Abstract: 40L of hollow fiber membrane bioreactor with solids retention times (SRT) of 30, 15 and 4 days were setup for treating synthetic wastewater at hydraulic retention times (HRT) of 12, 8 and 4 hours. The objectives of the study were to investigate the effects of SRT and HRT on membrane fouling. A comparative analysis was carried out for physiochemical quality parameters (turbidity, suspended solids, COD, NH3-N and PO43-). Scanning electron microscopy (SEM), energy diffusive X-ray (EDX) analyzer and particle size distribution (PSD) were used to characterize the membrane fouling properties. The influence of SRT on the quality of effluent, activated sludge quality, and membrane fouling were also correlated. Lower membrane fouling and slower rise in trans-membrane pressure (TMP) were noticed at the longest SRT and HRT of 30d and 12h, respectively. Increasing SRT results in noticeable reduction of dissolved organic matters. The best removal efficiencies of COD, TSS, NH3-N and PO43- were 93%, 98%, 80% and 30% respectively. The high HRT with shorter SRT induced faster fouling rate. The main fouling resistance was cake layer. The most severe membrane fouling was observed at SRT and HRT of 4 and 12, respectively with thickness cake layer of 17mm as reflected by higher TMP, lower effluent removal and thick sludge cake layer.
Abstract: The heavy metals pollution in water, sediments and fish of Lake Manzala affected form the disposal of wastewater, industrial and agricultural drainage water into the lake on the environmental situation. A pilot plant with an industrial discharge flow of 135L/h designed according to the activated sludge plant to simulate between the biological and chemical treatment with the addition of alum to the aeration tank with dosages of 100, 150, 200 and 250 mg/L. The industrial discharge had concentrations of Lead and BOD5 with an average range 1.22, 145mg/L respectively. That means the average Pb was high up to 25 times than the allowed permissible concentration. The optimization of the chemical-biological process using 200mg/L Alum dosage compared has improvement of Lead and BOD5 removal efficiency to 61.76% and 56% respectively.
Abstract: The aim of the study is to improve removal of trace organic contaminants dissolved in activated sludge by the process of filtration with membrane bioreactor combined with modified activated carbon, for a maximum removal of organic compounds characterized by low molecular weight. Special treatment was conducted in laboratory on activated carbon. Tow reaction parameters: the pH of aqueous middle and the type of granular activated carbon were very important to improve the removal and to motivate the electrostatic Interactions of organic compounds with modified activated carbon in addition to physical adsorption, ligand exchange or complexation on the surface activated carbon. The results indicate that modified activated carbon has a strong impact in removal 21 of organic contaminants and in percentage of 100% of the process.
Abstract: The present study is aimed at alteration of sewage sludge into stable compost product using vermicomposting of sewage sludge mixed with cattle manure and saw dust in five different proportions based on C/N ratios (C/N 15 (R1), 20 (R2), 25 (R3) and 30 (R4); and control (R5)) by employing an epigeic earthworm Eisenia fetida. Higher reductions in C/N ratio, CO2 evolution and OUR were observed in R4 demonstrated the compost stability. In addition, R4 proved to be best combination for the growth of the earthworms. In order to observe the optimal degradation, kinetics for degradation of organic matter in vermicomposting were quantitatively evaluated. An approach model was developed by assuming that composting process is carried out in a homogeneous way and the kinetics for decomposition reaction is represented by a Monod-type equation. The results exhibit comparable variations in the kinetic constants Km and K3 under varying parameters during vermicomposting process. Results suggested that higher R2 value in R4, enhanced suitability towards Lineweaver-Burke plot. R4 yields higher degradability coefficient (K) reveals that the occurrence of optimal nutrient balance, which not only enhanced the affinity of enzymes towards substrate but also improved its degradation process. Therefore, it can be proved that R4 provided to be the best feed combination for vermicomposting process as compared to other reactors.
Abstract: The efficiency of heavy metals removal from sewage
sludge in bioleaching processes with heterotrophic, chemoautotrophic
(sulphur-oxidizing) sludge cenoses and chemical leaching (in
distilled water, weakly acidic or alkaline medium) was compared.
The efficacy of heavy metals removal from sewage sludge varies
from 83 % (Zn) up to 14 % (Cr) and follows the order: Zn > Mn > Cu
> Ni > Co > Pb > Cr. The advantages of metals bioleaching process
at heterotrophic metabolism were shown. A new process for
bioconversation of sewage sludge into fertilizer at middle
temperatures after partial heavy metals removal was developed. This
process is based on enhancing vital ability of heterotrophic
microorganisms by adding easily metabolized nutrients and synthesis
of metabolites by growing sludge cenoses. These metabolites possess
the properties of heavy metals extractants and flocculants which
provide the enhancement of sludge flocks sedimentation. The process
results in biomineral fertilizer of prolonged action with immobilized
sludge bioelements. The fertilizer satisfies the EU limits for the
sewage sludge of agricultural utilization. High efficiency of the
biomineral fertilizer obtained has been demonstrated in vegetation
experiments.
Abstract: The effect of polyelectrolytes; cationic and anionic charges and coagulants have been investigated for fresh activated sludge at different concentrations and pH values in a comparative fashion. The results from the experiments indicate that the cationic polyelectrolytes have a significant effluence on the sludge characteristic, degree of flocculation and water quality such as turbidity and SVI. The results show that the cationic CPAM-80 is the most effective polyelectrolyte used corresponding to turbidity and SVI despite of the variations in feed properties of the fresh activated sludge.
Abstract: Heavy metal transfer in soil profiles is a major
environmental concern because even slow transport through the soil
may eventually lead to deterioration of groundwater quality. The use
of sewage sludge and effluents from wastewater treatment plants for
irrigation of agricultural lands is on the rise particularly in peri-urban
area of developing countries. In this study soil samples under sludge
application and wastewater irrigation were studied and soil samples
were collected in the soil profiles from the surface to 100 cm in
depth. For this purpose, three plots were made in a treatment plant in
south of Tehran-Iran. First plot was irrigated just with effluent from
wastewater treatment plant, second plot with simulated heavy metals
concentration equal 50 years irrigation and in third plot sewage
sludge and effluent was used. Trace metals concentration (Cd, Cu)
were determined for soil samples. The results indicate movement of
metals was observed, but the most concentration of metals was found
in topsoil samples. The most of Cadmium concentration was
measured in the topsoil of plot 3, 4.5mg/kg and Maximum cadmium
movement was observed in 0-20 cm. The most concentration of
copper was 27.76mg/kg, and maximum percolation in 0-20 cm.
Metals (Cd, Cu) were measured in leached water. Preferential flow
and metal complexation with soluble organic apparently allow
leaching of heavy metals.
Abstract: Ever since industrial revolution began, our ecosystem
has changed. And indeed, the negatives outweigh the positives.
Industrial waste usually released into all kinds of body of water, such
as river or sea. Tempeh waste is one example of waste that carries
many hazardous and unwanted substances that will affect the
surrounding environment. Tempeh is a popular fermented food in
Asia which is rich in nutrients and active substances. Tempeh liquid
waste- in particular- can cause an air pollution, and if penetrates
through the soil, it will contaminates ground-water, making it
unavailable for the water to be consumed. Moreover, bacteria will
thrive within the polluted water, which often responsible for causing
many kinds of diseases. The treatment used for this chemical waste is
biological treatment such as constructed wetland and activated
sludge. These kinds of treatment are able to reduce both physical and
chemical parameters altogether such as temperature, TSS, pH, BOD,
COD, NH3-N, NO3-N, and PO4-P. These treatments are implemented
before the waste is released into the water. The result is a
comparation between constructed wetland and activated sludge,
along with determining which method is better suited to reduce the
physical and chemical subtances of the waste.
Abstract: Statistics Canada stated that the wastewater treatment
facilities in most provinces are aging and passes 63% of their useful
life in 2007 the highest ratio among public infrastructure assets.
Currently, there is no standard condition rating system for wastewater
treatment plants that give a specific rating index that describe the
physical integrity of different infrastructure elements in the treatment
plant and its environmental performance. The main objective of this
study is to develop a condition-rating index for wastewater treatment
plants mainly activated sludge systems. The proposed WWTP CRI, is
based on dividing the treatment plant into its three treatment phases;
primary phase, secondary phase and the tertiary phase. The
condition-rating index will reflect the infrastructures state for each
phase, mainly tanks, pipes, blowers and pumps.
Abstract: Treatment of tar-containing wastewater is necessary
for the successful operation of biomass gasification plants (BGPs). In
the present study, tar-containing wastewater was treated using lime
and alum for the removal of in-organics, followed by adsorption on
powdered activated carbon (PAC) for the removal of organics. Limealum
experiments were performed in a jar apparatus and activated
carbon studies were performed in an orbital shaker. At optimum
concentrations, both lime and alum individually proved to be capable
of removing color, total suspended solids (TSS) and total dissolved
solids (TDS), but in both cases, pH adjustment had to be carried out
after treatment. The combination of lime and alum at the dose ratio
of 0.8:0.8 g/L was found to be optimum for the removal of inorganics.
The removal efficiency achieved at optimum
concentrations were 78.6, 62.0, 62.5 and 52.8% for color, alkalinity,
TSS and TDS, respectively. The major advantages of the lime-alum
combination were observed to be as follows: no requirement of pH
adjustment before and after treatment and good settleability of
sludge. Coagulation-precipitation followed by adsorption on PAC
resulted in 92.3% chemical oxygen demand (COD) removal and
100% phenol removal at equilibrium. Ammonia removal efficiency
was found to be 11.7% during coagulation-flocculation and 36.2%
during adsorption on PAC. Adsorption of organics on PAC in terms
of COD and phenol followed Freundlich isotherm with Kf = 0.55 &
18.47 mg/g and n = 1.01 & 1.45, respectively. This technology may
prove to be one of the fastest and most techno-economically feasible
methods for the treatment of tar-containing wastewater generated
from BGPs.
Abstract: The growing health hazardous impact of arsenic (As)
contamination in environment is the impetus of the present
investigation. Application of lactic acid bacteria (LAB) for the
removal of toxic and heavy metals from water has been reported.
This study was performed in order to isolate and characterize the Asresistant
LAB from mud and sludge samples for using as efficient As
uptaking probiotic. Isolation of As-resistant LAB colonies was
performed by spread plate technique using bromocresol purple
impregnated-MRS (BP-MRS) agar media provided with As @ 50
μg/ml. Isolated LAB were employed for probiotic characterization
process, acid and bile tolerance, lactic acid production, antibacterial
activity and antibiotic tolerance assays. After As-resistant and
removal characterizations, the LAB were identified using 16S rDNA
sequencing. A total of 103 isolates were identified as As-resistant
strains of LAB. The survival of 6 strains (As99-1, As100-2, As101-3,
As102-4, As105-7, and As112-9) was found after passing through the
sequential probiotic characterizations. Resistant pattern pronounced
hollow zones at As concentration >2000 μg/ml in As99-1, As100-2,
and As101-3 LAB strains, whereas it was found at ~1000 μg/ml in
rest 3 strains. Among 6 strains, the As uptake efficiency of As102-4
(0.006 μg/h/mg wet weight of cell) was higher (17 – 209%)
compared to remaining LAB. 16S rDNA sequencing data of 3 (As99-
1, As100-2, and As101-3) and 3 (As102-4, As105-7, and As112-9)
LAB strains clearly showed 97 to 99% (340 bp) homology to
Pediococcus dextrinicus and Pediococcus acidilactici, respectively.
Though, there was no correlation between the metal resistant and
removal efficiency of LAB examined but identified elevated As
removing LAB would probably be a potential As uptaking probiotic
agent. Since present experiment concerned with only As removal
from pure water, As removal and removal mechanism in natural
condition of intestinal milieu should be assessed in future studies.
Abstract: A shaft-type activated sludge reactor has been
developed in order to study the feasibility of high-rate wastewater
treatment. The reactor having volume of about 14.5 L was operated
with the acclimated mixed activated sludge under batch and
continuous mode using a synthetic wastewater as feed. The batch
study was performed with varying chemical oxygen demand (COD)
concentrations of 1000–3500 mg·L-1 for a batch period up to 9 h. The
kinetic coefficients: Ks, k, Y and kd were obtained as 2040.2 mg·L-1
and 0.105 h-1, 0.878 and 0.0025 h-1 respectively from Monod-s
approach. The continuous study showed a stable and steady state
operation for a hydraulic retention time (HRT) of 8 h and influent
COD of about 1000 mg·L-1. A maximum COD removal efficiency of
about 80% was attained at a COD loading rate and food-tomicroorganism
(F/M) ratio (COD basis) of 3.42 kg·m-3d-1 and 1.0
kg·kg-1d-1 respectively under a HRT of 8 h. The reactor was also
found to handle COD loading rate and F/M ratio of 10.8 kg·m-3d-1
and 2.20 kg·kg-1d-1 respectively showing a COD removal efficiency
of about 46%.
Abstract: Aluminum salt that is generally presents as a solid
phase in the water purification sludge (WPS) can be dissolved,
recovering a liquid phase, by adding strong acid to the sludge solution.
According to the reaction kinetics, when reactant is in the form of
small particles with a large specific surface area, or when the reaction
temperature is high, the quantity of dissolved aluminum salt or
reaction rate, respectively are high. Therefore, in this investigation,
water purification sludge (WPS) solution was treated with ultrasonic
waves to break down the sludge, and different acids (1 N HCl and 1 N
H2SO4) were used to acidify it. Acid dosages that yielded the solution
pH of less than two were used. The results thus obtained indicate that
the quantity of dissolved aluminum in H2SO4-acidified solution
exceeded that in HCl-acidified solution. Additionally, ultrasonic
treatment increased the rate of dissolution of aluminum and the
amount dissolved. The quantity of aluminum dissolved at 60℃ was 1.5
to 2.0 times higher than that at 25℃.
Abstract: The objective of this study was to investigate hydrogen production from alcohol wastewater by anaerobic sequencing batch reactor (ASBR) under thermophillic operation. The ASBR unit used in this study had a liquid holding volume of 4 L and was operated at 6 cycles per day. The seed sludge taken from an upflow anaerobic sludge blanket unit treating the same wastewater was boiled at 95 °C for 15 min before being fed to the ASBR unit. The ASBR system was operated at different COD loading rates at a thermophillic temperature (55 °C), and controlled pH of 5.5. When the system was operated under optimum conditions (providing maximum hydrogen production performance) at a feed COD of 60 000 mg/l, and a COD loading rate of 68 kg/m3 d, the produced gas contained 43 % H2 content in the produced gas. Moreover, the hydrogen yield and the specific hydrogen production rate (SHPR) were 130 ml H2/g COD removed and 2100 ml H2/l d, respectively.
Abstract: The present disposal routes of sewage sludge represent a critical environmental issue in Egypt. Recently, there has been an increasing concern about sewage sludge management due to the environmental risks, which resulted from the fast expansion of wastewater treatment plants without equal attention in dealing with the produced sludge. This paper discusses the current situation of sewage sludge management in Egypt presenting a brief overview of the existing wastewater treatment plants, sludge production and characteristics as well as options of beneficial use and potential demand of sewage sludge under Egyptian conditions. The characteristics of sewage sludge are discussed considering the results of own sampling and analysis as well as previous studies. Furthermore, alternative treatment scenarios for sewage sludge, which have been recently developed in Egypt, are discussed and perspectives for a sustainable agricultural use are outlined.
Abstract: The article presents test results on the changes
occurring in sewage sludge during the process of its storage. Tests
were conducted on mechanically dehydrated sewage sludge derived
from large municipal sewage treatment plants equipped with
biological sewage treatment systems. In testing presented in the paper
the focus was on the basic fuel properties of sewage sludge: moisture
content, heat of combustion, carbon share. In the first part of the
article the overview of the issues concerning the sewage sludge
management is presented and the genesis of tests is explained.
Further in the paper, selected results of conducted tests are discussed.
Changes in tested parameters were determined in the period of a 10-
month sewage storage.
Abstract: In the present study, an attempt was made to examine
the potential of aerobic mixed culture for decolourization of Remazol Black B dye in batch reactors. The effect of pH, temperature, inoculum, initial concentration of dye and initial concentration of
glucose was studied with an aim to determine the optimal conditions
required for maximum decolourization and degradation. The culture
exhibited maximum decolourization ability at pH between 7-8 and at
30°C. A 10% (v/v) inoculum and 1% (w/v) glucose concentration
were found to be the optimum for decolourization. A maximum of
98% decolourization was observed at 25 ppm initial concentration of
dye after 18 hours of incubation period. At higher dye concentration
of 300 ppm, the removal in colour was found to be 75% in 48 hours of incubation period. The results show that the enriched mixed culture from activated sludge has good potential in removal of Remazol Black B dye from wastewater under aerobic conditions.
Abstract: The direct sewage sludge application is a relative
cheap method for their liquidation. In the past heavy metal contents
increase in soils treated with sewage sludge was observed. In 2003
there was acceptance on act n.188/2003 about sewage sludge
application on soils. The basic philosophy of act is a safety of the
environmental proof of sludge application on soils. The samples of
soils from wastewater treatment plant (WTP) Poprad (35) and WTP
Michalovce (33 samples) were analyzed which were chosen for
sludge application on soils. According to the results only 14 areas for
Poprad and 25 areas for Michalovce are suitable for sludge
application according to act No. 188/2003. The application dose of
sludge was calculated 50 t.ha-1 or 75 t. ha-1 once in 5 years to ensure
that heavy metal contents in treated soils will be kept.
Abstract: Anaerobic digestion process is one of the alternative
methods to convert organic waste into methane gas which is a fuel
and energy source. Activities of various kinds of microorganisms are
the main factor for anaerobic digestion which produces methane gas.
Therefore, in this study a modified Anaerobic Baffled Reactor (ABR)
with working volume of 50 liters was designed to identify the
microorganisms through biogas production. The mixture of 75%
kitchen waste and 25% sewage sludge was used as substrate.
Observations on microorganisms in the ABR showed that there exists
a small amount of protozoa (5%) and fungi (2%) in the system, but
almost 93% of the microorganism population consists of bacteria. It
is definitely clear that bacteria are responsible for anaerobic
biodegradation of kitchen waste. Results show that in the
acidification zone of the ABR (front compartments of reactor) fast
growing bacteria capable of growth at high substrate levels and
reduced pH was dominant. A shift to slower growing scavenging
bacteria that grow better at higher pH was occurring towards the end
of the reactor. Due to the ability of activity in acetate environment the
percentages of Methanococcus, Methanosarcina and Methanotrix
were higher than other kinds of methane former in the system.
Abstract: The use of sewage sludge and effluents from
wastewater treatment plants for irrigation of agricultural lands is on
the rise particularly in peri-urban areas of developing countries.
The reuse of nutrients and organic matter in treated wastewater
and sewage sludge via land application is a desirable goal. However,
trace or heavy metals present in sludge pose the risk of human or
phytotoxicity from land application. Long-term use of sewage
sludge, heavy metals can accumulate to phytotoxic levels and results
in reduced plants growth and/or enhanced metal concentrations in
plants, which consumed by animals then enter the food chain. In this
research, the amount of heavy metals was measured in plants
irrigated with wastewater and sludge application. For this purpose,
three pilots were made in a Shush treatment plant in south of Tehran.
Three plants species, spinach, lettuce and radish were selected and
planted in the pilots.First pilot was irrigated just with wastewater of
treatment plant and second pilot was irrigated with wastewater and
sludge application .Third pilot was irrigated with simulated heavy
metals solution equal 50 years of irrigation. The results indicate that
the average of amount of heavy metals Pb, Cd in three plant species
in first pilot were lower than permissible limits .In second pilot,
Cadmium accumulations are high in three species plants and more
than the standard limits. Concentration of Cd , Pb have exceed their
permitted limits in plants in third pilot . It was concluded that the use
of wastewater and sludge application in agricultural lands enriched
soils with heavy metals to concentrations that may pose potential
environmental and health risks in the long-term.