A Remediation Study of Contaminated Marine Sediment through Application of Naturally Developed Oxygen Releasing Compound

Md Akhte Khirul,김범근,조대철,권성현 한국폐기물자원순환학회 2020 한국폐기물자원순환학회지 Vol.37 No.1

Blocking the influx of nutrients from contaminated sediment and reducing terrigenous loads are essential to controleutrophication in coastal water areas. In this study, the use of an oyster-shell-based ORC (oxygen-releasing compound) wasinvestigated with respect to nutrients such as nitrogen, phosphorous, and sulfur compounds in the sediment environment. The ORC, which was produced by pyrolyzing oyster shell powder, was found to be overoxidized and consisted of calciumperoxide. A series of experiments simulating a typical overlying water-sediment system were carried out in open-lidcylindrical columns over the fifteen-day experimental period. The elution and distribution of crucial contaminating specieswithin that system are discussed. T-N, NH4+-N, T-P, and Pi propagated with time toward the overlying water from thesediment through diffusive migration, showing a constrained increase over distance at the sediment-water interface. Thenitrate levels decreased with time, possibly due to local denitrification. Partial oxidation in a homogenized mixture ofsediment and oxidized oyster shell powder resulted in an increased DO level within the experimental time frame, whichin turn caused T-N, NH4+-N, T-P, and Pi to propagate at a lower rate than sediment without any ORC. Analyses for sulfatesand sulfides in the sediment mixed with ORC confirmed that the chemical environment changed into a more oxidized statein fifteen days. Diffusive migration, along with chemical reactions and/or adsorption, successfully explained the propagationand distribution of the concerned nutrient species resulting from the use of oyster shell powders.

Distribution of Vital, Environmental Components and Nutrients Migration Over Sedimentary Water Layers

Khirul, Md Akhte,Kim, Beom-Geun,Cho, Daechul,Kwon, Sung-Hyun The Korean Environmental Sciences Society 2021 한국환경과학회지 Vol.30 No.3

Contaminated marine sediment is a secondary pollution source in the coastal areas, which can result in increased nutrients concentrations in the overlying water. We analyzed the nutrients release characteristics into overlying water from sediments and the interaction among benthic circulation of nitrogen, phosphorus, iron, and sulfur were investigated in a preset sediment/water column. Profiles of pH, ORP, sulfur, iron, nitrogen, phosphorus pools were determined in the sediment and three different layers of overlying water. Variety types of sulfur in the sediments plays a significant role on nutrients transfer into overlying water. Dissimilatory nitrate reduction and various sulfur species interaction are predominantly embodied by the enhancing effects of sulfide on nitrogen reduction. Contaminant sediment take on high organic matter, which is decomposed by bacteria, as a result promote bacterial sulfate reduction and generate sulfide in the sediment. The sulfur and iron interactions had also influence on phosphorus cycling and released from sediment into overlying water may ensue over the dissolution of ferric iron intercede by iron-reducing bacteria. The nutrients release rate was calculated followed by release rate equation. The results showed that the sediments released large-scale quantity of ammonium nitrogen and phosphate, which are main inner source of overlying water pollution. A mechanical migration of key nutrients such as ammonia and inorganic phosphate was depicted numerically with Fick's diffusion law, which showed a fair agreement to most of the experimental data.

Behaviors of nitrogen, iron and sulfur compounds in contaminated marine sediment

Md Akhte Khirul,Daechul Cho,Sung-Hyun Kwon 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.3

The marine sediment sustains from the anoxic condition due to increased nutrients of external sources. The nutrients are liberated from the sediment, which acts as an internal source. In hypoxic environments, anaerobic respiration results in the formation of several reduced matters, such as N₂ and NH₄<SUP>+</SUP>, N₂O, Fe<SUP>2+</SUP>, H₂S, etc. The experimental results have shown that nitrogen and sulfur played an influential, notable role in this biogeochemical cycle with expected chemical reductions and a ‘diffusive’ release of present nutrient components trapped in pore water inside sediment toward the bulk water. Nitate/ammonium, sulfate/sulfides, and ferrous/ferric irons are found to be the key players in these sediment-waters mutual interactions. Organonitrogen and nitrate in the sediment were likely to be converted to a form of ammonium. Reductive nitrogen is called dissimilatory nitrate reduction to ammonium and denitrification. The steady accumulation in the sediment and surplus increases in the overlying waters of ammonium strongly support this hypothesis as well as a diffusive action of the involved chemical species. Sulfate would serve as an essential electron acceptor so as to form acid volatile sulfides in present of Fe<SUP>3+</SUP>, which ended up as the Fe<SUP>2+</SUP> positively with an aid of the residential microbial community.

Submission of “Electric power generation from sediment microbial fuel cells with graphite rod array anode”

Md Akhte Khirul,Zejie Wang,Bongsu Lim 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.2

Sediment microbial fuel cells (SMFCs) illustrated great potential for powering environmental sensors and bioremediation of sediments. In the present study, array anodes for SMFCs were fabricated with graphite rods as anode material and stainless steel plate as electric current collector to make it inconvenient to in situ settle down and not feasible for large-scale application. The results demonstrated that maximum power of 89.4 μW was obtained from three graphite rods, twice of 43.3 μW for two graphite rods. Electrochemical impedance spectroscopy revealed that three graphite rods resulted in anodic resistance of 61.2 Ω, relative to 76.0 Ω of two graphite rods. It was probably caused by the parallel connection of the graphite rods, as well as more biomass which could reduce the charge transfer resistance of the biofilm anode. The presently designed array configuration possesses the advantages of easy to enlarge the surface area, decrease in anodic resistance because of the parallel connection of each graphite rod, and convenience to berry into sediment by gravity. Therefore, the as prepared array node would be an effective method to fabricate large-scale SMFC and make it easy to in situ applicate in natural sediments.

Evaluating Remediation Efficiency of Functional Oyster Shell Powder for Organically Enriched Sediment

Md Akhte Khirul,김범근,조대철,권성현 한국폐기물자원순환학회 2020 한국폐기물자원순환학회지 Vol.37 No.5

Eutrophication is a serious environmental issue in coastal areas, caused by increased nutrient concentration from externalsources. Nutrients could augment in the bottom sediment and be released into overlying water, acting as an internal nutrientsource. Converted oyster shell powders were used to evaluate the suppression of nutrients release from bottom sediments. Two kinds of oyster shell powder were applied into the sediment in the individual column with the control column. Thenatural oyster shell powder (NOSP) was composed of calcium carbonate and the functional oyster shell powder (FOSP)was composed of calcium peroxide. In the column where FOSP was applied, pH was increased due to hydrolysis of calciumperoxide in the overlying water. The concentration of dissolved oxygen in the FOSP-treated columns was higher than thatof the control column. The FOSP could suppress the release of ammonia nitrogen and phosphates from the sediment intothe overlying water. It was proven that FOSP can effectively adsorb phosphates from organically enriched sediments. Overall, the application of FOSP could effectively control nutrient release from the sediment to overlying water and helpreduce the eutrophication in the coastal areas. 없음

Effect of oyster shell powder on nitrogen releases from contaminated marine sediment

Md Akhte Khirul,Beom-Geun Kim,Daechul Cho,Gilsun Yoo,Sung-Hyun Kwon 대한환경공학회 2020 Environmental Engineering Research Vol.25 No.2

Nitrogen flux release from organically enriched sediments into overlying water, which may have significantly influence on water quality and increasing continuous eutrophication. The purpose of this study is to evaluate the remediation efficiency of oyster shell powder and its treated product into organically enriched sediment in terms of nitrogen flux, organic matter, chlorophyll-a, pH and dissolved oxygen (DO). The TOSP was mainly composed of CaO2. The application of TOSP into the sediment has increased the pH, DO and significantly decreased the concentrations of NH₄+-N and T-N compared to other basins. On the other hand, nitrate was enriched with the addition of treated oyster powder, an oxygen releasing compound on both phases. Furthermore, chlorophyll-a was found to be increasing with time in the control basin meanwhile it dropped drastically with the addition of TOSP, which implied on the repression of algal growth owing to blockage of nitrogen source migrating from the sediment. This study has shown that the TOSP was effective to improve sediment-water quality, diminish eutrophication and control harmful algae blooms in a marine environment. Therefore, it is a good reference as an effective environmental remediation agent.

Prevent the Nutrients Release from Polluted Marine Sediments Using Recycled Waste Oyster Shell Powder

Md Akhte Khirul,김범근,조대철,권성현 한국환경과학회 2021 한국환경과학회지 Vol.30 No.4

To evaluate the remediation performance of recycled oyster shell powders to control nutrients release from polluted sediments. Different types of recycled oyster shell powder were applied on separated bottom sediments. The first type of oyster shell powder is Calcined Oyster Shell Powder (COSP) and another consist of ultrasonicated oyster shell powder (SOSP) which were composed of calcium peroxide. The recycled oyster shell powders were improving the water quality as slow oxygen releasing compound. The experimental results indicated that the Dissolved Oxygen (DO) in the treated columns were higher than the control column. pH was increased in the both experimental columns due to the hydrolysis of CaO2. Meanwhile, recycled oyster shell powders could prevent the nutrients (nitrogen and phosphorus) release from sediments into the overlying water. In addition, the total nitrogen and total phosphorus concentrations of the COSP applied column were decreased 27% and 20% compared to the control column respectively and the SOSP applied column were decreased 33% and 27% compared to control in the overlying water. It was proved that, COSP and SOSP can effectively adsorb phosphorus from sediments and prevent phosphorus release into overlying water from bottom sediments. In conclusion, COSP and SOSP applications was increased DO in the overlying water and nutrient released controlled effectively from the sediment.

The effect of calcium peroxide originating from oyster shell powder on control of phosphorus compounds in oceanic sediment

김범근,Md Akhte Khirul,조대철,권성현 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.1

This study evaluated the water quality above the marine sediment by inputting oxygen releasing compound (ORC) processed from calcined oyster shells. Presumed vital parameters such as DO, pH, ORP, chlorophyll-a and classified phosphorous compounds were monitored for 20 d. ORP decreased with time in the control bed, while it increased to a positive value as a result of the ORC effect. DO kept showing a relatively high concentration in ORC treated column. We observed an increase of chlorophyll-a and a decrease of dissolved inorganic phosphate (DIP) simultaneously, which meant the released inorganic phosphorus would convert to an organic form in the overlying water. TP rises were the lowest in the ORC column (79%), meanwhile in the control column those went up to 0.304mg/L (85%). Also, phosphorus fractions were measured in the sediment: Fe-P decreased in control while Fe-P and Ca-P soared greatly in the ORC column. This implies that in more oxidized environment inorganic phosphate bound to Ca-species would be eliminated as solidified precipitates in the sediment pore water, and it consequently suppressed the release of phosphates to the overlying water. The results indicate that the release of phosphorus and resulting eutrophication could be effectively controlled via the local environment improved by calcined ORC.

Changes in Phosphorus and Sediment Oxygen Demand in Coastal Sediments Promoted by Functionalized Oyster Shell Powder as an Oxygen Release Compound

( Beom-geun Kim ),( Md Akhte Khirul ),( Dae-chul Cho ),( Sung-hyun Kwon ) 한국환경과학회 2019 한국환경과학회지 Vol.28 No.10

In this study, we performed a sediment elution experiment to evaluate water quality in terms of phosphorus, as influenced by the dissolved oxygen consumed by sediments. Three separate model column treatments, namely, raw, calcined, and sonicated oyster shell powders, were used in this experiment. Essential phosphorus fractions were examined to verify their roles in nutrient release from sediment based on correlation analyses. When treated with calcined or sonicated oyster shell powder, the sediment-water interface became “less anaerobic,” thereby producing conditions conducive to partial oxidation and activities of aerobic bacteria. Sediment Oxygen Demand (SOD) was found to be closely correlated with the growth of algae, which confirmed an intermittent input of organic biomass at the sediment surface. SOD was positively correlated with exchangeable and loosely adsorbed phosphorus and organic phosphorus, owing to the accumulation of unbound algal biomass-derived phosphates in sediment, whereas it was negatively correlated with ferric iron-bound phosphorus or calcium fluorapatite-bound phosphorus, which were present in the form of "insoluble" complexes, thereby facilitating the free migration of sulfate-reducing bacteria or limiting the release from complexes, depending on applied local conditions. PCR-denaturing gradient gel electrophoresis revealed that iron-reducing bacteria were the dominant species in control and non-calcined oyster shell columns, whereas certain sulfur-oxidizing bacteria were identified in the column treated with calcined oyster powder.

CaO₂ 적용에 따른 퇴적물의 P fraction 변화와 수질에 미치는 영향

김범근 ( Beom-geun Kim ),모하메드아케트키룰 ( Md Akhte Khirul ),권성현 ( Sung-hyun Kwon ) 한국환경과학회 2019 한국환경과학회지 Vol.28 No.5

This study was investigated to improve the phosphorus release and water quality by transformation of sedimentary P fraction for application of CaO₂. For the experiment, 0.5% (w/w) of CaO₂ was homogenized in the sediment and incubated with the control for 20 days. The analytical results showed that pH increased with CaO₂ and redox potential (ORP) was improved in the sediment of the reactor. The growth rate of chlorophyll-a was lower in the CaO₂ reactor and Dissolved Oxygen (DO) of overlying water maintained higher than that of the control. Total phosphorus (T-P) concentration in the overlying water increased from the initial concentration to 0.304mg/L in the control at 20 days. The reactor of CaO₂ was lowered by 29.3%. Ex-P, Fe-P and Ca-P in sediment P fraction were increased with the CaO₂. The formation of bound Fe-P and Ca-P in the sediments seemed to control the release of P by removing the Soluble Reactive Phosphorus (SRP) presented in the pore water. From the result, this indicated that the reduction of P release from the sediments seems to be effective in suppressing the eutrophication of P and improving the oxygen condition in the water quality with the application of CaO₂.