The reuse of treated sewage for irrigation is considered as an important alternative water source in the new water management strategy of the countries that face a severe deficiency of water resources such as the Middle East countries. The organic material and fertilizing elements contained in biosolids are essential for maintaining soil fertility. However, both treated sewage and biosolids contain a large diversity of pathogens that would be transmitted to the environment and infect human directly or indirectly. Therefore, those pathogens should be reduced from the treated sewage and biosolids before the reuse in the agriculture. This paper reviews the considerations for reuse of treated sewage and biosolids in agriculture and further treatments used for reduction of pathogenic bacteria. The treatment methods used for the reduction of pathogens in these wastes have reviewed. It appeared that the main concern associated with the reduction of pathogenic bacteria lies in their ability to regrow in the treated sewage and biosolids. Therefore, the effective treatment method is that it has the potential to destruct pathogens cells and remove the nutrients to prevent the regrowth or recontamination from the surrounded environment. The removal of nutrients might be applicable in the sewage but not in the biosolids due to high nutrient contents. However, the reduction of health risk in the biosolids might be carried out by regulating the biosolid utilization and selecting the plant species grown in the fertilized soil with biosolids.

Introduction Palm oil mill effluent (POME) contains large quantities of organic matter in the form of total suspended solids (TSS), volatile suspended solids (VSS), total solids (TS), oil and grease (O & G) that increase biochemical oxygen demand (BOD) and chemical oxygen demand (COD) of POME if left untreated. The main aim of the present study was to investigate the ability of bacterial strains either pure (individually) or mixed (combinations), to degrade and metabolize organic load from palm oil mill effluent. Results Sequencing of the 16S rRNA of the isolates suggests that they were identified as Micrococcus luteus 101 PB, Stenotrophomonas maltophilia 102 PB, Bacillus cereus 103 PB, Providencia vermicola 104 PB, Klebsiella pneumoniae 105 PB and Bacillus subtilis 106 PB. The use of mixed cultures in the present study showed more extensive removal of organic load (COD and BOD) than pure single cultures. Mixed cultures were found to reduce the pollutant dynamically. Thus, the mixed cultures C 1 (Bacillus cereus 103 PB and Bacillus subtilis 106 PB) were the most effective bacterial combination for use in biological treatment technology of POME having the highest COD and BOD reduction rate. C 1 produced the highest degradative activity in reducing COD (90.64 %) and BOD (93.11 %). Conclusion The indigenous microbial isolates from POME were observed to possess potential to degrade organic components whereas the use of mixed cultures resulted in more extensive degradation of COD and BOD than pure single cultures. This suggests that mixed culture of bacteria in the present study can be used for bioremediation of environment contaminated with polluted wastewaters. This study, however, indicates the prospect of isolating indigenous microorganisms in the POME for effective biotreatment of POME.

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Contamination by petroleum products is a common occurrence in various depots in Nigeria. Suleja depot in recent times has recorded several petroleum spillages and fire incidence attributed to petroleum products storage and distribution. This study was aimed at determining the microbiological quality of soil and water sources in communities around petroleum products depot in Suleja, Nigeria. Soil and water samples were collected from petroleum depot and the five communities around the petroleum products depot and a control site. Microorganisms in the soil and water samples were enumerated by spread inoculation on general purpose media and selective media. Bacterial and fungal isolates were tested for their potential to utilize petroleum products in a Bushnell Haas Broth containing 0.05 mL of petroleum products (diesel, kerosene, engine oil, crude oil) as a source of carbon and energy. The utilization rate was determined by spectrophotometry. The capacities of selected bacterial and fungal isolates to mineralize crude oil were further tested in minimal salt medium. The bacteria isolated were Staphylococcus aureus, Streptococcus faecalis, Proteus mirabilis, Pseudomonas aeruginosa, Bacillus subtilis and Escherichia coli. The microbial isolates were not evenly distributed in the six experimental and control plots. Soil samples had higher aerobic heterotrophic bacterial counts than the water samples. Crude oil was most utilized by the microbial isolates. Bacterial isolates from genera Pseudomonas and Bacillus had the highest capacity in utilizing the petroleum products. Among the fungal species, Aspergillus niger and Penicillium notatum exhibited greater capacity to utilize the petroleum products. Present study revealed isolates capable of utilizing the various petroleum products which can be useful in oil spill bioremediation in the tropical environments.

This study was aimed at identifying indigenous microorganisms from palm oil mill effluent (POME) and to ascertain the microbial load. Isolation and identification of indigenous microorganisms was subjected to standard microbiological methods and sequencing of the 16S rRNA and 18S rRNA genes. Sequencing of the 16S rRNA and 18S rRNA genes for the microbial strains signifies that they were known as Micrococcus luteus 101PB, Stenotrophomonas maltophilia 102PB, Bacillus cereus 103PB, Providencia vermicola 104PB, Klebsiella pneumoniae 105PB, Bacillus subtilis 106PB, Aspergillus fumigatus 107PF, Aspergillus nomius 108PF, Aspergillus niger 109PF and Meyerozyma guilliermondii 110PF. Results revealed that the population of total heterotrophic bacteria (THB) ranged from 9.5 × 105 – 7.9 × 106 cfu/mL. The total heterotrophic fungi (THF) ranged from 2.1 × 104 – 6.4 × 104 cfu/mL. Total viable heterotrophic indigenous microbial population on CMC agar ranged from 8.2 × 105 – 9.1 × 106 cfu/mL and 1.4 × 103 – 3.4 × 103 cfu/mL for bacteria and fungi respectively. The microbial population of oil degrading bacteria (ODB) ranged from 6.4 × 105 – 4.8 × 106 cfu/mL and the oil degrading fungi (ODF) ranged from 2.8 × 103 – 4.7 × 104 cfu/mL. The findings revealed that microorganisms flourish well in POME. Therefore, this denotes that isolating native microorganisms from POME is imperative for effectual bioremediation, biotreatment and biodegradation of industrial wastewaters.