Characterization of brewery waste water and evaluation of its potential for biogas production

The issue of global warming and climate change is strongly receiving public attention and has become a major environmental concern both nationally and internationally. Brewing industries are among the largest consumers of water and the largest source of organic effluent mostly from the brewing, cleaning, and cooling processes which must be treated to allowable levels to reduce environmental pollution. Close to 10 L water is used for every 1 L beer that is brewed, though the amount of water in the final beer is small. A study was undertaken to characterize and assess the variations in the quality of untreated brewery waste water. Samples from different process streams including brewing line, clean in place line and mixing line from two brewing industries in Kenya were analyzed for BOD5, COD, TDS, TSS, sodium, total nitrogen and phosphorous using standard method as per American Public Health Association (APHA). There was a significant variation (p<0.001) in the all the physicochemical parameters between the industries and a significant interaction (p<0.001) between sampling point and the company. Analysis of the BOD to COD ratio showed the biodegradability index to range from 0.039 to 0.567 for brewing line, 0.177 to 0.766 for cleaning in place and 0.776 to 0.911 for mixing point, thus the waste water was found to be easily biodegradable at the mixing point for all the industries. However pretreatment would be required to improve anaerobic digestion

The Effect of Agricultural Soil Compaction on Physico-Mechanical Properties of Silt Loam Soils of Njoro, Kenya

In order to cope with the demand for more food for the ever growing world population, it has become necessary to intensify farming.Agrivultural machines movement across the field increases soil compaction. The objective of this study was to rstablish the effects of soil compaction 0n selected soil physico-mechanical properties. Afactorial experiment in a completely randomised design was used. Tests were conducted on 18 plots to investigate the effect of five tractor wheel pass treatments (1, 2, 3, 4, 5) and a no whool treatment on bulk density, penetration resistance, soil cohesion, angle of internal friction and soil shear strength at three depths (0 -20, 20 - 30 and 30 - 40 cm) with three replications per plot. The results showed that increasing the traffic wheel passes and depth resulted in  significant inccrease in bulk density (1291 to 1593 kg m-3), penetration resistance  (0.64 to 1,34 kPa), soil strength (121,20 to 156.97 kPa), angle of internal friction (29 to 350) and soil cohesion (5.84 to 8.42 kPa) at the 5% level of confidence.. Soil compaction was found to be a dynamic process transmitted to the lower depths through the soil matrix.It was concluded that althhough subsequent wheel passes hve  a smaller additional effect on the studied properties , it is cautioned that additional passes may lead to increased rillage requirements, &nbsp

Modelling Moisture Sorption Isotherms of Superabsorbent Polymer Fabric for Desiccant Drying of Crops

Desiccants are important in the drying of temperature-sensitive grains such as seeds for planting. Superabsorbent polymers (SAPs) have previously been identified for possible application in the drying of crops. Applying the gravimetric technique to measure the sorption isotherms and the effectiveness of the desiccant in crop drying was determined at temperatures 20, 25, 30, 35, 40, 45, 50, and 55°C. Using R statistical software, eleven sorption isotherm models were fitted to the experimental data using the nonlinear regression functions. The coefficients of each model were obtained. The modified Freundlich, modified Henderson, and modified Oswin models best predicted the experimental data for the study temperature range. Using symbolic regression and nonlinear regression in R software, four mathematical models were obtained. R software codes were assembled for the analysis of sorption isotherm models. Compared to the existing models, the developed models were found to give a more statistically accurate association between the temperature, moisture content of SAP fabric, and relative humidity

Isolation and characterization of methanogenic bacteria from brewery wastewater in Kenya

The production of biogas from renewable resources is becoming a prominent feature of most developed and developing countries of the world. A study was undertaken to characterize methanogenic microbial community found in brewery waste water. Their performance with regards to methane production was also studied. Thirty-two isolates were obtained using brewer thyglycollate agar medium. Characterization of the isolates was done by culture and biochemical methods. 65% of the isolates were found to be positive with Gram staining reaction, while 35% were negative. The isolates were identified by method of polymerase chain reaction (PCR). From the phylogenetic analysis, thirteen isolates were clustered into genus Bacillus sp., isolate 93b was closely related to Bacillus subtilis strain, while isolates 20a1, 171 and 7 closely related to Bacillus methylotrophicus isolate 10 was grouped together with Bacillus tequilensis, isolate 31 was clustered together with Bacillus licheniformis, while isolates 132, 252, 15, 262 and 182 were closely related to Lysinibacillus sp. and isolate 191 was clustered together with Lactobacillus casei. The study also shows that three isolates 32, 181 and 4 were closely related to Ralstonia pickettii, Providencia rettgeri and Myroides odoratimimus, respectively. The presence of isolates 201a, 171 and 7 with abilities to ferment different sugars, hydrolysis starch, liquefy gelatin, split amino acid tryptophan, produce catalase enzyme and hydrogen sulphide gas suggests their involvement in biogas production. The percentage methane content in the total gas produced at pH 8 varied significantly (p<0.001) for all the temperature ranges. The highest concentration of methane for most isolates was recorded at temperatures of 35 and 37°C for all the pH ranges.Key words: Biogas, characterization, methanogenic bacteria, pH, temperature, wastewater