Issue 1

This study was conducted to investigate the effect of different types of organic wastes (grass and newspaper wastes, cow dung and their combination) on physicochemical properties during vermicomposting using Eisenia fetida. Three set-ups were conducted in which three experiments were for composting (controls) indicated as C1 for newspaper waste, C2 for grass waste and C3 for cattle dung and the corresponding replicates for vermicomposting processes for grass and cattle dung were T1 to T7 and mixed of newspaper, grass and cattle dung were T8-T13. A significant difference was detected among weight and number of Eisenia fetida in treatments, which the highest weight and population growth of worms occurred in T7 (60% of newspaper, 30% of cattle dung and 10% of grass waste). Compared to control treatment (without earthworms), vermicomposting treatment resulted in a decrease of organic carbon and C/N ratio after 30 days. Vermicomposting caused significant reduction in organic carbon (3.9-32.8% ) and C/N ratio (7.9–33.6%). The heavy metals degradation was evaluated after 90 days and at the end of the experiment the concentration of As, and Cd significantly decreased. This study clearly indicates that vermicomposting is a suitable technology for bioconversion of newspaper waste, grass clipping and cow dung to valuable material.

Wastewater from textile industry is considered one of the major environmental challenges due to the large volume of highly colored, polluted and toxic effluent. This study investigated the treatability of real textile wastewater by pilot-scale anoxic-aerobic Membrane Bioreactor (MBR) system without sludge wasting for operation period of 100 days. The proposed system was investigated under different Internal Recycle (IR) ratios and the impact of IR ratio on Total Organic Carbon (TOC), Total Nitrogen (TN) and Color removals were examined. Under IR ratios between anoxic and aerobic tanks of 0.0, 0.5 and 2.0, the respective average removal efficiency of TN was 20.9%,53.4% and 71.7%, whereas average color removal of 81%, 85% and 88%, respectively was noted. The results indicated that increase of recycle ratio from 0.5 to 2.0 enhanced TN removal to about 71% and color removal to above 85%. The IR between anoxic and aerobic tanks has a significant role in TN and color removal due its effect on the development of bacterial communities. On the other hand, the results indicate over 93% TOC removal, which was independent of IR ratio.

In order to investigate the effect of treated wastewater on heavy metals and fecal coliform in plant and soil, a field experiment was conducted in RCBD with three treatments in four replications during 2016-2017 in Borkhar, Isfahan (Iran). Treatments including well water, semi-treated wastewater and combination of well water and wastewater were applied in consecutive cultivation of wheat and forage corn. The amount of heavy metals in the soil did not change after two seasons of wastewater application compared to well water. The amount of fecal coliform in both plants was increased in the irrigation water treatment compared to the well water, which was more evident in the corn plant, which is related to the high moisture content of this plant at harvest stage. Due to the improvement of soil nutrient concentrations after two seasons of continuous application of wastewater and no increase in the amount of heavy metals in the soil, the use of wastewater for agricultural production is permissible. But according to the fecal coliform index, it is recommended not to be used for the production of crops harvested at high humidity and conditions for the survival of pathogens.

The aim of this study is to investigate the effect of sub-irrigation with untreated and treated municipal wastewater on soil chemical parameters. Three treatments were used: untreated wastewater (U), treated wastewater (T) and tap water (W), being the control treatment, in two soil types, Sandy loam (SL) and Loamy sand (LS). A sub-irrigation system including pots filled with soil was installed in one of the greenhouses of the Agricultural University of Athens. The wastewater used was applied in the soil in pots at a depth of 10cm and 20cm. In order to determine the changes of chemical parameters at the point where the emitter was placed, the soil was divided into two zones according to depth: (zone I -upper) and (zone II-lower). The pH, CaCO3 %, K μg/g, Na μg/g, P μg/g and EC μmhos/cm, were determined. Statistically significant differences (p <0, 05) in sodium Na+ μg/g and electrical conductivity EC were observed, only in LS soil. Phosphorus and sodium increased in zone (I) for SL soil (p <0, 05). Electrical conductivity and potassium increased in zone (I), while CaCO3% and pH increased in zone (II) for LS soil (P <0, 05).