• 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.

• Clean Technology
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• v.24 no.2
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• pp.87-98
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• 2018

Phosphorus (P) is an essential and irreplaceable element for all living organisms, and it is widely used as a fertilizer. Unfortunately, it is estimated that phosphate reservoir is depleted within about 100 years. Sewage sludge ash (SSA) is an alternative resource for P recovery because of its high P content. However, SSA cannot be directly used as a fertilizer due to heavy metals in it and low P bioavailability. Thermochemical treatment with Cl donor is known to reduce heavy metal contents and increase P bioavailability of SSA. Literature review on thermochemical technologies of SSA for the reduction of heavy metals and bioavailability enhancement has been carried out to estimate the status of current P recovery technology and to develop strategic future research plan for P recovery. The review showed that $CaCl_2$ and $MgCl_2$ were the most effective Cl donors and reaction temperature (< $1000^{\circ}C$) was the critical operation condition for the reduction. The removal efficiency depends on the species of heavy metals. Thermochemical technology of SSA for P recovery showed the possibility of commercial application in the near future to overcome the coming crisis of human sustainability by P depletion, but it needs cost effectiveness and more ecofriendly process to reduce energy consumption.

• Journal of the Korea Organic Resources Recycling Association
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• v.29 no.1
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• pp.5-17
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• 2021

This study is a literature review on the recovering phosphorus from Incinerated Sewage Sludge Ash(ISSA), which has relatively high content of phosphorus. Experimental conditions and influencing factors related to the recovery of P and removal of heavy metals by wet and thermochemical methods were discussed. For the practical application of the recovery of P from ISSA, an integrated process linked to incineration facilities is required in terms of economy from the perspective of the entire system including disposal of wastewater and residues generated during the recovery process, and minimizing added chemicals and energy consumption.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.1
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• pp.29-37
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• 2018

In this study, optimum extraction conditions for phosphorus recovery from sewage sludge ash(SSA) were investigated. For this purpose, an experiment was conducted to determine optimal recovery conditions for Ca-P type phosphorus by using calcium component in the recycled aggregate residue. The phosphorus content of sewage sludge ash was confirmed to be 5.0 %. When $H_2SO_4$ was used as an extract, concentration of 1 N $H_2SO_4$, L/S ratio of 10, and extraction time of 30 min were found to be the optimal extraction conditions. Phosphorus was extracted by using optimal extraction conditions, and then the heavy metals eluted with phosphorus were removed using 1~20 g of cation exchange resin. In 20 g of cation exchange resin, Fe 71.3%, Cu 82.4%, Zn 79.9%, and Cr 15% were removed. After that, the mixing ratio of the calcium extract obtained from the recycled aggregate residue (RAR) was changed to 1:1, 1:5, 1:10. The pH of the SSA to RAR mixture was adjusted to 2, 4, 8 and 12 by the addition of 5 N NaOH to the mixture of 1:5, and the phosphorus was recovered as Ca-P type precipitate. The optimum pH was 8. When recycled aggregate residues were used, the weight of calcium phosphate increased, but the amount of wastewater generated also increased. Therefore, it was concluded that the use of recycled aggregate residue was not economically feasible.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.1
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• pp.40-49
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• 2017

In this study, we have made the annual total phosphorus (TP) mass balance diagrams for I wastewater treatment plant by utilizing the data of flow rate and TP of each process and tried to choose the optimum unit process empirically for phosphorus recovery. For the applicability evaluation, we have suggested several quantitative indices of flow rate, TP concentration, TP load and SS. Based on the analyses of TP mass balance, it became clear for reducing TP load of the wastewater treatment plant that it is efficient to recover phosphorus from the side stream in which the amount of flow rate is just 1/16, but TP concentration and load are 78 and 4.8 times larger than those of the influent of the plant. After the detailed applicability evaluation for the side stream, it could be concluded that the unit process of waste activated sludge thickener supernatant or dehydration filtrate are appropriate. Meanwhile, we did fundamental experiments utilizing the dewatering filtrate with TP concentration of 141.5 mg/L. After adjusting pH 10 and $Ca^{2+}$ concentration 250, 500, 1000 mg/L, it was stirred slowly. As a result, the $PO_4-P$ and TP removal efficiencies were above 95 percent; the results of the experiment imply the applicability of phosphorus recovery process in a wastewater treatment plant strongly.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.557-564
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• 2009

The objective of this study is to efficiently recover phosphorus contained in sewage sludge by a struvite-forming method. The performances were evaluated under various operating conditions(elution with the kind of acid, Mg-compound and temperature) in order to reach the optimum conditions of struvite-forming. As a result, as an elution solution, the elution efficiency of $H_2SO_4$ was 2.65 times higher than that of HCl. Also, the precipitation efficiency of struvite was the highest (97.4%) in case of using $MgCl_2{\cdot}6H_2O$ as Mg-compounds at $25^{\circ}C$. However, the side reaction by Fe, Al and Zn appeared in process of phosphorus recovery. To solve some problems caused by side reacton, large quantities of co-precipitation materials produced by side reaction were removed by precipitating phosphorus compounds in pH 7. Consequently, the recovery efficiency of phosphorus by a struviteforming method was 82.99%, and purity of the recovered struvite product was high.

• Journal of Animal Environmental Science
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• v.12 no.2
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• pp.95-100
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• 2006

This study was carried out to develop a continuous process for recovering phosphorus in swine slurry. Magnesium chloride ($MgCl_2$) was used in the test as a magnesium source and the pH was regulated by adding NaOH and aerating. The results showed that the recovery rate of soluble phosphorus (SP) has increased with the molar ratios increased. In case of pH regulated with NaOH, the recovery rates of SP with molar ratio of 1:1.5 were over 95% from both farms. The removal of ammonia-nitrogen was at levels of $4{\sim}9%$. With aeration treatment, the SP recovery rate was 66% and the removal rate of ammonia-nitrogen was 15%. The treatment of NaOH to increase pH showed better SP recovery efficiency than the aeation treatment. However, in case of ammonia-nitrogen removal, the treatment of aeration showed better results than the NaOH treatment.

• Proceedings of the Korean Environmental Sciences Society Conference
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• 2006.05a
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• pp.363-369
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• 2006

본 연구의 목적은 하수슬러지로부터 외부탄소원을 회수하여 하수의 질소 및 인 처리를 위한 최적의 pH선정과 감마선 조사의 적용가능성을 조사하는 것이었다. 연구 결과, 외부탄소원의 회수 가능성을 평가할 수 있는 index인 SCOD의 값은 비조사된 하수슬러지에서는 pH13에서 SCOD 간이 6590mg/L이고, 가용화율 SCOD/TCOD값은 57.8%로 최대의 탄소원을 회수할 수 있음을 확인하였고, 동일 pH에서는 경우에는 조사선량이 증가할수록 SCOD/TCOD값이 증가하였다. 알칼리 가수분해가 산처리 보다는 슬러지 탄소원을 회수할 수 있는 더 적정한 처리방법이고, 알칼리의 전처리에 감마선 조사한 하수슬러지의 탄소원 회수율은 pH 13, 조사선량 20kGy에서 SCOB/TCOD 최대의 값인 59% 분석되었다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.11a
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• pp.312-313
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• 2015

무전해 도금은 석출응력이 낮고 작업하기가 용이하기 때문에 산업분야에 있어서 중요한 역할을 한다. 무전해 도금 공정에 있어서, 니켈금속은 차아인산염, 아미노보레인 혹은 수소화붕소 화합물($HBF_4$)에 의한 니켈이온의 화학적 환원에 의해 도금된다. 환원반응이 진행함에 따라서 도금액 중에서 니켈과 차아인산염 이온은 감소한다. 이에 이러한 이온을 보충하기 위하여 도금액 중에 황산니켈과 차아인산나트륨이 일반적으로 첨가된다. 하지만 축적된 인산염, 황산염, 나트륨과 이외의 물질이 전착 박막의 품질을 떨어뜨리고 도금액은 폐기되기도 한다. 니켈회수 속도는 종래의 50% 이하였던 것이 90%이상으로 향상되었다. 이온교환법은 니켈도금 폐액으로부터 니켈회수에 필요한 친환경적이고 원가절감의 기술이라고 사료된다. 특히, 갈탄이 저렴하고 양이온 교환성능이 뛰어나다. 이유는 -COOH, -OH 등의 기능성 그룹을 갖기 때문이다. Fe-P 화합물은 식물에 유용하지 못하고 마그네슘과 칼슘 기반의 석출물은 저렴하고 취급이 용이하며 비료와 같이 재활용이 가능하기 때문에 일반적인 인의 제거 수단이 될 수 있다. 본고에서는 니켈도금 폐액으로부터 인을 제거하는 데 $Ca(OH)_2$, $CaCl_2$와 $CaCO_3$를 채택하여 인이 제거되는 정도를 비교하였고 니켈회수율을 높이기 위하여 갈탄을 사용하였다.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.3
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• pp.261-267
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• 1999

Pot experiments were conducted to evaluate the phosphorus (P) availability with cropping in soils where P were highly accumulated. Bray 1-P contents of the used three soils were 584, 695 and $1043P\;mg\;kg^{-1}$, respectively. Corn ${\rightarrow}$ Chinese cabbage ${\rightarrow}$ Chinese cabbage ${\rightarrow}$ corn were sequentially grown from 1996 to 1998. P fertilizer was applied at three levels of 0 (P0), recommended application rate (P1), and double of recommended application rate (P2). At the end of each crop growth, available P content was determined by methods of Bray 1-P, Olsen-P and Lancaster-P. The growth of crops were not significantly affected by the rates of P applications. The relative yields of PO treatment were more than 88% of P1 treatment. The recoveries of added phosphorus were relatively low due to the high content of available phosphorus in soils. Although available phosphorus contents decreased through cropping, the concentration of soil available phosphorus was maintained high level even after the final cropping. In the case of P0 treatment in the three soils, the residual concentration was in the range of $410{\sim}610mg\;kg^{-1}$ for Bray 1-P, $284{\sim}410mg\;kg^{-1}$ for Olsen-P and $368{\sim}524mg\;kg^{-1}$ for Lancaster-P. The amount of soil available phosphorus decreased during the experiments was linearly regressed with high significance to the amount of P taken up by crops. The regressions of soil 1 as follow, Bray 1-P : y=149.7x=102.7, Lancaster-P : y=209.2x-140.2, Olsen-P: y=60.8x=19.9. The decrease rate of available phosphorus in the P0 treatment with cropping was described by an equation of first-order chemical reaction. The equation of soil1 was as follow: Bray 1-P: In(C)= -0.12N + 6.96 r=-0.991, Lancaster-P: In(C)= -0.14N = 6.88 r= -0.938, Olsen-P: In(C)= -0.07N = 6.37 r= -0.959. The rate constants seemed to be affected by ply, sand and silt content, and exchangeable $Ca^{2+}$ concentration. The times of cropping needed to reduce the content of available P to half of the initial or to the index level could be predicted by using that equation.