Evaluation of the Efficiency of Ceramic Water Filter Improved by Dried Duckweed Plant (Lemna minor) in Wastewater Treatment

The lack of clean water sources due to pollution and industrialisation is a major problem in many countries including Nigeria. To overcome this challenge, various methods have been adopted including phytoremediation treatment. This study evaluates dried duckweed an aquatic plant and its removal efficiency in comparison with other locally available treatment materials. This was achieved by formulating ceramic water filters (C.W.F) categorized into four different types- clay and kaolin(P1), clay, kaolin and sawdust(P2), clay, kaolin and charcoal(P3) and clay, kaolin and duckweed(P4). These filters were subjected to contaminated water and the following physicochemical parameters Colour, pH, Conductivity(Ec), Fluoride(F-), Magnesium(Mg2+), Nitrites(NO2-), Sulphates (SO42-), Ammonia (NH3) and Total Suspended Solids (TSS) and Total Nitrogen were determined before and after filtration. In all the ceramic water filters, the filter improved by duckweed showed the best removal efficiency of Colour – 100%, Conductivity(Ec) -72.60%, Fluoride(F)- 99.82%, Magnesium(Mg2+)- 51.68% Nitrites(NO2-)-92.34, Sulphates (SO42-)- 46.09%, Ammonia (NH3)-98.75%, and Total Suspended Solids (TSS)- 85.43% and Total Nitrogen (TN) -83.79% indicating that duckweed is capable of adsorbing inorganic and organic pollutants from water.

Plasticity characterization of certain Nigeria clay minerals for their application in ceramic water filters

Plasticity is an essential property of clay that determines its suitability for water filtration. There are no published works on the plastic behavior of clays from the study locations. The plastic behavior of seven Nigerian clays was examined using plasticity indices and compressive stress parameters in relation to chemical compositions and moisture content. The objective is to determine plastic behavior of some Nigerian clays and their suitability in production of Expanded Clay Aggregates (ECA) for water filters. Compressive stresses and deformation parameters were determined experimentally and compared theoretically. Atterberg limits (D 4318) were used to determine the plasticity indices. Chemical compositions of the samples were examined with XRF and correlated with plasticity and mineral contents of the clays. The clays are aluminosilicates with SiO2/Al2O3 ratio of 1.61 to 3.03 and plastic indices of 8 to 49. Low plastic indices (8–11) and low compressive stresses parameters were observed for kaolinite clays (0.002 MPa) due to their low affinity for water while zeolite rich clays showed high plastic indices (46 and 49) for Obowo and Minna and sharp difference in their compressive stresses parameters (0.15 and 0.03 MPa) at optimum moisture contents of 57% and 53%, respectively. Despite varying moisture content, chemical and mineral compositions, all curves showed similar trends apart from kaolinites at 40% moisture content. Relationships exist among microstructural properties, chemical composition, moisture content, compressive strength, and plasticity indices of the clays. The plastic behaviors show they are suitable for development of ECA for water filters.

Field Investigation and Economic Benefit of a Novel Method of Silver Application to Ceramic Water Filters for Point-Of-Use Water Treatment in Low-Income Settings

In this study, we report on field testing of ceramic water filters (CWFs) fabricated using a new method of silver application (using silver nitrate as a raw material) compared to conventionally manufactured CWFs (fabricated with silver nanoparticles). Both types of filters were manufactured at the PureMadi ceramic filter production facility in Dertig, South Africa. Thirty households received filters fabricated with silver nitrate (AgNO3), and ten of those households were given an extra filter fabricated with silver nanoparticles. Filter performance was quantified by measurement of total coliform and Escherichia coli (E. coli) removal and silver residual concentration in the effluent. Silver-nitrate CWFs had removal efficiencies for total coliforms and E. coli of 95% and 99%, respectively. A comparison of the performance of silver-nitrate and silver-nanoparticle filters showed that the different filters had similar levels of total coliform and E. coli removal, although the silver nitrate filters produced the highest average removal of 97% while silver nanoparticles filters recorded an average removal of 85%. Average effluent silver levels were below 10 ppb for the silver-nitrate and silver-nanoparticle filters, which was significantly below the Environmental Protection Agencies of the United States (EPA) and World Health Organization (WHO) secondary guidelines of 100 ppb. Silver-nitrate filters resulted in the lowest effluent silver concentrations, which could potentially increase the effective life span of the filter. A cost analysis shows that it is more economical to produce CWFs using silver nitrate due to a reduction in raw-material costs and reduced labor costs for production. Furthermore, the production of silver-nitrate filters reduces inhalation exposure of silver by workers. The results obtained from this study will be applied to improve the ceramic filtration technology as a point-of-use (POU) water treatment device and hence reduce health problems associated with microbial contamination of water stored at the household level.