Abstract: Concrete performance is strongly affected by the
particle packing degree since it determines the distribution of the
cementitious component and the interaction of mineral particles. By
using packing theory designers will be able to select optimal
aggregate materials for preparing concrete with low cement content,
which is beneficial from the point of cost. Optimum particle packing
implies minimizing porosity and thereby reducing the amount of
cement paste needed to fill the voids between the aggregate particles,
taking also the rheology of the concrete into consideration. For
reaching good fluidity superplasticizers are required. The results from
pilot tests at Luleå University of Technology (LTU) show various
forms of the proposed theoretical models, and the empirical approach
taken in the study seems to provide a safer basis for developing new,
improved packing models.
Abstract: In India, the quarrel between the budding human
populace and the planet-s unchanging supply of freshwater and
falling water tables has strained attention the reuse of gray water as
an alternative water resource in rural development. This paper
present the finest design of laboratory scale gray water treatment
plant, which is a combination of natural and physical operations such
as primary settling with cascaded water flow, aeration, agitation and
filtration, hence called as hybrid treatment process. The economical
performance of the plant for treatment of bathrooms, basins and
laundries gray water showed in terms of deduction competency of
water pollutants such as COD (83%), TDS (70%), TSS (83%), total
hardness (50%), oil and grease (97%), anions (46%) and cations
(49%). Hence, this technology could be a good alternative to treat
gray water in residential rural area.
Abstract: This study presents the performance of membrane
bioreactor in treating high phosphate wastewater. The laboratory
scale MBR was operated at permeate flux of 25 L/m2.h with a hollow
fiber membrane (polypropylene, approx. pore size 0.01 - 0.2 μm) at
hydraulic retention time (HRT) of 12 hrs. Scanning electron
microscopy (SEM) and energy diffusive X-ray (EDX) analyzer were
used to characterize the membrane foulants. Results showed that the
removal efficiencies of COD, TSS, NH3-N and PO4
3- were 93, 98, 80
and 30% respectively. On average 91% of influent soluble microbial
products (SMP) were eliminated, with the eliminations of
polysaccharides mostly above 80%. The main fouling resistance was
cake resistance. It should be noted that SMP were found in major
portions of mixed liquor that played a relatively significant role in
membrane fouling. SEM and EDX analyses indicated that the
foulants covering the membrane surfaces comprises not only organic
substances but also inorganic elements including Mg, Ca, Al, K and
P.