Microbial Diversity of Nigerian Sludge and Its Potential for Use as Biofertilizer

Sludge samples were collected from a wastewater treatment plant in Nigeria for characterization and evaluation for agricultural applications. Conventional and Molecular techniques were adopted for the isolation and identification of indigenous microorganisms and resulting isolates were characterized and identified by consulting Bergey’s manual of determinative bacteriology and subjected to further screenings to assess their biofertilizer potential using standard microbiological techniques. The viable cells obtained were enumerated and were found to be in the range of 1.03 ± 0.09 x103 cfu/g to 7.45 ± 0.78 x103 cfu/g for heterotrophic Bacteria and 1.63 ± 0.74 x103 cfu/g for fungal community. The Molecular analysis carried out revealed a rich assemblage of diverse species of microorganisms with Bacteria (99.40%) being the most dominant group, followed by Fungi (0.39%) and others (0.21%). Thirty (30) isolates belonging to four (4) Phyla was recovered culturally and identified with Firmicutes 9(30%) being the most dominant group, followed by Proteobacteria 8(26.7%) and Zygomycota 1(3.33%) was the least dominant. The phosphate solubilization index range from 0.86 to 6.3 for bacterial and 2.5 to 3.8 for fungal isolates respectively. The molecular analysis also revealed microbes adept at improving soil fertility to include those in the order Rhizobiales and Actinomycetales. Although pathogens are of a concern in the land application of sludge, our findings have revealed rich microbial consortia of heterotrophic microorganisms whose beneficial attributes can be harnessed to produce nutrient rich biofertilizer and soil amendment.</jats:p

Anaerobic co-digestion of spent coconut copra with cow urine for enhanced biogas production

Laboratory-scale bioreactors were used to co-digest spent coconut copra (SCC) and cow urine (CU) as a co-substrate (SCC + CU) in a batch mode under thermophilic condition (45 ± 2°C) in order to enhance biogas production. The effect of CU pretreatment on the performance indicators (biogas and biomethane yields, total solids (TS), and volatile solids (VS) reduction, pH and volatile fatty acids (VFAs) concentrations) were also examined. This was compared with mono-digestion of SCC. The experiment was performed with different mixing ratios in reactors labelled as follows: A = 75 g SCC + 5 ml CU; B = 70 g SCC + 10 ml CU; C = 65 g SCC + 15 ml CU; and D (control) = 80 g SCC at a hydraulic retention time of 42 days. Co-digestion (SCC + CU) significantly improved anaerobic digestion (AD) performance resulting in a threefold and fivefold increase in biogas and biomethane production, respectively, with concomitant TS (44.9–57.7%) and VS (55.4–60.3%) removal efficiencies. But for mono-digestion (control experiment), all CU treated and co-digestion assays showed pH stability ranging between 6.6 and 7.4 and VFAs’ concentrations ranging from 15–330 mgL-1. By acting as a buffer, CU effectively enhanced the AD performance of SCC as demonstrated in this study. </jats:p

Enhanced Biogas and Biofertilizer Production from Anaerobic Codigestion of Harvest Residues and Goat Manure

Comparative assays were conducted to assess the biogas and biofertilizer production efficiency from anaerobically codigested goat manure (GM) and harvest residues: corn stover (CS) and rice straw (RS). All digesters were operated simultaneously under mesophilic temperature of 40°C and notable phosphate solubilizing and nitrogen fixing bacterial populations indicated qualitative biofertilizer quality of the digestates. Codigestion of the substrates significantly increased biogas yield (p &lt; 0.05) compared to monodigestion, and the highest cumulative yield of 573 ml/g VS was obtained from codigested rice straw (RS) and goat manure (GM). With a significant decimation in number of pathogens (p &lt; 0.05), a 2 – 3 fold increase in populations of plant growth promoting bacteria (Bacillus and Pseudomonas species) was observed in digestate from codigestion assays when compared to monodigestion (control) and were identified as Clostridium sp., Bacillus subtilis, Bacillus megaterium, Lactobacillus sp., Pseudomonas fluorescens including methanogens: Methanothrix sp., Methanobacterium sp. and Methanosarcina sp. On the average, codigestion assays resulted in enhanced biogas yield and biofertilizer quality that was 2.3 – 4.1 times higher than single substrate digestion and generally improved the efficiency of biogas and biofertilizer production.</jats:p

Influence of storage containers on the physicochemical and microbiological (biofilm formation) indices of drinking water sources

ABSTRACT Effect of surfaces of earthenware pots, glass, plastic and stainless steel containers on the physicochemical and bacteriological (biofilm formation) quality of borehole and atmospheric water stored for twelve days were determined using standard analytical and bacteriological techniques. Susceptibility of the bacterial isolates to different antibiotics was also determined using standard Kirby-Bauer agar disc diffusion procedures. The physicochemical parameters determined for borehole water sample were within WHO permissible standard while rain water sample recorded slightly higher values for NO3 -, and NO2 -(10.2 mgL -1 and 0.045 mgL -1 respectively) than WHO standards of 10 mgL -1 and 0.02 mgL -1 respectively. Biofilm bacterial communities from stored borehole water consisted of nine genera including Pseudomonas, Micrococcus, Klebsiella, Bacillus, Staphylococcus, Escherichia, Proteus, Serratia, and Enterobacter. The recovery rate of the various bacterial genera were 40% in earthenware pot, 80% in plastic, 70% in stainless steel and 60% of the genera were isolated from glass container for stored borehole water. Fewer bacterial genera were isolated from stored atmospheric water and these included Pseudomonas, Bacillus, Staphylococcus, Streptococcus and Yersinia. The isolates were recovered at the rates of 40%, 80%, 60% and 40% in earthenware pot, plastic, stainless steel and glass containers respectively. While Escherichia coli, Yersinia sp and Pseudomonas aeruginosa exhibited remarkable sensitivity to Septrin (30 μg), Ampicillin (30 μg), Augmentin (30 μg) and Nalidixic acid (10 μg) as evinced by clear zones of inhibition, Enterobacter sp, Klebsiella sp and Proteus sp were moderately sensitive to some of the tested antibiotics. Amongst the gram positive bacteria, Micrococcus sp was most sensitive to the various antibiotics. Although Staphylococcus aureus showed resistance to most of the tested antibiotics, it was sensitive to Erythromycin (30 μg) and Chloramphenicol (30 μg). It could be deduced from the above results that the physicochemical and bacteriological quality of stored water are affected by both the source of the water and type of storage vessel. Although the effect of the vessels are not definitive, the levels of pH, Mg 2+ , NO2 -, NO3 -and hardness are enhanced in water stored in earthenware pots. The isolation of antibiotic resistant bacteria from stored water is of public health concern, thus, drinking water should not be held in containers for more than a day or two. Citation: Udofia GE, Ofon UA, Asamudo NU, Ndubuisi-Nnaji UU (2015). Influence of storage containers on the physicochemical and microbiological (biofilm formation) indices of drinking water sources

Metagenomic Study of Bacterial and Archaeal Populations during Anaerobic Digestion of Lignocellulosic Waste in Lab-scale Biogas Reactors

This study evaluated using 16S rDNA gene-based metagenomics technique the populations of bacteria and archaea in digestate samples from lab-scale anaerobic bioreactors digesting pretreated and untreated coconut husk fiber, pineapple floret and banana stem. Result of biodegradability experiment indicated high microbial activity in digestate (biogas slurry), with untreated banana stem having the highest total solids (TS) and volatile solids (VS) removal efficiencies of 78.3 % and 92.9 % respectively. Similarly, all pretreated substrates exhibited higher TS and VS losses with corresponding TS (77.8 %) and VS (87.2 %) removal efficiencies. This TS and VS removal rates signaled increased rate of organic matter decomposition with concomitant biogas productivity. Diversity comparisons performed between samples showed rich microbial diversity in untreated sample than the pretreated sample. Taxonomic composition revealed that, for untreated samples at the phylum level, the bacterial community was predominantly Firmicutes (relative abundance 97.0 %), with 0.30 % Actinobacteria and 0.10 % Proteobacteria. The genus Oxobacter (35.0 %), Clostridium (12.0 %) and Ethanoligenens (10.0 %) were ubiquitous and abundant in the untreated sample. The archaeal community was however dominated by the Euryarchaeota with one methanogenic order Methanomicrobiales, and a high abundance of the genera Thermacetogenium. For pretreated samples, at the phylum level, bacterial community was also dominated by Firmicutes (95.0 %), followed by Proteobacteria (1.02 %), Actinobacteria (0.18 %) and Tenericutes (0.06 %). The genus Clostridium (41.0 %), Ethanoligenens (29.0 %) and Lactobacillus (15.0 %) were also ubiquitous and abundant in the pretreated sample. Archaeal community was also dominated by Euryarchaeota with the two methanogenic orders Methanomicrobiales and Methanosarcinales dominating. The major microbial groups were hydrolyzing and fermenting populations. These findings revealed rich microbial assemblage and diversity among microbial communities in biogas digestate.</jats:p

Dynamics in Physicochemical and Bacteriological Properties of Simulated Leachate from Dump Site Soil in Ikhueniro, Benin City, Edo State, Nigeria

Study’s Excerpt • The physicochemical and microbiological properties of leachate from municipal solid waste (MSW) in Ikhueniro, Edo State, Nigeria was investigated. • Results revealed significant correlations between bacterial counts and the degradation of organic matter. • There is a need for improved waste management strategies in the area. Full Abstract Municipal solid waste (MSW) management in Nigeria faces significant challenges due to rapid urbanization and poor waste management practices.  Leachate, the liquid generated from MSW, poses a major pollution threat to natural resources, including surface and groundwater, and adversely affects human health and hygiene.  This study investigated the dynamics in physicochemical and microbiological properties of simulated leachate from dump site soil in Ikhueniro, Edo State, Nigeria using standard Microbiological testing techniques.  Samples were collected from a non-sanitary open dumpsite in Ikhueniro, Edo State, Nigeria, and leachate was obtained by filtering 150 g of waste-impacted soil mixed with sterile distilled water (1000 mL).  Over 28 days, microbial detection enumeration and physicochemical characterization were conducted on the filtrate leachate sample maintained in a rotary shaker at 28 °C and 150 rpm.  Results indicated high densities of microbial contamination with total heterotrophic bacteria (1.5±0.5 to 6.9±1.0 × 104 CFUmL-1) and coliform (2.7±0.8 to 7.8±1.0 × 103 CFUmL-1) counts.  These included potential pathogens like Klebsiella spp., Salmonella spp., Bacillus spp., Pseudomonas spp., and Yersinia spp.  Physicochemical analyses revealed significant (p<0.05) variations in parameters such as electrical conductivity (EC) with values ranging from 9183.3 –  9758.7µscm-1, total dissolved solids (TDS) with values ranging from 7004.0 – 8210.3 ppm, with changes in pH ranging from 6.48-7.62, biochemical oxygen demand (BOD) with values ranging from 561.7 – 651.3 mgL-1, and chemical oxygen demand (COD) with values ranging from 1981.7-2058.7 mgL-1.  The pH dropped from 7.62 to 6.48, and the levels of BOD and COD indicated a decreasing trend that was strongly and positively correlated (“r” ranging from 0.949 to 0.968) with bacterial counts, indicating organic molecule degradation.  This study underscores the environmental and public health risks posed by improperly managed waste and its resultant leachates while highlighting the potential for bioremediation strategies using isolated bacterial species.  Furthermore, transitioning to sanitary landfills and improving waste management practices are crucial for mitigating these risks

Improved biofertilizer properties of digestate from codigestion of brewer’s spent grain and palm oil mill effluent by manure supplementation

AbstractThe biofertilizer quality of anaerobically codigested agroindustrial residues from brewer’s spent grain and palm oil mill effluent was evaluated after supplementation with different livestock manure in order to validate its use as organic fertilizer. Manure supplementation assay was performed using different animal manure-inoculum to demonstrate the influence of inoculum-type on the nutrient status, plant growth promoting bacteria (PGPB) and other plant growth promoting attributes of the resultant digestate. In addition to elevated nutrient levels (K &gt; P &gt; Ca &gt; Mg &gt; S &gt; N), the plethora of essential microbial groups (phosphate solubilizers &gt; diazotrophs &gt; auxin producers) that enhance nutrition and promote plant growth was evinced in the supplemented digestate compared to the control. On the other hand, environmental risk assessment revealed a notable yet inadequate reduction in indicator bacteria and putative pathogens (&gt; 3.0 log CFU mL− 1) with potentially toxic elements within publicly available requirements. The preponderance of PGPB with excellent biofertilizing attributes observed in this study could be leveraged upon by plants thus substantiating its potential for use as organic fertilizer. However, the presence of pathogens highlights the importance of post-treatment hygienization to eliminate its biosafety risk.</jats:p

Enhanced Biogas Production from Anaerobic Codigestion of Lignocellulosic Waste for Efficient Bioenergy Utilization in Heating and Combustion Engine

Anaerobic digestion (AD) of lignocellulosic agro-waste such as coconut husk fibre, pineapple floret and banana stem was studied using standard protocols. A combination of physical, chemical and biological Pre-treatment was performed to facilitate the anaerobic digestion process. The experiment was carried out using laboratory-scale batch bioreactors maintained at 44.5 ± 2ºC and retention time of 25 days. Biogas production, pH, total and volatile solids concentrations (TS, VS) were also measured. With a general increase in pH after Pre-treatment of all substrates, biogas yield was significantly improved by 83.1% in all codigestion assays when compared to control (untreated substrates) with highest TS and VS removal rates of 77.7% and 87.2% respectively. In terms process performance, Pre-treatment of single substrate did not significantly improve AD of single substrates (coconut husk fibre/pineapple floret) and biogas production was inhibited in pre-treated banana stem. However, the highest biogas production with corresponding TS and VS removal rates of 78.3% and 92.9% respectively were obtained from untreated banana stem. Codigestion significantly enhanced biogas production that can be utilized for heating and knowledge of appropriate Pre-treatment choice is recommended to improve bioenergy production efficiency during anaerobic digestion.</jats:p