• Journal of Korean Society of Water and Wastewater
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• v.35 no.4
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• pp.277-284
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• 2021

The ballasted flocculation effects of the mill scale and magnetite on activated sludge were investigated. Both ballasted flocculants (BF) could remarkably improve the sludge settleability in terms of zone settling velocity (ZSV) and sludge volume index (SVI). With the BF dosage of 0.2 to 2.0 g-BF/g-SS, the magnetite particles showed better efficiency on improving settling behavior of activated sludge than the mill scale due to higher surface area and hydrophobic property. The efficiency of SVI₃₀ with magnetite injection was 2.5 to 11.3% higher than mill scale injection and that of the ZSV appreciated from 23.7% to 44.4% for magnetite injection. Averaged floc size of the BF sludge with magnetite dosage (0.5 g-BF/g-SS) was 2.3 times higher than that of the control sludge. Dewaterability of the sludge was also greatly improved by addition of the BF. The specific resistance to filtration (SRF) was reduced exponentially with increasing the dosage of BF. However, the BF's particle size effect on the SRF looks to be marginal. Consequently, for improving the dewaterability, the BF played a physical role to remove the pore water of the biological flocs by intrusive attachment and a chemical role to induce aggregation of the flocs by charge neutralization.

• Resources Recycling
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• v.25 no.3
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• pp.3-10
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• 2016

The passive treatment was required a large area for the treatment of acid mine drainage (AMD), and pollutants were discharged with mine drainage by the increased flow rate in summer. This study was performed to improve the turbidity and to precipitate the pollutants quickly using coagulants and flocculants in AMD of abandoned mine sites that were difficult to build the passive treatment system. The coagulant PAC (Poly aluminium chloride) and flocculant PAM (Polyacrylamide) were selected to improve turbidity in W mine waters. We also tested the particle size analysis, ICP-OES and/or SEM-EDS for water and sludge samples.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.2
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• pp.136-146
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• 2007

Landfill leachate was successfully treated in upflow anaerobic sludge blanket (UASB) reactors regardless of the addition of granular sludge. Initial operating period was significantly reduced by the addition of granular sludge. At hydraulic retention time (HRT) of one day, chemical oxygen demand (COD) removal rates in Control and Granule reactor were maintained over 90%, respectively with organic loading rate (OLR) of $4-8kgCOD/m^3.d$. During the experiment, the inorganic precipitates were accumulated in and around the sludge, and in the wall of the reactors were formed in both reactors regardless of addition of granular sludge. Specific methanogenic activity (SMA) increased as adaptation of microorganism to the substrate and OLR were increased. The maximum SMA value of the sludge for Granule reactor was about $0.57gCOD/g{\cdot}VSS{\cdot}.d$. The SMA value was not decreased because of excessive inorganic accumulation, however, it was needed to have pre-treatment process of influent to remove the inorganic metals.

• Journal of the Korea Organic Resources Recycling Association
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• v.28 no.3
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• pp.15-26
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• 2020

To recover phosphorus from incinerated sewage sludge ash(ISSA), ISSA were extracted with sulfuric acid solution, and the optimal phosphorus recovery conditions were experimented by comparing the recovered phosphorus contents and heavy metals by raising pH. Also the phosphorus recovery efficiency was compared when acid extract was reused or classified by particle size of ISSA. The optimal conditions for recovering phosphorus from ISSA were 1N sulfuric acid solution with an L/S ratio of 10, and an extraction time of 30 minutes. Considering the addition of alkali substances and the content of heavy metals in the recovered sediment, it is concluded to recover phosphorus under pH 5. Reuse of the ISSA extract increased the recovery rate of phosphorus by 14~21% depending on the reuse rate (100 and 50%), but it also increased zinc contents to 33 and 21%, and copper contents to 35 and 20%, respectively. The experiment of ISSA divided into four sections by particle size showed that there was no distinct advantage of phosphorous recovery by classification of certain particle size of ISSA. The removal of heavy metals from extracts through EDTA and cation exchange resin showed no definite effect.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.3
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• pp.21-29
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• 1985

An effective technique of sludge separation is required for concentrated activated sludge process. The dissolved-air flotation (DAF) has been shown to be efficient process for sludge separation. The factors affecting DAF process for activated sludge separation are type and concentration of sludge, air/solid ratio, ratio of pressurized water flow, pressure, sludge detention time, temperature, sludge and hydraulic loading rate, recycle flow rate of sludge and type and quantity of chemical aid. In order to study the optimal operation condition for sludge separation, the influence factors such as type and concentration of sludge, ratio of pressurized water flow and pressure are investigated by the batch and continuous reactor experiments of DAF and sedimentation test. By the experimental investigation, the results are as follows; 1. For the bulking and concentrated sludge, DAF is more effective than sedimentation for the sludge separation. 2. In DAF, the critical ratio of pressurized water flow exist. The critical value varies with the pressure in the tank. That is, according to the pressure changes from 3 to $5kg/cm^2$, the critical value varies from 0.25 to 0.67 accordingly. 3. Pressure affects the ratio of pressurized water flow, but it does not show any influence upon the DAF efficiency directly. 4. Continuous experimental results was not better than those of batch.

• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.69-75
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• 2010

Total suspendid solid (TSS) of non point source pollutants in construction site are in higher concentration than others (BOD, COD etc). Also, the TSS concentration is very sensitive to the rainfall intensity in early stage of construction. There are two methods for treatment of non point source pollutants, which are temporary treatment facility and filtering one. But they have disadvantages. Temporary facility system has very low efficiency and filtering system consumes high energy and takes up large footprint. This study shows how prefabricated flocculation/coagulation system is developped to cover the above weakness and evaluation of the system performance in construction site. The prefabricated flocculation/coagulation system has very high treatment efficiency comparing with temporary and filtering system and takes small footprint. Therefore, it expects that the system leads to prevention of pollution near construction site and reduction of public grievance. Proper coagulant dosage and sludge circulation facility application, controlling the height of sludge interfacial are necessary to maximize the system efficiency.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.679-688
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• 1994

Physicochemical and morphological characteristics of biopellets produced in "control" and modified UASB reactor were investigated to compare the reactor performance with regard to the hydrogen partial pressure. The characteristics of biopellet produced in modified UASB reactor operated with high hydrogen partial pressure were better than those of "control" reactor operated with relatively lower hydrogen partial pressure, therefore the hydrogen partial pressure effected greatly on the formation and stability of the biopellet. Furthermore, pellets from the UASB system with modified settler showed a better settleability and biomass holding capacity. The chemical composition of biopellet was distinctively different from that of common bacterial formula, $C_5H_7O_2N$. Biopellets was composed the large fraction of nitrogen in comparison with common anaerobic microbes. These results implicated the existence possibility of polypeptide-type extracellular polymer. The morphological characterization with SEM showed that microorganisms observed at surface of biopellet produced in modified UASB reactor operated with high $P_{H_2}$ condition were very similar in shape and size to the Methanobrevibactor arboriphilus-$H_2$ utilizing methanogen. The microorganisms was distinguished from those of "control" reactor operated with low $P_{H_2}$ condition. From these results, it could be explained the hydrogen partial pressure effects on pelletization mechanism.

• Journal of Environmental Science International
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• v.15 no.12
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• pp.1177-1183
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• 2006

This study was carried out to evaluate effect of sludge characteristics (pH, SVI, anaerobic storage, wet density and growth phase) on the sedimentation of bulking sludge of paper manufacturing plant. The results showed that mix hulking sludge with sewage sludge (10-60%) caused the decrease of SVI, the settled sludge concentration was increased. Increase of anaerobic storage time (0 to 8 day) was increased SVI, sedimentation performance was deteriorated. The sedimentation was improved by addition of loess (0.2-5.0 g/L), because wet density of sludge was increased and SVI was decreased. At an exponential phase, the ratio of sedimented/growthed sludge concentration was decreased, the ratio was increased after stationary phase.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.694-702
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• 2013

The purpose of this study is to evaluate a de-watering filtrate treatment and the possibility of securing biological treatment capacity by changing the structure of the secondary clarifier. Accordingly, the column test was conducted to determine the effect of polymer in the de-watering filtrate on sludge sedimentation. Also, the characteristics of de-watering filtrate processing was evaluated through batch test and continuous processing operation. The results showed that sludge settling velocity increased with higher polymer concentration, and that effluent SS concentration was found to decrease. Regarding processing characteristics of de-watering filtrate, the removal efficiency of TSS and TBOD5 increased as the length of secondary clarifier was longer. Also, comparing injections into anoxic tank and secondary clarifier, de-watering filtrate by continuous infusion treatment process showed stability in both conditions. Therefore, by modifying the structure of secondary clarifier, efficient processing of de-watering filtrate is expected to be possible and processing capacity of small sewage treatment plants is considered to be improved.

• Journal of the Korean GEO-environmental Society
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• v.12 no.5
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• pp.51-57
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• 2011

Generally, ready-mixed concrete(RMC) gets hardened by time, so the remaining concrete in the drum should be cleaned. But if the RMC waste water generated from this is discharged to soil without any treatment, the strong alkaline elements and heavy metals affect water and ecosystem pollution. Although about 10 to 15% of water used for cleaning in the RMC factory is discharged to soil or river, the concrete report of this affecting soil pollution has not been sufficient. Hence, in this study it was analyzed the extraction of cleaning water from RMC factories all over the country and heavy metal and pH components remaining in soil when this is penetrated to various soils having water permeability. The specimens used for the experiment are weathering soil and soils having different particle size, and it is made to be penetrated to those for 24 hours while fixed thickness of the layer is maintained. Cleaning water is divided into that before deposition treatment(sludge water) and that after deposition treatment(upper water) to be penetrated into soil, and according to the result of penetrating sludge water to soil, Cu and Mn, Fe, and Zn were found to be remained over 23 to 90%. However, it is analyzed that in upper water having deposition treatment, Cu and Mn remain as 60% or more only in weathering soil.