Field Test of In Situ Groundwater Treatment Applying Oxygen Diffusion and Bioaugmentation Methods in an Area with Sustained Total Petroleum Hydrocarbon (TPH) Contaminant Flow

Contamination of groundwater by petroleum hydrocarbons is a widespread environmental problem in many regions. Contamination of unsaturated and saturated zones could also pose a significant risk to human health. The main purpose of the study was to assess the efficiency of biodegradation of total petroleum hydrocarbon (TPH) in situ, in an area with loam and sandy loam soils, and to identify features and characteristics related to groundwater treatment in an area with a persistent flow of pollutants. We used methods of biostimulation (oxygen as stimulatory supplement) and bioaugmentation to improve water quality. Oxygen was added to the groundwater by diffusion through silicone tubing. The efficiency of groundwater treatment was determined by detailed monitoring. Implementation of the applied measure resulted in an average reduction in TPH concentration of 73.1% compared with the initial average concentration (4.33 mg/L), and in the local area, TPH content was reduced by 95.5%. The authors hope that this paper will contribute to a better understanding of the topic of groundwater treatment by in situ biodegradation of TPH. Further studies on this topic are particularly needed to provide more data and details on the efficiency of groundwater treatment under adverse geological conditions.

Pollution Level and Health Risk Assessment for the Total Petroleum Hydrocarbon in the Marine Environment, and Aquatic Products From the Southern Sea Area of Zhejiang Province, China

In order to evaluate the pollution level and risk of total petroleum hydrocarbon (TPH), seawater, sediments, and organisms were sampled from the southern sea area of Zhejiang province (Yangtze River Delta, China) between 2017 and 2019. Petroleum hydrocarbons were widely present in the aquatic environment as well as in products, and their concentrations were highly variable. The average value of PI exceeded 1 from 2017 to 2018, 45.46% to 69.19% samples for seawater and 56.87% to 50.00% samples for sediment were polluted. The results showed significant differences in the TPH concentration in various aquatic organism species. The average TPH value in aquatic organisms order was bivalve＞shrimp＞crab＞fish, further reflecting the ability to accumulate and metabolize TPH exists differently among aquatic organisms within the same culturing pond environment. It is relatively safe to eat aquatic products based on the exposure risk index far below threshold values in this study. Therefore, it will be prudent to undertake regular monitoring of TPH to ensure effective ecosystem functioning as well as seafood safety in Zhejiang southern ocean.

Efficacy of Amendments in TPH Removal during Bioremediation of Agricultural Crude Oil-polluted Soil

This study identified the efficacy of different amendments as biostimulants in bioremediation. This experiment was carried out for 4 weeks in the laboratory. One kilogram of pristine soil was spiked with one liter of crude oil in earthen pots, to each pot 10 grams of amendments were added and mixed thoroughly. The amendments used were poultry dropping (C-PD), cow dung (D-CD), N.P.K (E), and a control (A and B) setup undergoing natural attenuation. The microcosms’ initial physicochemical characteristics such as total organic nitrogen, pH, temperature, total organic carbon, total petroleum hydrocarbon (TPH), and polyaromatic hydrocarbon (PAH). The microbial enumeration was done for total heterotrophic bacteria (THB) and hydrocarbon utilizing bacteria (HUB). The molecular characterization of the pristine soil (A) and contaminated soil (B) was also done using the shotgun analysis. The THB of A and B was 1.3 x 107 and 2.1 x 102 while the HUB was 1.63 x 105 and 1.1 x 101on day 1 respectively. The THB of treatments during bioremediation at week 2 was 1.75 x 108, 1.89 x 108, 1.5 x 108 and 2.2 x 108 while at week 4, the THB was 1.90 x 108, 2.1 x 108, 2.20 x 108 and 2.25 x 108 while the HUB at week 2 was 1.20 x 105, 3.0 x 105, 2.5 x 105 and 1.98 x 105 while at week 4, the HUB was 2.0 x 106, 2.19 x 106, 2.46 x 106 and 2.1 x 106 for B, PD, CD ,and N.P.K respectively. The molecular characterization of A and B showed there was a higher microbial diversity in the contaminated soil than in the pristine soil. This study has shown that cow dung is more effective in the bioremediation of total petroleum hydrocarbon, and polyaromatic hydrocarbon in crude oil-contaminated soil.

BIODEGRADATION POTENTIAL OF RHIZOSPHERIC MICROORGANISMS OF RHIZOPHORA RACEMOSA IN CRUDE OIL CONTAMINATED MANGROVE SWAMP IN THE NIGER DELTA

Rhizophora racemosa (red mangrove tree) belongs to the family Rhizophoraceae; it is an important constituent of the mangrove swamp in Niger Delta, an oil producing region in Nigeria. The remediation of soils containing organic pollutants is possible with the use of microbial communities when the ecology is understood for potentials maximization. This study investigated the biodegradation potential of rhizospheric microorganisms of Rhizophora racemosa in crude oil- contaminated mangrove swamp in the Niger Delta.The total microbial count was determined by the serial dilution method. The hydrocarbon-utilizing bacteria and fungi were enumerated using Mineral Salts Agar containing crude oil as the sole carbon source. The biodegradation potential of these rhizomicrobes was determined using screen test, shake flask degradation tests, Total Organic Gas (TOG) and Total Petroleum Hydrocarbon (TPH) InfraCal Analyzer (HATR-T2 and CH). The turbidity, total organic gas (TOG-N) and total petroleum hydrocarbon were measured weekly for twenty-eight days. Hydrocarbon-degrading microbes isolated from the rhizosphere were identified as Marinococcus sp., Azotobacter sp., Acinetobacter sp. Aspergillus niger, Aspergillus flavus and Candida albicans. The highest rate of TPH reduction was recorded in Acinetobacter sp. (from 150 mg/L on day 1 to ˂0.0031 mg/L on day 14). This was followed by Candida albicans (148mg/L on day 1 to 2.68mg/L on day 28) and Aspergillus flavus (150mg/L on day 1 to 4.21mg/L on day 28) In conclusion, it can be inferred that the some rhizospheric microbes of Rhizophora racemosa can efficienctly degrade hydrocarbon up to 100% rate over a period of 28 days.

Phytoremediation of Crude Oil Polluted Microbial Augmented Soil Using Cyperus esculentus and Phyllanthus amarus

Aim: To assess the phytoremediation potential of Cyperus esculentus and Phyllanthus amarus in crude oil polluted soil and ascertain the enhancement of augmented microbes (fungi). Study Design: The study employs experimental design, statistical analysis of the data and interpretation. Place and Duration of Study: Rivers State University demonstration farmland in Nkpolu- Oroworukwo, Mile 3 Diobu area of Port Harcourt, was used for this study. The piece of land is situated at Longitude 4°48’18.50” N and Latitude 6ᵒ58’39.12” E measuring 5.4864 m x 5.1816 m with a total area of 28.4283 square meter. Phytoremediation process monitoring lasted for 240 days, analyses were carried out weekly at 30 days’ interval. Methodology: Seven (7) experimental plots (two Control (Unpolluted and polluted soil) and five polluted amended/treated plots) employing Randomized Block Design (each having dimensions: 100 x 50 x 30 cm LxBxH) were formed and mapped out on agricultural soil and left fallow for 6 days before contamination on the seventh day; after which it was allowed for 21 days for proper contamination and exposure to natural environmental factors (to mimic soil crude oil spill site); thereafter bioaugmenting organisms were applied. Baseline studies were carried out on the top soil before and after contamination, major parameters monitored and assessed were Total Petroleum Hydrocarbon (TPH) uptake by plant roots and stem, Polycyclic Aromatic Hydrocarbon (PAHs) and TPH reduction in soil. Other physicochemical analyzed in the soil of different plots were pH, Electrical Conductivity, Moisture Content, Total Nitrogen, Available Phosphorus, Potassium, Total Organic Carbon, Plant Height, Iron, Lead at regular intervals; days 1, 60, 90, 120, 150, 180, 210 & 240. Application of augmenting organisms was to enhance phytoremediation by test plant Cyperus esculentus (Cyp) and Phyllanthus amarus (Phy). The rate of phytoremediation was estimated from percentage (%) uptake of Total petroleum hydrocarbon (TPH) in plant roots and stem from day 1 -240; while percentage (%) reduction of TPH and PAHs in soil was estimated from day 1 to the residual at day 240. Results: The test plants decreased significant amount of crude oil as revealed in TPH uptake in their roots and Stem. Mean amount and percentage Total Petroleum Hydrocarbon (TPH) uptake by Cyperus esculentus roots and stem were; 152.33±50.34mg/kg, 12.57±4.16% and 201.13±8.80mg/kg, 13.27±0.58% respectively; while that of Phyllanthus amarus roots and stem were 141.50±35.62mg/kg, 11.68±2.94% and 174.44±19.98mg/kg, 11.51±1.32% respectively. Similar trend was observed in the control plots were TPH uptake by Cyperus esculentus roots and stem were; 24.2mg/kg, 2.00% and 20.01mg/kg, 1.32% respectively while in control plot of Phyllanthus amarus TPH uptake by roots and stem were 23.19mg/kg, 1.91% and 19.80mg/kg, 1.31% respectively. Comparatively, uptake of TPH was higher in plant stem than roots. From the initial TPH contamination value of 5503.00mg/kg , Total Petroleum Hydrocarbon Reduction and % Hydrocarbon Reduction in soil at 240 days in the different treatment plots in a decreasing order were as follows: PS+AN+MR+SMS+Phy (5470.9mg/kg; 99.43%) >PS+MR+SMS+Phy (5460.60mg/kg; 99.23%) >PS+AN+MR+Phy (5451.30mg/kg; 99.06%) >PS+MR+Cyp (5448.30mg/kg; 99.01%) >PS+AN+MR+Cyp (5440.00mg/kg; 98.86%) >PS+AN+Phy (5422.905mg/kg; 98.54%) >PS+Cyp (no amendment) (5380.90mg/kg; 97.78%). Comparative evaluation revealed higher reduction of PAHs in soil (plot) planted with Phyllanthus amarus. Highest PAHs reduction in soil was seen in PS+AN+MR+SMS+Phy (31.3mg/kg; 65.89%) while least was recorded in PS+ Cyp (no amendment) (23.4mg/kg, 49.26%). Conclusion: it was observed that plots planted with Cyperus esculentus (TPH 5492.75±76.36mg/kg) showed higher reduction of TPH from soil than those planted with Phyllanthus amarus (TPH 5449.72±18.27mg/kg); while PAHs degradation/reduction in plots planted with Phyllantus amarus (PAHs 28.72±2.74mg/kg; 60.46±5.77%) was higher than plots planted with Cyperus esculentus (PAHs 25.77±2.12mg/kg, 54.24±4.47%). More so, plots amended with augmentating microbes showed significant higher percentage reduction in hydrocarbon in the polluted soil than unamended polluted soil. It is therefore recommended that Cyperus esculentus is a suitable plant species for phytoremediation of crude oil contaminated soil with high TPH value while Phyllanthus amarus is the best option for phytoremediation of polluted soil with high PAHs value, in combination with augmenting microbes.

Physicochemical Indices of Phyto Remediated Hydrocarbon Polluted Soil and the Effect of Bio-nutrient Amendment

Aim: To assess the Physicochemical indices of Phytoremediated Crude Oil polluted amended soil using grass plant Cyperus esculentus (Cyp) and Phyllanthus amarus (Phy). Study Design: The study employs experimental design, statistical analysis of the data and interpretation. Place and Duration of Study: Rivers State University demonstration farmland in Nkpolu- Oroworukwo, Mile 3 Diobu area of Port Harcourt, was used for this study. The piece of land is situated at Longitude 4°48’18.50” N and Latitude 6ᵒ58’39.12” E measuring 5.4864 m x 5.1816 m with a total area of 28.4283 square meter. Phytoremediation process monitoring lasted for 240 days; analyses were carried out monthly at 30 days’ interval. Methodology: The study was carried out on Crude Oil Polluted soil (PS) amended with bio-nutrient supplements (Spent Mushroom Substrate (SMS) and selected fungi (Aspergillus niger(AN) andMucor racemosus (MR)) used to stimulate and augment the indigenous microbial population present in a crude oil polluted soil thereby enhancing hydrocarbon reduction in pari per sue with phytoremediation (uptake of Crude oil by test plants) over a period of 240 days. Ten (10) experimental plots (two Control (Unpolluted and polluted soil without amendment) and eight polluted amended/treated plots) employing Randomized Block Design (each having dimensions: 100 x 50 x 30 cm LxBxH); formed and mapped out on agricultural soil and left fallow for 6 days before contamination on the seventh day; after which it was allowed for 21 days for proper contamination and exposure to natural environmental factors (to mimic soil crude oil spill site); thereafter nutrients/organics (biostimulating agents) and bioaugmenting organisms were applied. Baseline studies were carried out on soil profile before and after contamination, major parameters monitored and assayed were Total Petroleum Hydrocarbon (TPH) uptake by plant roots and stem, Polycyclic Aromatic Hydrocarbons (PAHs) and TPH reduction in soil. Other physicochemical properties analyzed in the soil from different plots were pH, Electrical Conductivity, Moisture Content, Total Nitrogen, Available Phosphorus, Potassium, Total Organic Carbon, Plant Height, Iron, Lead and Zinc at regular intervals; days 1, 60, 90, 120, 150, 180, 210 & 240. The rate of phytoremediation was estimated from percentage (%) uptake of Total petroleum hydrocarbon (TPH) in plant roots and stem from day 1 -240; while percentage (%) reduction of TPH and PAHs in soil was estimated from day 1 to the residual at day 240. Results: The test plants decreased significant amount of crude oil as revealed in TPH uptake in their roots and Stem. Mean amount and percentage Total Petroleum Hydrocarbon (TPH) uptake by Cyperus esculentus roots and stem were; 152.33±50.34mg/kg, 12.57±4.16% and 201.13±8.80mg/kg, 13.27±0.58% respectively; while that of Phyllanthus amarusroots and stem were 141.50±35.62mg/kg, 11.68±2.94% and 174.44±19.98mg/kg, 11.51±1.32% respectively; revealing higher Uptake of TPH in plant stem than roots. From the initial TPH contamination value of 5503.00mg/kg, it was observed that plots planted with Cyperus esculentus (TPH 5492.75±76.36mg/kg) showed higher reduction of TPH from soil than those planted with Phyllanthus amarus(TPH 5449.72±18.27mg/kg); while PAHs degradation/reduction showed a reverse trend with plots planted with Phyllanthus amarus (PAHs 28.72±2.74mg/kg; 60.46±5.77%) higher than plots planted with Cyperus esculentus s (PAHs 25.77±2.12mg/kg, 54.24±4.47%). Conclusion: Plots planted with Cyperus esculentus showed higher reduction of TPH from soil than those planted with Phyllanthus amarus while PAHs degradation/reduction in plots planted with Phyllanthus amarus was higher than plots planted with Cyperus esculentus. TPH uptake was higher in plant stems than roots; more so, plots amended with nutrient supplements showed significant higher percentage reduction in hydrocarbon in the polluted soil than unamended polluted soil. It is therefore recommended that Cyperus esculentus is a suitable plant species for phytoremediation of crude oil contaminated soil with high TPH value while Phyllanthus amarusis the best option in phytoremediation of polluted soil with high PAHs value, both in combination with bio-nutrient supplement.

Electro-Kinetic Degradation of Diesel Originated from a Costal Crude Oil Terminal

: The present study evaluated the effect of the integration of electro-kinetic (EK) oxidation with sonication degradation of diesel in a hydrocarbon contaminated wastewater. The effect of operational parameters including initial pH (3 - 9), sonication (100 - 300 W), voltage (0.5 - 3 V/cm), and reaction time (60 - 150 min) were studied consecutively. The highest total petroleum hydrocarbon (TPH) destruction rate of 40% was achieved at pH 5. Also, increasing the sonication intensity up to 300 W improved the removal rate to 70%. The pseudo-first-order kinetic model was selected due to higher correlation coefficient. Considering the obtained integration of EK oxidation with sonication is a viable and efficient technology for treatment of diesel contaminated wastewaters.