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: 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 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: In this study, communities of ammonia-oxidizing
archaea (AOA) and ammonia-oxidizing bacteria (AOB) in nitrifying
activated sludge (NAS) prepared by enriching sludge from a
municipal wastewater treatment plant in three continuous-flow
reactors receiving an inorganic medium containing different
ammonium concentrations of 2, 10, and 30 mM NH4
+-N (NAS2,
NAS10, and NAS30, respectively) were investigated using molecular
analysis. Results suggested that almost all AOA clones from NAS2,
NAS10, and NAS30 fell into the same AOA cluster and AOA
communities in NAS2 and NAS10 were more diverse than those of
NAS30. In contrast to AOA, AOB communities obviously shifted
from the seed sludge to enriched NASs and in each enriched NAS,
communities of AOB varied particularly. The seed sludge contained
members of N. communis cluster and N. oligotropha cluster. After it
was enriched under various ammonium loads, members of N.
communis cluster disappeared from all enriched NASs. AOB with
high affinity to ammonia presented in NAS 2, AOB with low affinity
to ammonia presented in NAS 30, and both types of AOB survived in
NAS 10. These demonstrated that ammonium load significantly
influenced AOB communities, but not AOA communities in enriched
NASs.
Abstract: This paper describes technological possibilities to
enhance methane productionin the anaerobic stabilization of wastewater treatment plant excess sludge. This objective can be achieved by the addition of waste residues: crude glycerol from biodiesel production and residues from fishery. The addition
ofglycerol in an amount by weight of 2 – 5% causes enhancement of methane production of about 250 – 400%. At the same time the
percentage increase of total solids concentration in the outgoing sludge is ten or more times less. The containment of methane in
biogas is higher in case of admixed substrate.
Abstract: One of the main challenges for one phase anaerobic digestion processes is the high concentration of NH4+ and PO4 3- ions
in the digested sludge supernatant. This project focuses on enhancing the removal of nutrients during the anaerobic digestion process through fixing both NH4+ and PO4 3- ions in the form of struvite (magnesium ammonium phosphate, MAP, MgNH4PO4.6H2O) within the anaerobic sludge. Batch anaerobic digestion tests showed that Mg2+ concentration in the range 279 – 812 mg/L had insignificant effect on CGP but incurred a slight increase in COD removal. The reactor that had soluble Mg2+:NH4+:PO43- at a molar ratio of 1.28:1:00:1:00 achieved the best performance enhancement of 8% increase in COD removal and 32% reduction in NH4+ in the reactor supernatant. Overall, the results show that there is a potential to optimise conventional anaerobic digestion such that supernatant lean in P and N, and sludge rich in nutrients are obtained.
Abstract: The aim of this study was to investigate the
effectiveness of anaerobic digestion for the treatment of wool
scouring wastes. The experiments design comprised three ratios of
waste (W) to seed(S) (W:S) of 25:75, 50:50 and 75:25, corresponding
to 1.9. 1.7 and 1.5g tCOD/g TS, respectively, with or without
chemicals addition. NH4Cl was added to the reactors as a source for
nitrogen to achieve C:N:P of 420:14:3. A cationic flocculent was
added at 0.5 and 0.75% to enhance flocculation of sludge. The results
showed that the reactors that received W:S at a ratio of 25:75
produced the largest volume of biogas. The final soluble COD
(sCOD) was below the limits for discharge to the sewer system.
Abstract: Brick is one of the most common masonry units used as building material. Due to the demand, different types of waste have been investigated to be incorporated into the bricks. Many types of sludge have been incorporated in fired clay brick for example marble sludge, stone sludge, water sludge, sewage sludge, and ceramic sludge. The utilization of these waste materials in fired clay bricks usually has positive effects on the properties such as lightweight bricks with improved shrinkage, porosity, and strength. This paper reviews on utilization of different types of sludge wastes into fired clay bricks. Previous investigations have demonstrated positive effects on the physical and mechanical properties as well as less impact towards the environment. Thus, the utilizations of sludge waste could produce a good quality of brick and could be one of alternative disposal methods for the sludge wastes.
Abstract: Intermittent aeration process can be easily applied on
the existing activated sludge system and is highly reliable against the loading changes. It can be operated in a relatively simple way as well.
Since the moving-bed biofilm reactor method processes pollutants by attaching and securing the microorganisms on the media, the process
efficiency can be higher compared to the suspended growth biological
treatment process, and can reduce the return of sludge. In this study,
the existing intermittent aeration process with alternating flow being
applied on the oxidation ditch is applied on the continuous flow stirred tank reactor with advantages from both processes, and we would like
to develop the process to significantly reduce the return of sludge in the clarifier and to secure the reliable quality of treated water by
adding the moving media. Corresponding process has the appropriate
form as an infrastructure based on u- environment in future u- City and
is expected to accelerate the implementation of u-Eco city in conjunction with city based services. The system being conducted in a
laboratory scale has been operated in HRT 8hours except for the final
clarifier and showed the removal efficiency of 97.7 %, 73.1 % and 9.4
% in organic matters, TN and TP, respectively with operating range of
4hour cycle on system SRT 10days. After adding the media, the removal efficiency of phosphorus showed a similar level compared to
that before the addition, but the removal efficiency of nitrogen was
improved by 7~10 %. In addition, the solids which were maintained in
MLSS 1200~1400 at 25 % of media packing were attached all onto the
media, which produced no sludge entering the clarifier. Therefore, the
return of sludge is not needed any longer.
Abstract: A novel sponge submerged membrane bioreactor
(SSMBR) was developed to effectively remove organics and
nutrients from wastewater. Sponge is introduced within the SSMBR
as a medium for the attached growth of biomass. This paper evaluates
the effects of new and acclimatized sponges for dissolved organic
carbon (DOC) removal from wastewater at different mixed liquor
suspended solids- (MLSS) concentration of the sludge. It was
observed in a series of experimental studies that the acclimatized
sponge performed better than the new sponge whilst the optimum
DOC removal could be achieved at 10g/L of MLSS with the
acclimatized sponge. Moreover, the paper analyses the relationships
between the MLSSsponge/MLSSsludge and the DOC removal efficiency
of SSMBR. The results showed a non-linear relationship between the
biomass parameters of the sponge and the sludge, and the DOC
removal efficiency of SSMBR. A second-order polynomial function
could reasonably represent these relationships.
Abstract: The objective of this study is to evaluate the
occurrence of fungi in aerobic and anoxic activated sludge from
membrane bioreactors (MBRs). Thirty-six samples of both aerobic
and anoxic activated sludge were taken from 2 MBR treating
domestic wastewater. Over a period of eight months 2 samples from
each plant were taken per month. The samples were prepared for
count and definition of fungi. The obtained data show that, sixty
species belonging to 27 genera were collected from activated sludge
samples under aerobic and anoxic conditions. Regarding to the fungi
definition, under aerobic condition the Geotrichum was found at
(8.8%) followed by Penicillium (75.0%), Yeasts (65.7%) and
Trichoderma (55.5%), while Yeasts (77.1%) Geotrichum
candidumand Penicillium (61.1%) species were the most prevalent in
anoxic activated sludge. The results indicate that activated sludge is
habitat for growth and sporulation of different groups of fungi, both
saprophytic and pathogenic.
Abstract: The volume of biosolids produced in Malaysia
nowadays had increased proportionally to its population size. The end
products from the waste treatments were mounting, thus inevitable
that in the end the environment will be surrounded by the waste. This
study was conducted to investigate the suitability of biosolids to be
reused as fertilizer for non-food crop. By varying the concentration of
biosolids applied onto the soil, growth of five ornamental plant
samples were tested for eight consecutive weeks. The results show
that the pH of the soil after the addition of biosolids ranges from 6.45
to 6.56 which is suitable for the plant growth. The soil samples that
contains biosolid also show higher amount of macronutrients (N, P,
K) and the heavy metals content are significantly increased in the
plant however it does not exceed the guidelines drawn by the
Environmental Protection Agency. It is also proven that there was
only small significant different in the performance of plant growth
between biosolids and commercial fertilizer. It can be seen that
biosolids was able to perform just as well as commercial fertilizer.
Abstract: A high performance clarification system has been
discussed for advanced aqueous reprocessing of FBR spent fuel.
Dissolver residue gives the cause of troubles on the plant operation of
reprocessing. In this study, the new clarification system based on the
hybrid of centrifuge and filtration was proposed to get the high
separation ability of the component of whole insoluble sludge. The
clarification tests of simulated solid species were carried out to
evaluate the clarification performance using small-scale test apparatus
of centrifuge and filter unit. The density effect of solid species on the
collection efficiency was mainly evaluated in the centrifugal
clarification test. In the filtration test using ceramic filter with pore
size of 0.2μm, on the other hand, permeability and filtration rate
were evaluated in addition to the filtration efficiency. As results, it was
evaluated that the collection efficiency of solid species on the new
clarification system was estimated as nearly 100%. In conclusion, the
high clarification performance of dissolver liquor can be achieved by
the hybrid of the centrifuge and filtration system.