Biotechnological Reclamation of Oil-Polluted Soils

The aim of the paper was to determine the efficiency of petroleum hydrocarbons (PHs) degradation by developed bacterial consortium during bioremediation of oil-contaminated soils caused by accidental oil spills. The soil samples were collected from three different areas near the Bugruvate field of the Dnieper-Donets oil and gas region, Sumy region, Ukraine. The total petroleum hydrocarbon was determined by conducting measurements using a gravimetric method. Gas chromatographic analysis was performed for determination of polycyclic aromatic hydrocarbons. The level of oil contamination follows an increasing preferential order: Sample 1 < Sample 2 < Sample 3 (5, 10 and 15 g∙kg-1, respectively). The soil samples comprised different concentrations of PHs including n-alkanes, fluorine, anthracene, phenanthrene, pyrene, toluene, xylene, benzene and other PHs. The results of research indicated that the maximum oil degradation rate at the level of 80% was set at Cin within 4–8 g∙kg-1 and τ = 70 days, under natural condition. In order to improve the efficiency of bioremediation of oil-contaminated soils, bioaugmentation was performed using the developed preparation of such bacteria and fungi strains as Pseudoxanthomonas spadix, Pseudomonas aeruginosa, Rhodococcus opacus, Acinetobacter baumannii, Bacillus cereus, Actinomyces sp., Mycobacterium flavescens. The results showed 100% of oil concentration was assimilated after 20, 25 and 35 days for the soil samples with initial hydrocarbon concentrations at the level 5, 10 and 15 g∙kg-1, respectively. The bacterial consortium application (bioaugmentation) exhibited high efficiency compared to the indigenous microflora in the oil biodegradation. The optimal growth condition for the bacteria in this study can be set as follows: pH = 3–11, wide temperature range 0–35°C

Спосіб біоремедіації нафтозабруднених об'єктів

Спосіб біоремедіації нафтозабруднених об'єктів включає обробку нафтозабруднених ґрунтів буферним стабілізатором, сорбентом або розпушувачем та внесення препарату нафтоокиснювальних бактерій. Додатково після обробки ґрунту буферним стабілізатором вносять дигестат на рівні 20 т/га, а як буферний стабілізатор використовують фосфогіпс з розрахунку до 7 кг/т ґрунту, як сорбент або розпушувач використовують монтморилоніт або солому та компостовані відходи тваринництва і птахівництва з масовою часткою дози внесення 5-8 % незалежно від вибраної речовини. Препарат нафтоокиснювальних бактерій складається з таких штамів: Pseudoxanthomonas spadix BD-a59, Rhodococcus jostii RHA1, Rhodococcus aetherivorans IcdP1, Pseudomonas putida ND6, Pseudomonas stutzeri 19SMN4, Pseudomonas fluorescens UK4, Acinetobacter lactucae OTEC-02, Bacillus cereus F837/76.7.9 у кількості, що дорівнює титру 107-108 кл/мл. При цьому процес оброблення нафтозабруднених ґрунтів проходить за робочих температур 4-42 °C

Decontamination of oil-polluted soils: Power of electronic bioinformatic databases

The main idea was to solve the problem related to oil contamination of soil using bioremediation with bioaugmentation with modeled microorganism strains. The paper aimed to develop a bacterial consortium for petroleum hydrocarbon degradation during the biological treatment of oil-contaminated soils using electronic databases. The research methodology included an analysis of the mechanisms and metabolic pathways of petroleum hydrocarbon degradation and an assessment of the possible reaction modulus and enzymatic systems for the degradation of aromatic compounds. The taxonomic classification and review of oil compound transformation metabolic pathways were carried out using electronic KEGG, MetaCyc, and EzTaxon databases. The KEGG database was used to create a microbiological consortium of certain strains of bacteria that improved hydrocarbon degradation process performance. Identification of bacteria’s complete genome using Island Viewer 4 allowed to create of a consortium of oil-destructive bacteria consisting of such strains: Pseudoxanthomonas spadix BD-a59, Rhodococcus jostii RHA1, Rhodococcus aetherivorans IcdP1, Pseudomonas putida ND6, Pseudomonas stutzeri 19SMN4, Pseudomonas fluorescens UK4, Acinetobacter lactucae OTEC-02, Bacillus cereus F837/76.7.9. The ratio between the mentioned strains of microorganisms in the consortium was set at 20 % : 20 % : 15 % : 10 % : 10 % : 5 % : 5 % : 15 %. This bacterial consortium for aromatic hydrocarbons was created according to the metabolic information of basic enzymatic systems and the predominant transformation of particular oil compounds using the BacDive database

Digestate potential to substitute mineral fertilizers: Engineering approaches

The study aims to define the potential and technological aspects of the digestate treatment for its application as a biofertilizer. Life cycle assessment methodology was used in terms of digestate quality management. The potential of nutrients, organic carbon, and useful microelements in the digestate allows for its consideration as a mineral fertilizer substitute and soil improver. The valorization of digestate as fertilizer requires quality management and quality control. Based on the research focus, the successful soil application of digestate post-treatment technologies was analyzed. Among the different commercial options for digestate treatment and nutrient recovery, the most relevant are drying, struvite precipitation, stripping, evaporation, and membranes technology. Comparing the physical and chemical properties of the whole digestate, separated liquid, and solid liquor fractions showed that in the case of soil application of granular fertilizer, nutrients from the digestate are released more slowly than digestate application without granulation. However, realizing this potential in an economically feasible way requires improving the quality of digestate products through appropriate technologies and quality control of digestate products. To support the manufacture of quality digestate across Europe, the European Compost Network developed a concept for a panEuropean quality assurance scheme

Technologies for Environmental Safety Application of Digestate as Biofertilizer

The purpose of the paper is to determine the environmentally safe and economically feasible technology of biofertilizer production from the digestate including dewatering process. Methodological basis is based on the systematic approach to the determination of factors effected on the distribution of nutrients and pollutants between liquid and solid fractions after digestate separation. The paper analyzes modern technologies aimed at dewatering the digestate and reduction of its volume, showed their effectiveness. These technologies allow expanding the opportunities for commercialization of the digestate, increasing the cost of its transportation and application to the soil instead of complex fertilizers, using some valuable products. The results of the study showed that the ecological quality of the digestate is the highest as well as co-digested thermally pre-treated feedstock is used for solid-liquid separation in centrifuge with polymer addition as post-treatment approach to the flocculation. In order to increase efficiency of biofertilizer application the technological scheme of production process of granular fertilizers from digestate was proposed. Special feature of this scheme is in the use of phosphogypsum binder for the production of organo-mineral fertilizer that contributes phosphogypsum recycling in the waste management system