Evaluation of stability parameters in in-vessel composting of municipal solid waste

Composting is a reliable technology for production of stabilized organic matter that is suitable for agriculture, but this process should be carefully monitored with appropriate indices. Quality of compost is important from maturity and stability viewpoint, but in most compost factories proper attention is not paid to it. This study was designed to evaluate the stability indices in municipal solid waste composting, for selecting the best index in quality monitoring of the wastes. Processed and shredded municipal solid waste from Isfahan compost plant was used as raw material in an in-vessel composting process. A cylindrical reactor with 1 m height and 50 cm diameter made of Pyrex glass was designed. Air was supplied at a specifically flow rate 0.2 L/min.kg to maintain aerobic condition. NH[4][+]/ NO[3] ratio, dehydrogenase enzyme activity [DA], pH, oxidation reduction potential [ORP or Eh] and specific oxygen uptake rate [SOUR] were used as stability indices. These parameters were measured during 40 days of composting process. Changes in these parameters during this period were surveyed and analyzed. Statistical analysis was carried out to choose best of them. Results showed that among the indices, SOUR can show the different stages of microbial decomposition and a numerical value for compost stability also SOUR value less than 2 mg O[2]/gVS.h can show the full stability of compost

Performance of moving bed biofilm reactors for biological nitrogen compounds removal from wastewater by partial nitrification-denitrification process

In this research, the continuously operated laboratory scale Kaldnes [k1] moving bed biofilm reactors [MBBRs] under partial nitrification-denitrification process were used for treatment of synthetic wastewater containing ammonium and glucose. The Anoxic and Aerobic reactors were filled to 40 and 50% [v/v] to attach and retain biomass with k1 biofilm carriers, respectively. The favorite internal recycle ratio and hydraulic residence time [HRT] to eliminate nitrogen compounds were 300% of inflow rate and 20 hours, respectively. Optimal dissolved oxygen [DO] was 1-1.5 mg/L in the aerobic reactor. No sludge was returned into the system and only an internal recycling was performed from aerobic to anoxic reactor. The results showed that the maximum and average specific nitrification rate [SNR] in the aerobic reactor were 49.4 and 16.6 g NOx-N/KgVSS.day, respectively and the maximum and average specific denitrification rate [SDNR] as 156.8 and 40.1gNOx-N/KgVSS.day in the anoxic reactor, respectively. The results also showed that it is possible to reach a stable partial nitrification with high ratio of NO2-N/NOx-N [80% to 85%] during high load ammonium and low DO concentration [<1.5 mg/L] in the aerobic reactor. During optimum conditions, the average removal efficiency of total nitrogen [TN], ammonia and soluble organic carbon [SCOD] occurred as 98.23%, 99.75% and 99.4%, respectively. This study showed that the partial nitrification/denitrification process in the moving bed biofilm reactors system has an acceptable performance for treatment of wastewater with high load of organic carbon and organic nitrogen compounds

[Evaluation of the influence of conventional water coolers on drinking water quality]

Drinking water quality after treatment and before reaching the consumer could be affected by distribution pipes, service lines and Home devices. The structure of water coolers, a home device that are widely used in warm months of the year, could potentially affect the quality of drinking water. The aim of this study was to assess the microbial and chemical quality of water from conventional water coolers. Water samples were collected from 29 water cooler systems at the Isfahan university of medical sciences. 29 control samples also obtained from the nearest drinking water taps. All samples were examined for total heterotrophic bacteria and physicochemical parameters including temperature, ph, turbidity and heavy metals. All samples from the water cooler systems complied with the EPA guidelines for total heterotrophic bacteria count. There were no significant differences between the levels of heavy metals in water samples from the water cooler systems and taps. There was only a significant difference between the level of Cu in the water samples from cooler systems and taps The overall results of this study indicated that the use of water cooler systems from hygienic point of view could not cause any problems for consumers

Removal of cadmium and humic acid from aqueous solutions using surface modified nanozeolite A

The sorption of cadmium and humic acids from aqueous solutions using surface-modified nanozeolite A has been investigated under various examination conditions. The morphology of untreated and treated nanozeolite was studied under scanning electron microscope and transmission electron microscope. Isotherms of cadmium adsorption onto surface-modified nanozeolite A were studied at different pH, solid to liquid ratio, adsorbate concentration and interaction time. Kinetic and equilibrium studies were conducted and the equilibrium data have been analyzed using Langmuir and Freundlich isotherm models. The study revealed that experimental results were in agreement with the Freundlich model. The Langmuir monolayer adsorption capacity was found to be 1666.67 g cadmium and 6.75 g humic acid per gram of modified nanozeolite A, which is higher than that of reported value for other zeolites. The sorption ability was enhanced by surface modification and reduction in size and enabled the zeolite to adsorb cadmium. The adsorption of cadmium and humic acid on nanozeolite was found to be the highest at pH 6 and 3, respectively. Results showed that solid to liquid ratio and pH are the most important factors for cadmium and humic acid removal, respectively. Effect of competitive ions was studied and results showed that there is no competition between cadmium and humic acid sorption and presence of these ions

Rapid monitoring of indicator coliforms in drinking water by an enzymatic assay

Coliform group has been extensively used as an indicator of drinking water quality and historically led to the public health protection concept. Multiple tube fermentation technique has been currently used for assessment of the microbial quality of drinking water. This method, however, has limitations. Enzymatic assay constitute an alternative approach for detecting indicator bacteria, namely total coliforms and E.coli in various aquatic environments. This study compared the performance of LMX broth as an enzymatic assay with the standard methods multiple tube fermentation technique and presence-absence test, for the detection of indicator coliforms in drinking water samples. In addition, the potential effect of water quality on the microbial detection method was assayed through measurement of some physicochemical parameters. From the 50 drinking water samples tested, 8 [16%] and 7 [14%] contained total coliforms and E.coli as indicated by all three techniques. Although on average the LMX recovered more total coliforms and E.Coli numbers comparing to multiple tube fermentation, but there was no significant difference. A significant difference existed between the level of residual chlorine for positive and negative samples. In conclusion, enzymatic assay showed a rapid and less labor method, allowing the simultaneous detection of total coliforms and E.coli. The method is particularly useful in the early warning of fecal pollution of drinking water

Detection of phenol degrading bacteria and Pseudomonas putida in activated sludge by polymerase chain reaction

Phenol is one of the organic pollutants in various industrial wastewaters especially petrochemical and oil refining. Biological treatment is one of the considerable choices for removing of phenol present in these wastewaters. Identification of effective microbial species is considered as one of the important priorities for production of the biomass in order to achieve desirable kinetic of biological reactions. Basic purpose of this research is identification of phenol-degrading Pseudomonas Putida in activated sludge by polymerase chain reaction [PCR] that has high speed and specificity. In this research, 10 various colonies of phenol-degrading bacteria were isolated from municipal activated sludge and the rate of phenol removal and growth rate of these bacteria were assessed in different concentrations of phenol [200 - 900 mg/L]. Confirmation of the largest subunit of multicomponent phenol hydroxylase [LmPH] gene and gene coding the N fragment in Pseudomonas Putida-derived methyl phenol operon [DmpN gene] through PCR were used for general identification of phenol-degrading bacteria and Pseudomonas Putida, respectively. Presence of a 600 bp [base pairs] bond in all of isolated strains indicated that they contain phenol hydroxylase gene. 6 of 10 isolated bacteria were Pseudomonas Putida because they produced a 199 bp PCR product by DmpN primers. According to PCR results in this study, the best phenol-degrading bacteria that can utilize 500 - 600 mg/L phenol completely after 48 hours incubation, belong to Pseudomonas Putida strains. It is clear that use of isolated bacteria can lead to considerable decrease of treatment time as well as promotion of phenol removal rate

Effectiveness of chitosan as natural coagulant aid in treating turbid waters

During the last decade, there has been a concern about the relation between aluminum residuals in treated water and Alzheimer disease, and more interest has been considered on the development of natural coagulants such as chitosan. Chitosan, a natural linear biopolyaminosaccharide, is obtained by alkaline deacetylation of chitin. The present study was aimed to investigate the effects of alum as coagulant in conjunction with chitosan as coagulant aid on the removal of turbidity, hardness and Escherichia coli from water. A conventional jar test apparatus was employed for the tests. The optimum pH was observed between 7 to 7.5 for all turbidities. The optimum doses of alum and chitosan when used in conjunction, were 10mg/L and 1mg/L, 5mg/L and 0.5mg/L, and 5mg/L and 0.5mg/L in low, medium and high turbidities, respectively. Turbidity removal efficiency was resulted between%74.3 to%98.2 by alum in conjunction with chitosan. Residual Al[+3] in treated water was less than 0.2 mg/L, meeting the international guidelines. The results showed that turbidity decrease provided also a primary Escherichia coli reduction of 2-4 log units within the first 1 to 2 hr of treatment. Hardness removal efficiency decreased when the total hardness increased from 102 to 476mg/L as CaCO3. At low initial turbidity, chitosan showed marginally better performance on hardness, especially at the ranges of 100 to 210 mg/L as CaCO3. In conclusion, coagulant aid showed a useful method for coagulation process. By using natural coagulants, considerable savings in chemicals and sludge handling cost may be achieved

Evaluation of QIAamp DNA mini kit for removing of inhibitors in detection of Cryptosporidium parvum oocysts in water samples by a nested- PCR assay

In recent years, there has been a dramatic increase in the occurrence of waterborne disease outbreaks caused by the Cryptosporidium parvum, and presence of this protozoan parasite in drinking water is a significant health problem faced by the water industry. A new strategy for detection of Cryptosporidium oocysts in water samples is PCR' based techniques. In this study a nested' PCR assay was designed for the specific amplification of a 199 bp DNA fragment of the gene encoding the heat shock protein [hsp70] of Cryptosporidium parvum oocysts. In order to prevent the inhibition of PCR amplification by substances contained in water samples, three DNA purification methods including QIAamp DNA mini kit, InstaGene Matrix, MagExtractor ' Genome were compared in concentrates of tap water samples spiked with the oocysts. After it was found that the QIAamp is only efficient purification technique, the efficiency of QIAamp and immunomagnetic separation for nested'PCR assay of various water samples was compared. The results show that QIAamp provide a useful and rapid tool for removing of PCR inhibitors. It seems that QIAamp purification- nested PCR assay is a sensitive, rapid and cost effective method for detection of Cryptosporidium parvum oocysts in clean water samples with turbidity < 2 nephelometric turbidity unit [NTU]

nested-PCR assay for detection of cryptosporidium parvum oocysts in water samples

Cryptosporidiosis is a gastroenteric disease caused by the protozoan parasite Cryptosporidium parvum. Water-borne transmission of this organism has become more prevalent in recent years. Current method for detection of C. parvum oocysts in water is immunofluoresence assay [IFA]. The method is time consuming, laborious and particularly not-specific. It cannot determine the infectivity of detected oocysts. We have evaluated a nested- PCR assay for sensitive detection of C. parvum oocysts in water samples. Water sample concentrates were spiked with Cryptosporidium oocysts and after DNA extraction and purification by QIAamp DNA mini kit, detection was achieved by nested PCR amplification of a 200 bp region of hsp70 gene specific for C. Parvum. The method could detect as few as one oocyst in seeded tap water samples. On the basis of these results, PCR could be a useful tool in the monitoring of water samples for the detection of Cryptosporidium oocysts

study of the necessity of librarians and medical informants cooperation in approved research plans from research executers point of view in 2003

The scientific, technical, economic and social development of a society is closely connected to the amount of information produced by its managers, researcher and scholars. In this study, the necessity of the librarians and medical informants' cooperation in the approved research plans of IUMS was investigated. It was a descriptive study in which the participants were 96 research executives who performed research in 2003 under he supervision of Isfahan University of Medical Sciences research deputy. The data were collected by a questionnaire which was checked for its validity and reliability. The findings revealed that 81.3% of the research executives asserted that it was necessary to have access to librarians and medical informants in a research team. Regarding the positive views of research executives, it was suggested that it would be essential to have contact with librarians and medical informants and to consult with a statistical advisor