Ethanol production from potato peel waste (PPW)

Considerable concern is caused by the problem of potato peel waste (PPW) to potato industries in Europe. An integrated, environmentally-friendly solution is yet to be found and is currently undergoing investigation. Potato peel is a zero value waste produced by potato processing plants. However, bio-ethanol produced from potato wastes has a large potential market. If Federal Government regulations are adopted in light of the Kyoto agreement, the mandatory blending of bio-ethanol with traditional gasoline in amounts up to 10% will result in a demand for large quantities of bio-ethanol. PPW contain sufficient quantities of starch, cellulose, hemicellulose and fermentable sugars to warrant use as an ethanol feedstock. In the present study, a number of batches of PPW were hydrolyzed with various enzymes and/or acid, and fermented by Saccharomyces cerevisae var. bayanus to determine fermentability and ethanol production. Enzymatic hydrolysis with a combination of three enzymes, released 18.5 g L^?1 reducing sugar and produced 7.6 g L^?1 of ethanol after fermentation. The results demonstrate that PPW, a by-product of the potato industry features a high potential for ethanol production.     

Waste paper and clinoptilolite as a bulking material with dewatered anaerobically stabilized primary sewage sludge (DASPSS) for compost production

Environmental problems associated with sewage sludge disposal have prompted strict legislative actions over the past few years. At the same time, the upgrading and expansion of wastewater treatment plants have greatly increased the volume of sludge generated. The major limitation of land application of sewage sludge compost is the potential for high heavy metal content in relation to the metal content of the original sludge. Composting of sewage sludge with natural zeolite (clinoptilolite) can enhance its quality and suitability for agricultural use. However, the dewatered anaerobically stabilized primary sewage sludge (DASPSS) contained a low concentration of humic substances (almost 2%), and the addition of the waste paper was necessary in order to produce a good soil conditioner with high concentrations of humics. The final results showed that the compost produced from DASPSS and 40-50% w/w of waste paper was a good soil fertilizer. Finally, in order to estimate the metal leachability of the final compost product, the generalized acid neutralization Capacity (GANC) procedure was used, and it was found that by increasing the leachate pH, the heavy metal concentration decreased. The application of the sequential chemical extraction indicated that metals were bound to the residual fraction characterized as a stabilize fractions.     

Electrochemical detoxification of four phosphorothioate obsolete pesticides stocks

The phosphorothioate pesticides are widely used for crop production and fruit tree treatment, but their disposal causes serious environmental problems. Four commercial phosphorothioate pesticides (Demeton-S-methyl, Metamidophos, Fenthion and Diazinon) were treated by an electrolysis system using Ti/Pt as anode and stainless steel 304 as cathode. A number of experiments were run in a laboratory scale pilot plant and the results are presented. For Fenthion the achieved reduction was over 60%, while for Demeton-S-methyl, Metamidophos and Diazinon was more than 50%. Diazinon had the lowest energy demand. The COD/BOD5 ratio was improved considerably after electrolysis for all four pesticides examined. As a conclusion, electrochemical oxidation could be used as a pretreatment method of the pesticides detoxification.     

Treatment of olive mill waste water with activated carbons from agricultural by-products

A series of activated carbons prepared by a two-step steam activation of olive stone and solvent extracted olive pulp (SEOP) have been used in an attempt to investigate the total phenol removal and chemical oxygen demand (COD) decrease in olive mill waste water (OMWW). The temperature of carbonization and activation were kept constant at 850 and 800 degrees C, respectively. One of the carbons was prepared by a single-step process at 800 degrees C. Activated carbons have been characterized by adsorption of N2 at 77 K and mercury porosimetry. Their iodine values were also determined. Surface oxides of activated carbons were determined using the Boehm's method. The porosity development and the surface chemistry of carbons were correlated to increasing removal ability of organic molecules. Kinetics of adsorption was evaluated by applying the Lagegren model while adsorption isotherm data were fitted to Langmuir model. Mesoporosity seems to be the key factor for total phenol removal while micoporosity controls the adsorption of total organics as expressed by the COD decrease in OMWW. For carbons with similar structure, the adsorption of phenols or total organics might be affected by the presence of carbonyls.     

Conversion of brewers’ spent grain into proteinaceous animal feed using solid state fermentation

Environmental Science and Pollution Research - Brewers’ spent grain (BSG) represents the 85% of the total residue produced during the beer brewing process, with a global annual production...