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Aim: Microbial air quality over illegal refuse dump sites in Port Harcourt, Nigeria, was conducted to assess the aero-microbial contaminant of dumpsite to the closest neighbourhood and the harmful distance. Place and Duration of Study: The dump sites were located at oil mill market (Latitude 4.8578 N4°51'28.06344'' Longitude 7.06653 E7°3'59.50152'') and Iloabuchi Timber market (longitude N4.790191, latitude E6.988416) all in Port Harcourt, South South Nigeria. The samplings were carried out between June (dry season) and July (wet season) 2018. Methodology: The microbial concentration of air around the dump sites were measured using the “sedimentation method” that involved exposing different sterile Petri dishes containing nutrient agar, Mac Conkey agar, and sabauroud dextrose agar to the air for ten minutes. The exposures were carried out at different locations within and around the dump site viz; Top of the dumpsite at different altitude (3ft, 6ft and 9ft above dump surface), 0m, 10m away from the dumpsite, and at the nearest neighbourhood which is about 100m away from the dumpsite. These samplings were carried out to the left and right sides of the dump sites. The samplings were carried out between June and July 2018, so as to compare the microbial load between the dry and wet seasons. Result: The microbes at the dump sites were in most cases higher than the microbes at the neighbourhood (100m away to the left and right). Seasonal occurrence revealed that microbial load in air during the dry season (6.037±0.92 cfu/min-m2) is higher than during the wet season (1.814±0.19 CFU/min-m2). Percentage variation amongst heterotrophic bacterial isolates revealed, Staphylococcus massiliensis (47.90%) > Erwinia psidii (18.24%) > Shigella dysenteriae (18.17%) > Bacillus simplex (6.08%) > Saminicoccus kunminingensis (3.23%) > Corynebacteriun afermentans (3.00%) > Paenibacillus celluositrophycus (2.25%) > Streptococcus parasuis (5.26%); percentage variation amongst enteric bacterial isolates revealed, Staphylococcus aureus (28.57%) > Geobacillus stearothermophilus (20.82%) > Escherichia coli (8.16%) and Bacillus carboniphilus (8.16) > Salmonella enterica (6.94%) > Bacillus smithii (6.12%) > Macrococcus brunensis (4.49%) > Lactobacillus kitasatonis (3.67%) > Klebsiella pneumonia (2.86%) > Staphylococcus saccharolyticus (2.45%) > Bacillus badius (2.04%) = Paenibacillus lautus (2.04%) > Brevibacillus laterosporus (1.63%). The fungal distribution revealed, Aspergillus fumigatus (16.62%) > Microsporium canis (15.40%) > Aspergillus flavus (14.75%) > Aspergillus niger (10.99%) > Conidiobolus coronatus (10.19%) > Pheaocremonium parasiticum (6.97%) > Fusarium chlamydosporium (6.70%) > Trychophyton etriotrephon (5.63%) > Trychophyton quinckeanum (4.02%) > Lichtheeimia corymbifera (3.57%) > Cladosporium cladosporioides (2.95%) > Saccharomyces spp (2.68]%). Conclusion: The presence of microbial pathogens such as Escherichia coli, Staphylococcus aureus, Bacillus spp, Klebsiella pneumonia, Salmonella enterica and Aspergillus species, is alarming and of great health concern. The harmful distance exceeds 100m away from the dump site which encroached 30 meters into residential areas. This research work revealed the relevance of Environmental air monitoring in any Governmental Waste Management System and the potential hazard of open dump system of waste disposal around residential area.

Aim: To assess the Mycoremediation potential of Mucor racemosus and Aspergillus niger in open field crude oil contaminated soils in Rivers State, Nigeria.  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. Mycoremediation process monitoring lasted for 56 days, analyses were carried out weekly at 7 days’ interval. Methodology: Five (5) experimental plots were employed using a Randomized Block Design each having dimensions of 100 x 50 x 30 cm (Length x Breadth x Height) and were formed and mapped out on agricultural soil, each plot was contaminated with 22122.25g of Crude Oil except Control 1 and left fallow for 6 days after contamination for proper contamination and exposure to natural environmental factors to mimic crude oil spill site. On the seventh day bio-augmentation process commenced using two (2) fungal isolates namely Aspergillus niger [Asp] and Mucor rasemosus [Muc]). Two (2) control plots (P1: Uncontaminated and unamended soil - CTRL 1 US) and P2: Crude Oil contaminated but unamended soil - CTRL 2 CS); P3 = P5 were contaminated and amended/bioaugmented (P3: CS+Asp, P4: CS+Muc, P5: CS+Asp+Muc respectively. Soil profile before and after contamination was assayed while parameters like Temperature, pH, Nitrogen, Phosphorus, Potassium and Total Petroleum Hydrocarbon (TPH) contents were monitored throughout the experimental period. Microbial analyses such as Total Heterotrophic Bacteria (THB), Total Heterotrophic Fungi (THF), Hydrocarbon Utilizing Bacteria (HUB) and Hydrocarbon Utilizing Fungi (HUF) were recorded. Bioremediation efficiency was estimated from percentage (%) reduction of Total Petroleum Hydrocarbon (TPH) from day 1 to the residual hydrocarbon at day 56 of bio- augmentation/ biostimulation plots with the control. Results: Results revealed actual amount of remediated hydrocarbon and % Bioremediation Efficiency at 56 days in the different treatment plots (initial TPH contamination value of 8729.00mg/kg) in a decreasing order as follows: CS+Muc (8599.19mg/kg; 33.66%) > CS+Asp+Muc (8357.31mg/kg; 33.04%) > CS+Asp (8341.58mg/kg; 32.98%) > CTRL 2 -CS (Polluted soil without amendment) (81.06mg/kg; 0.32%). Microbiological results After fifty-six (56) days of bioremediation monitoring; %HUB were as follows; CS+Asp+Muc (45.30%) > CS+Asp (40.32%) > CS+Muc (35.01%) > CTRL 2 –CS (30.43%) > CTRL 1 – US (0%). These results indicate that the presence of the contaminated crude oil stimulated and sustained the growth of Hydrocarbon Utilizing Bacteria (HUB) in the contaminated plots (P2 - P3); more so, the higher growth in the enhanced bio-augmented plots (P3 – P5) shows the positive impact of fungal bio-augmentation in bioremediation of crude oil polluted soil. It was further observed that treatment plots with higher HUB or HUF had higher percentage (%) bioremediation efficiency; that is, the higher the sustained HUB and HUF population, the higher the %Bioremediation process. Hydrocarbon Utilizing Bacteria (Log10 CFU/g): CS+Asp (4.20) (Day 35) > CS+Muc+Asp (4.18) (Day 35) > CS+Muc (4.08) (Day 28) > CTRL 2 – CS (3.95) (Day 21) > CTRL 1 – US (3.78) (Day 35). (Fig. 3). Hydrocarbon Utilizing Fungi (Log10 CFU/g): CS+Asp (4.68) (Day 35) > CS+Muc+Asp (4.58) (Day 35) > CS+Muc (4.48) (Day 35) > CTRL 2 – CS (4.23) (Day 21) > CTRL 1 – US (2.85) (Day 42). Conclusion: Study showed that bioremediation of crude oil-contaminated soils with Bioaugmenting fungus singly may be more effective than combination with others depending on the type of substrate used, nature of the hydrocarbon utilizing organism and environmental conditions prevalent as seen in Mucor racemosus having higher bioremediation potential than when combined with Aspergillus niger. Notably, Hydrocarbon Utlilizing Bacteria (HUB) and Hydrocarbon Utilizing Fungi (HUF) which are the key players in Bioremediation has its peak count value on Day 35, this confers that nutrient renewal on bioremediation site should be at interval of 35 days for continuous effective bioremediation of hydrocarbon pollutants. It is therefore recommended that single microbes of high bioremediation potential could be used since its more effective than consortium of many hydrocarbon utilizing microbes. Also, nutrient or bio-augmenting microbes’ renewal on bioremediation site should be at an interval of 35 days for continuous effective bioremediation of hydrocarbon pollutants.

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