الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 229 |  |  |
| | | from | 229 | | |
Abstract
The disposal of wastewater without treatment could create a great threat to living beings and the environment. Paper recycling industry is heavy consuming industry of the water causing wastewater that characterized by increased BOD,COD, TS, and TDS. Consequently, the discharge of this contaminated water can cause a serious problems to the sewer system in which it is disposed, and to the environment (Nile and coastal environments). The treatment of this wastewater can be accomplished through primary treatment consisting of neutralization, screening, sedimentation, and floatation. In addition, biological treatment are such as aerated stabilization basins and activated sludge, reduces the organic content Furthermore, chemical oxidation technologies are effective and promising applications for the wastewater treatment such as ozonization.
Nanotechnology has a great potential in enhancing water and wastewater treatment due to low cost, reuse and highly efficient in removing the pollutants. Iron nanoparticles have several advantages due to their stability, low cost of preparation, biocompatibility and their manipulation by a magnetic field. Green synthesis of nanoiron (biosynthesis) is considered the most efficient way of nanoiron production because it is cost effective, stable produced nanoiorn, less toxic and easy. They are widely used in remediation of industrial sites contaminated with organic compounds.
The main aim of this study is to assess the efficiency of bio-synthesized nano iron in treatment of paper recycling plants wastewater.
The study was conducted by collecting and analysis wastewater from El Dar El Beida paper recycling plant in Alexandria, and collecting three different environmental samples from which bacteria- producing nano iron were isolated. The obtained strains producing nanoiron were isolated, they were tested under different incubation time and different modified Luria broth. After that, the best strain isolate was examined in third modified luria broth after three days under different optimizations conditions (temperature, state, pH, iron salts ratio and amount and media amount) for the best bacterial growth and nanoiron production.
X4 under the best optimization conditions was used in treatment of wastewater of paper recycle plant by three different ways (bacterial biomass, culture supernatant and extracted nanoiron) with different doses and at different detention time. The effect of these treatment methods was tested according to COD reduction. The best treatment method with best dose at the best detention time among them was applied in wastewater remediation according to the proper statistical analysis. Afterward, the treated wastewater was physically and chemically analyzed and compared with environmental laws (93, 48, 4).
The results of the study are summarized in the optimization of bacterial growth and nanoiron production, then examination of nano iron produced by the best strain (X4), then effect of treatment methods using X4 (A,B, and C) in reducing COD of paper recycling wastewater to comply with environmental laws determining the optimum dose among three different treatment methods, followed by selecting the best method, dose and time in
Summary
111
treatment of paper recycling plant wastewater by statistical analysis of the results, and finally applying the best treatment method (C) with the best dose (L2) at the first day in treatment of wastewater from paper recycling plant.
The effect of different incubation time (1-9 days) and three different media (M1,M2,M3) on nanoiron synthesis by the five isolated strains (X1,X2,X3,X4,X5) was tested. According to UV-Visible Spectroscopy analysis, it was observed that X4 among the five isolated strains had the highest absorbance in M1, M2 ,and M3 (2.82 and 2.75 , 2.449 , 2.015 respectively) at the third day, but the highest absorbance among them was in M1 (2.82 and 2.75 ) at third day.
This suggested X4 that had the highest nanoiron production in M1 at third day. Otherwise, the highest pH value was 10.30 of X4 in M3 at third day. Moreover, the highest intensity was 3530 (at 2Ɵ = 37.255°) of X4 in M1at third day using XRD. For the confirmation of the best media, the nanoiron showed the highest percentage in M3, was 12.97% using SEM-EDX examination. Therefore, it was concluded that X4 was the best strain in M3 at the third day. The effect of different temperature (25, 30, 37, 42OC) at shaking and static states on nanoiron synthesis was tested reporting that X4 had the highest absorbance (at 2) using UV-Visible Spectroscopy analysis at 30 OC in shaking state in M3 after third day. Besides, the highest pH was 7.38 at 30 OC in shaking state. Afterward, the effect of different pH (4, 6, 7, 8, 10, 12, 14) on nanoiron synthesis was examined resulting in X4 introduced the highest absorbance (around 2) using UV-Visible Spectroscopy analysis at pH 7 and 10 in M3 at 30 OC in shaking state after third day. For the reason that, the pH 7 represented the neutral one and for decreasing the usage of NaOH, it was the prefered pH.
Subsequently, the effect of different iron salt ratio(FeSO4:FeCl3) with the following ratio: 0.5:1, 1:2, 2:4, and 4:8 on nanoiron synthesis was examined finding that X4 introduced the highest absorbance (1.922) using UV-Visible Spectroscopy analysis at FeSO4:FeCl3 –1:2 in M3 at 30 OC in shaking state at pH 7 after third day. Thereafter, the effect of different amount of 1:2 iron salt ratio(1.5, 2, 2.5,3,3.5,4 ml) after third day in M3 at 30 OC in shaking state at pH 7 on nanoiron synthesis was tested resulting in X4 introduced the highest absorbance (1.915) using UV-Visible Spectroscopy analysis with 2.5 ml amount of iron ratio of FeSO4 : FeCl3 = 1:2.
Later, the effect of different amount of M3(50 (20%),100 (40%),150 (60%),200 (80%) ml) after third day at 30 OC in shaking state at pH 7 with 2.5 ml amount of iron ratio of FeSO4 : FeCl3= 1:2 on nanoiron synthesis was examined showing that X4 introduced the highest absorbance where the amount of M3 media was 200 ml (80%). Where, the amount of the media could represent the remaining empty part of the flask (250ml).
The examination of nanoiron produced by X4 in three treatment methods (bacterial biomass (first treatment method (A)), supernatant (second treatment method(B)), and extracted nanoiron (third treatment method (C)) was done. Where, C had the highest percentage of nanoiron (at the optimized conditions), which was 52.45% , followed by bacterial biomass (A) which had 42.8% of nanoiron production using Electron Microscopy-Energy Dispersive X-ray analysis (SEM-EDX). Moreover, Transmission Electron Microscopy (TEM), showed that the intercellular nano iron was produced inside X4 cells at 80Kv.
Summary
112
The excessive production of nanoiron led to the destruction of bacterial cells of X4 releasing interacellular nanoiron at 80Kv. The intercellular produced of nanoiron had nano sized 8.68, 9.37,115, 15.8 and 20.9 n.m at 80 Kv. The extracellular produced nanoiron in supernatant was released after centrifugation of bacterial culture and may be due to destruction of bacterial cells by heavy nanoiron production at 80Kv. The sonicated X4 biomass released intercellular nanoiron at 80Kv.
The effect of treatment methods (A,B, and C) with six different doses or concentration in reducing COD of paper recycling wastewater to comply with environmental laws was examined, and indicated that the bacterial biomass (0.61 g) was the best in COD reduction from 1625 ppm to 1100 ppm after the first day. For the supernatant concentration (B), it was noticed that the supernatant concentration (5ml) had the best reduction of COD from 1625 ppm to 900 ppm after the sixth day.
For extracted nanoiron concentration (C), it was signified that the extracted nanoiron concentration (15ml) had the highest COD reduction from 1625 ppm to 800 ppm after the first day. Among these three chosen method and dose , the extracted nanoiron concentrations (15ml) was the best as it reduced COD from 1625 ppm to 800 ppm after the first day. Concerning environmental laws (93, 48,4), these chosen method and dose complied with law 93 after first day, but did not comply with law 48 and law 4. However, the bacterial biomass (0.61 g), and the extracted nano iron concentrations (15ml) could comply with the law 48 and Law 4 after eighth day and seventh day respectively.
For the confirmation of the optimum method and dose among three different treatment methods, the best bacterial biomass (0.61 g), the best supernatant concentration (5ml) , and the best extracted nano iron concentrations (15ml) were tried again ensuring the previous results by taking the biomasses before and after the best bacterial biomass (0.305, 1.21 g) and the concentrations before and after the best concentration in case of supernatant (2.5,10 ml) and extracted nanoiron (10, 20 ml) to determine the best one among them all.
Results suggested that CL2 was the best in COD reduction at different detention time (first , second and third days ). Therefore, CL2 was the best one in diminution of COD at first day (for reducing time) on complying with Law 93 , but did not complied with law 48 and law 4 even after third day. Among all treatment methods (A,B,C) with different doses (L1, L2,L3) at different detention time (first, second, and third days) , the highest removal percentage was by Cl2 at first, second, and third day (70.74%, 73.62%, and 81.16% respectively). Even though, CL2 at first day was preferred for time reduction and it gave COD values below the limit (1100ppm) of law 93/1962.
Statistical analysis suggested that the interaction between independent variables (time and method-dose) were estimated by the analysis of variance (ANOVA) and the main effect (COD reduction) was identified based on P-value (˂ 0.05) with ≥ 95 % of confidence level Where, the best detention time was at third day and the best method-dose treatment was CL2.
For the reason that there was a significance interaction between time and methoddose (P-value ≤ 0.05), the data was gathered in the form of “time–method–dose” resulting in 36 different treatment method. Afterward, the data was tested with Shapiro –Wilk test, Levene Statistic, and one-way ANOVA. As the absence of homogeneity of data, Kruskal
Summary
113
Wallis was used as non parametric alternative and for confirmation of the best treatment method depending on rank. As there was no considerable difference between different detention time (First day, Second day, Third day) of CL2. Therefore, the First day CL2 was considered the best treatment method to diminish time consumption.
Afterward, 36 treatments divided into 14 group in line with their complying with law 93 (COD= 1100 ppm) by using Duncan test (pair wise comparison), it was observed that the groups from 1 to 8 were acceptable. However, there was a difference between first day CL2 (third group), second day CL2 (second group), and third day CL2 (first group) treatment methods in COD mean which were 485.33, 437.50 and 312.42 ppm respectively. Nevertheless for saving time, First day CL2 (third group) was considered the most preferred treatment method with acceptable value (in comparison with law 93 of 1962) and minimum time consumption.
The application results of the best treatment method (C) with the best dose (L2) for one day which was the best (extracted nanoiron) in treatment of the tested wastewater as mentioned before, revealed that values of each COD, BOD, TSS, TDS were lower than control (before application). The results showed that heavy metals (Pb, Fe, Cd) was within acceptable limit before treatment. Otherwise, the iron concentration increased after treatment. While, oil and grease was higher than acceptable limit before treatment and increased after treatment.
In comparison with Law 93 of 1962 (decree No. 44 for year 2000), it was observed that the BOD, COD, TSS, TDS, Cd, and Pb parameters were within acceptable limits. On the other hand, oil and grease was higher than acceptable limit (100 ppm), and iron had an elevation but it was not mentioned in this law. However, the treated sample did not comply with law 48 and law 4, as it had higher concentration of BOD, COD, TSS, Oil and grease, and iron.
This study recommended using the Ochrobactrum sp.X4 in nano iron formation, avoid nanoiron application for longer time (more than eight days) in treatment due to ineffectiveness of nanoiron (aggregates), and getting benefit of recyclability characteristic of nanoiron in several cycles of wastewater treatment. The further studies will be on using biomass, and supernatant of Ochrobactrum sp.X4 in wastewater treatment.