many as six name changes. These changes are part of a blanket process that includes renaming of state administration institutions, research institutes, schools, universities, factories, museums, sport clubs, etc., as well as personal names. This process reflects political, economic, demographic, and cultural changes serving the purpose of constructing and reconstructing political, ethnic, religious, and cultural identity, as well as political relations, and history. In this paper the author discusses this renaming process, its causes and consequences, as well as its potential for constructing and reconstructing reality.

The application of UASB-MBR with partial nitrification-denitrification in wastewater reclamation in warm climate

An up-flow anaerobic sludge blanket (UASB) process has been successfully applied for the treatment of municipal wastewaters with methane production for energy recovery. A membrane bioreactor (MBR) was coupled to the UASB to further improve carbon removal. Nitrogen removal was conducted with the UASB-MBR integrated system under optimum conditions which promoted nitrogen removal through a shortcut nitrification-denitrification process. The process achieved 69–86% of soluble chemical oxygen demand (CODsolu) removal and 56–80% of total nitrogen (TN) removal. Biogas production was between 25 and 76 L/m3 wastewater (50–75% methane content) for the treatment of high-strength municipal wastewater. As the anaerobic process combined with a shortcut nitrogen removal step can achieve reduction of footprint, lower greenhouse gas emission and a potential for bioenergy recovery, the integrated UASB-MBR system could be a better choice for municipal wastewater treatment than the conventional activated sludge treatment process in warm climatic conditions.

Toxicity and treatability of leachate: application of UASB reactor for leachate treatment from Okhla landfill, New Delhi

This study reports applicability of upflow anaerobic sludge blanket (UASB) process to treat the leachate from a municipal landfill located in Delhi. A laboratory scale reactor was operated at an organic loading rate of 3.00 kg chemical oxygen demand (COD)/m(3) d corresponding to a hydraulic retention time (HRT) of 12 h for over 8 months. The effect of toxicity of leachate, and feed composition on the treatability of leachate was evaluated. Average COD of the leachate, during the study period varied between 8,880 and 66,420 mg/l. Toxicity of the leachate used during a period of 8 months varied from LC50 1.22 to 12.35 for 96 h. The removal efficiency of soluble COD ranged between 91 and 67% for fresh leachate and decreased drastically from 90 to 35% for old leachate having high toxicity. The efficiency varied from 81 to 65%. The reactor performed more efficiently for the treatment of fresh leachate (less toxic, LC50 11.64, 12.35, and 12.15 for 96 h) as compared with old leachate (more toxic, LC50 1.22 for 96 h). Toxicity of the leachate affected its treatment potential by the UASB.

Sequential treatment of PTA wastewater in a two-stage UASB process: Focusing on p-toluate degradation and microbial distribution

Two-stage upflow anaerobic sludge blanket (UASB) process was investigated as an efficient process configuration option for the treatment of purified terephthalic acid (PTA) wastewater. To study its feasibility in a defined condition, synthetic wastewater containing only the major pollutants (i.e., acetate, benzoate, terephthalate and p-toluate) was used. By focusing the role of the second stage on the p-toluate degradation, improved overall COD and p-toluate removal capacities of 4.18 and 1.35 g-thCOD/L·day could be achieved together with a complete COD removal efficiency. In this situation, all the pollutants except p-toluate were completely degraded in the first stage while 38 and 62% of p-toluate originally present in the wastewater were consecutively degraded in the individual stages. The concomitant methane production rate in each stage was 0.91 and 0.35 L/L·day respectively, and the methane yield on p-toluate was determined to be 0.12 L/g-thCOD. Batch tests using the granules obtained from each stage revealed that the acidogenic microorganisms enriched in both stages had a universal ability to degrade all aromatic pollutants present in the PTA wastewater. Moreover, image analysis using scanning electron microscope and confocal laser scanning microscopy combined with fluorescence in situ hybridization technique elucidated that the distribution of acidogens and methanogens within the granule was varied in each stage, which influenced the mass transfer regime resulting in the different pollutant degradation rates during the batch tests.

Direct Treatment of Settled Sewage by DHS Reactors with Different Sizes of Sponge Support Media

The down-flow hanging sponge (DHS) reactor, which was developed for post-treatment of effluent from up-flow anaerobic sludge blanket (UASB) process treating sewage, uses polyurethane sponge as media to retain biomass. Wastewater is trickled from the top of the reactor and purified by microorganisms retained both inside and outside of the sponge media as the wastewater flows vertically down through the reactor. Three DHS reactors employing different sizes of sponge media with the same total sponge volume were used for the direct treatment of settled sewage. All the reactors exhibited excellent performance in removal of COD, ammonium nitrogen, and fecal coliform at a fixed hydraulic retention time of 2.0 h based on the sponge volume. It was shown that smaller sponge media produced better removal efficiencies for all the parameters listed above. The most reasonable explanation for this might be that smaller sponge media allows better oxygen uptake in the stream flowing down through the reactors.

Evaluation of Treatment Characteristics and Sludge Properties in a UASB Reactor Treating Municipal Sewage at Ambient Temperature

The evaluation of treatment characteristics and sludge properties of an upflow anaerobic sludge blanket (UASB) process was investigated using a pilot-scale 1.15 m 3 reactor. The UASB, inoculated with digester sludge, was operated at a hydraulic retention time of 8 h at sewage temperatures ranging from 10.6 to 27.7 °C for more than 1100 days. The stable removal efficiencies for total COD Cr and SS were 63 ± 13% and 66 ± 20%, respectively. The average concentration of the retained sludge increased to more than 24.5 gSS/L of the column volume after two years of operation. In summer, the water temperature increased above 20 °C, and biodegradation of solid organic matter was enhanced. The solid retention time was evaluated to be as long as 293 ± 114 days; this is sufficient for mineralisation of solid organic matter, as indicted by a low sludge conversion of 0.029 gVSS/gCOD removed and a growth yield of 0.132 gVSS/gCOD, determined by seasonal sludge profiling. The bacterial communities, based on bacterial 16S rRNA genes in the retained sludge, were significantly diverse. Bacteroidetes and Firmicutes were the dominant phyla of the decomposers of solid organic matter in the library. A Ruminococcus-related clone detected in the Firmicutes phylum acted as a cellulose decomposer. Key word: Anaerobic, UASB, Municipal sewage, Ambient temperature,Sludge

Pilot scale evaluation on ferric floc sludge concentration with pelleting flocculation blanket process

Pelleting flocculation blanket (PFB) process has been successfully applied to high turbidity suspensions for high efficient solid/liquid separation. In this paper, by using the PFB process, a dynamic experimental study was carried out on concentrating ferric flocs sludge with a scale of 1.3-5.4 m(3)/h. The pilot experiment aimed to optimize the conditioning system and determine the operational parameters. Under the raw sludge concentrations of 103-1,154 mg/L, the system could achieve ideal conditioning effect with polyacrylamide (PAM) dosages of 0.3-2.7 mg/L, agitation speed of 10 rpm, and water up-flow rates of 18-48 m/h. Under the experimental conditions, the increase of polymer dosage would improve effluent turbidity and pellets settling behaviour, the moderate up-flow rate had no marked effect on treatment results, while too large surface loading could worsen effluent turbidity. The experimental results also revealed that there existed an approximately linear relationship between the raw sludge concentration and optimum PAM dosage, that is, the optimum dosage of PAM increased synchronously as the raw sludge concentration increased. While the relationship between the raw sludge concentration and maximum up-flow rate reflected another linear dependence, namely, the maximum up-flow rate would decreased linearly as the raw sludge concentration increased.

Settling behaviour of pellet flocs in pelleting flocculation process: analysis through operational conditions

Pellet flocs' settling velocity is an important parameter in the pelleting flocculation blanket (PFB) process, hence, it is necessary to investigate flocs' settling behaviour to achieve the optimum operation parameters of the process. To investigate the settling behaviour of pellets under different operational conditions, a dynamic experiment was carried out to concentrate ferric flocs sludge by pelleting flocculation blanket (PFB) process with the scale of 0.5-1.2 m3/h. Under different operating conditions such as raw water concentration, polyacrylamide (PAM) dosage, up-flow rate, and agitation speed, pellet particles were sampled from different locations of the blanket in various operating stages to analyze pellet size, setting velocity, and porosity. Experimental results indicated that, when the PAM dosage increased from 0.59 mg/L to 1.18 mg/L, pellets size would flocculated from 2.25 mm to 3.52 mm with the settling velocity accelerated from 3.28 mm/s to 7.37 mm/s, while under the same up-flow rate, agitation intensity and PAM dosage, accompany with the raw water concentration increased from 216 mg/L to 840 mg/L, pellets settling velocity would improved from 6.03 mm/s to 13.6 mm/s. Under the experimental condition, along with the up-flow rate increased from 13.3 m/h to 40 m/h, pellets settling velocity would decreased from 4.39 mm/s to 3.42 mm/s due to its lower density.

Herbal pharmaceutical wastewater treatment by a pilot scale upflow anaerobic sludge blanket (UASB) reactor

Herbal pharmaceutical industry has grown tremendously in the last few decades. As such, literature on the treatment of this wastewater is scarce. Water pollution control problems in the developing countries need to be solved through application of cost effective aerobic/anaerobic biological systems. One such system-the upflow anaerobic sludge blanket (UASB) process which is known to be cost effective and where by-product recovery was also feasible was applied for treatment of a high strength wastewater for a period of six months in a pilot scale upflow anaerobic sludge blanket (UASB) reactor with a capacity of 27.44 m(3). Studies were carried out at various organic loading rates varying between 6.26 and 10.33 kg COD/m(3)/day and hydraulic retention time (HRT) fluctuating between 33 and 43 hours. This resulted in chemical oxygen demand (COD), biochemical oxygen demand (BOD) and suspended solids (SS) removal in the range of 86.2%-91.6%, 90.0%-95.2% and 62.6%-68.0% respectively. The biogas production varied between 0.32-0.47 m(3)/kg COD added. Sludge from different heights of UASB reactor was collected and subjected to scanning electron microscopy (SEM). The results indicated good granulation with efficient UASB reactor performance.

Anaerobic treatment of Hong Kong leachate followed by chemical oxidation

Landfill leachate of Hong Kong was first treated by the upflow anaerobic sludge blanket (UASB) process. At 37 degrees C, pH 7.1-8.5 and a HRT of 5.1-6.6 days, the process removed 66-90% of COD in the leachate for loading rates of 1-2.4 g-COD/l day depending on the strength of landfill leachate. The final effluent contained 1440-1910 mg-COD/l and 70-91 mg-BOD/l. About 92.5% of the total COD removed was converted to methane and the rest was converted to biomass with an average net growth yield of 0.053 g-VSS/g-COD-removed. The granules developed in the UASB reactor were 0.5-1.5 mm in size and exhibited good settleability. The UASB effluent was then further polished by two oxidation processes. The UASB-ozonation process removed 93.0% of the 12900 mg/l of COD from the raw leachate. The UASB-Fenton-ozonation process improved the COD removal efficiency to 99.3%. The final effluent had only 85 mg/l of COD and 10 mg/l of BOD5. Ozonation was most effectively conducted at pH 7-8 with the addition of 300 mg/l of H2O2 and for the duration of 30 min. Ozonation also significantly improved the biodegradability of the organic residues. Nearly 50% of these residues could be used as carbon source in denitrification.

Treatment of phenol and cresols in upflow anaerobic sludge blanket (UASB) process: a review

Upflow anaerobic sludge blanket (UASB) process has been successfully applied in the treatment of municipal and industrial wastewaters. Several researchers have investigated the suitability of the process for the treatment of phenols and phenolic wastewaters. The anaerobic treatment of phenols is still at an investigative stage. With increasing recognition of the UASB process, feasibility studies on the treatment of wastewater containing phenol and cresols (o-, m- and p- isomers) in UASB have been reviewed. It is reported that phenol concentration up to a range of 500-750 mg/L is generally not inhibitory to the UASB process. Phenol concentrations greater than 500 mg/L can be effectively treated with acclimatization of inocula, recirculation of the treated effluent and/or supplementing with co-substrates such as glucose, VFA and dilute molasses. The degradability of phenol is more than p-cresol, which in turn is more than m- and o-cresol.

Cost-effective solutions for sewage treatment in developing countries - the case of Brazil

Cost-effective solutions are a must in developing countries, not only regarding investment costs, but also in respect to technology and operating practices. With these two goals in mind, in Brazil a particular effort has been directed for the development and application of the Chemical Enhanced Primary Treatment (CEPT) process and of the Upflow Anaerobic Sludge Blanket (UASB) process, both followed by complementary secondary treatment. Both technologies are under current expansion in Brazil. Large CEPT plants have been designed and built, up to 3.7 m3/s average design flow, as well as large UASB reactors, up to 3.0 m3/s average design flow. The applied technologies are cost-effective: they present low investment and efficiencies of BOD removal of up to 50% to 70%. They allow the plant construction in steps, an initial phase with efficiency over the usual primary treatment, and in order to achieve best effluent quality and meet legal water quality standards, a logic upgrade post-treatment can later on be implemented. The higher initial reduction of BOD and TSS also permits savings in construction and operational costs of secondary treatment, due to lower organic load and lower energy consumption. Sludge represents a particular point of attention: in the cases when the CEPT was used, Chemical Stabilisation of the Sludge (CSS) has also been practiced, eliminating the high construction costs of the digesters, all the plant staying chemically operated. In the cases when the UASB is used preceding secondary treatment, sludge can easily return to the anaerobic vessel, the costly sludge digestion unit being avoided. UASB reactors have practically no equipment in the anaerobic vessel, no energy consumption, low sludge production, and when applied in hot climates as in Brazil, heating devices are not required. The Brazilian experience, some particular cases, special comments on design and different secondary treatment processes are presented in this paper, as a contribution to the discussion of cost and benefits, a prime point to be considered.

Effects of Stressed Loading on Startup and Granulation in Upflow Anaerobic Sludge Blanket Reactors

The successful operation of an upflow anaerobic sludge blanket (UASB) process depends on the formation of settleable and active granular sludge. As the anaerobic bacteria are slow-growing microorganisms, a common problem encountered in UASB operation is the long startup period and the development of biogranules. In the present study, an unconventional approach to accelerate startup and granulation processes in UASB reactors has been developed by stressing the organic loading rate (OLR) without having to reach steady-state conditions. Three UASB reactors treating a synthetic feed with chemical oxygen demand (COD) of 2,500 mg/L, at a mesophilic temprature of 35°C were studied. One reactor (R1) served as a control, while the other two (R2 and R3) were operated at different stress levels upon reaching COD removal efficiency of 75 and 85%, respectively. Experimental results indicated that under stressed loading conditions, the startup, and granule development were accelerated by 45 and 33%, respectively, along...

Effects of organic loading and oil-grease for the treatment of edible oil effluent in a pilot-scale upflow anaerobic sludge blanket process : Saatci, Y. et al. Int. J. Environment and Pollution, 2002, 18, (3), 301–308

Effects of organic loading and oil-grease for the treatment of edible oil effluent in a pilot-scale upflow anaerobic sludge blanket process : Saatci, Y. et al. Int. J. Environment and Pollution, 2002, 18, (3), 301–308

Sustainable Water Conservation and Wastewater Reuse in a Palm Oil Mill: A Case Study in Southern Thailand

Abstract The palm oil industry is one of the major agro-industries in Southern Thailand. It requires a large amount of water for its operation and discharges considerable quantities of wastewater. This creates a serious threat to the environment and sources of potable water. This study proposes recommendations for water conservation and reuse and improvement of wastewater treatment facilities to overcome these problems. In order to attain the highest reduction of all problems, waste minimization is introduced as the most effective solution. Changing behaviour in housekeeping can reduce water usage. An upflow anaerobic sludge blanket (UASB) process coupled with an activated sludge plant is recommended to upgrade the wastewater treatment system. For water reuse purposes, a rock bed filtration unit is recommended to treat effluent of the treatment plant. The overall water balance of the palm oil mill suggests that water reuse of 322 m3/d will reduce raw water consumption by 27.66% and achieve a 23% reduction in the water discharged to the river.

高温嫌気性廃水処理汚泥から分離したプロピオン酸酸化共生細菌の生理学的特徴とグラニュール汚泥内空間分布

A propionate-oxidizing microorganism in the methanogenic granular sludge from a thermophilic (55°C) upflow anaerobic sludge blanket (UASB) process was studied by cultivation and in situ hybridization analysis. To isolate the propionate-oxidizing anaerobe, primary enrichment was made with propionate as the sole carbon source under anaerobic conditions at 55°C. After several attempts to purify the propionate-oxidizing microorganism, we finally isolated a thermophilic, syntrophic bacterium that was able to oxidize propionate in syntrophic coculture with Methanothermobacter thermautotrophicus (“Methanobacterium thermoautotrophicum”) strain ΔH. This syntrophic propionate-oxidizing bacterium, designated as strain SI, oxidized propionate as well as ethanol, lactate, 1-butanol, 1-pentanol, 1,3-propanediol, 1-propanol and ethylene glycol in syntrophic coculture. In addition, strain SI fermented pyruvate and fumarate in pure culture. The spatial distribution of strain SI in sludge granules was investigated by fluorescence in situ hybridization (FISH) with a 16S rRNA-targeted oligonucleotide probe specific for strain SI in combination with confocal laser scanning microscopy. Using these methods, strain SI was shown to be present in the middle and inner layers of the thermophilic granules and it was juxtaposed with hydrogenotrophic methanogens. In addition, strain SI-type cells were found to account for 1.1% of the total cells in the sludge by the FISH-direct count method. These results indicate that strain SI may be responsible for propionate oxidation in situ as one of the significant populations in sludge granules.

Effects of organic loading and oil-grease for the treatment of edible oil effluent in a pilot-scale upflow anaerobic sludge blanket process

In this study, Karadeniz Birlik Dogan Erdil vegetable oil factory, Elazig City, Turkey, was selected as representative of this sector. During the first part of the test programme, the quality of raw effluents was investigated. The removals of COD and oil-grease were above 85% at organic loadings between 1.62 and 7.83 kg COD m-3 d-1 at hydraulic retention times of 2.0 and 2.5 days. The conversion rates of the removed COD into methane gas were between 0.24 and 0.361 g CH4 (g COD)-1.

Upflow anaerobic sludge blanket treatment of starch wastewater containing cyanide.

Treatment of tapioca starch wastewater containing cyanide using an upflow anaerobic sludge blanket (UASB) process was investigated. Sludge from an anaerobic lagoon treating tapioca starch wastewater was used as seed. Performance of the UASB reactor with influent cyanide concentrations up to 25 mg/L was assessed. The inhibitory effects of cyanide were temporary and reversible. The process required longer recovery period for higher cyanide dosage. For 25 mg/L of cyanide concentration in the feed, the reactor required 15 days for complete recovery. Process performance was sensitive to operating parameters such as upflow velocity, cyanide loading rate, and chemical oxygen demand (COD) loading rate. A maximum cyanide loading rate of 0.38 kg/m3 x d was achieved in the process at a COD loading rate of 50 kg COD/m3 x d. Experiments with tapioca starch wastewater containing up to 10 mg/L of cyanide yielded satisfactory cyanide removal of approximately 93 to 98% and gas productivity of 7.5 m3/m3 x d with a COD loading rate of 30 to 40 kg COD/m3 x d.