Evaluation of Microbial Contamination of Groundwater under Different Topographic Conditions and Household Water Treatment Systems in Special Region of Yogyakarta Province, Indonesia

Since the coverage of piped water is still only 20.1% in Indonesia, many people rely on groundwater for drinking and daily use, although the quality of the groundwater is not well understood. This study evaluated the influence of the topography, well type, groundwater abstraction depth, sanitation facility type, and distance between the well and the sanitation facility on the groundwater quality. In addition, a possible household treatment system was investigated based on microbial removal efficiency and household acceptance. The results showed the groundwater abstraction depth and well type were the most important factors in controlling microbial contamination. The sanitation facility type, except small-scale sewer systems, and the distance from a well were not significantly correlated with E. coli concentration. A high microbial concentration was found in a flat area with predominantly shallow wells, latrines, and septic tanks because the topographic conditions determined the commonly used well types and groundwater abstraction depth. The RO + UV system was the only system that assured microbial safety of treated water. The chlorination and microfiltration systems had difficulty with chlorine-dosage adjustment and microbial removal, respectively. Raising public awareness of water quality problems was found to be important to improve acceptance of household treatment systems.

Microbial Removal of Pb(II) Using an Upflow Anaerobic Sludge Blanket (UASB) Reactor

The main objective of this study was to achieve the continuous biorecovery and bioreduction of Pb(II) using an industrially obtained consortia as a biocatalyst. An upflow anaerobic sludge blanket reactor was used in the treatment process. The bioremediation technique that was applied made use of a yeast extract as the microbial substrate and Pb(NO3)2 as the source of Pb(II). The UASB reactor exhibited removal efficiencies of between 90 and 100% for the inlet Pb concentrations from 80 to 2000 ppm and a maximum removal rate of 1948.4 mg/(L·d) was measured. XRD and XPS analyses of the precipitate revealed the presence of Pb0, PbO, PbS and PbSO4. Supporting experimental work carried out included growth measurements, pH, oxidation–reduction potentials and nitrate levels.

Microbial removal rate efficiencies measured for coral sand

<p>Coral sand forms the surficial geology on many coral cay and low-lying atolls, such as are located throughout the Pacific region. Shallow groundwater hosted within such sand is the main source of freshwater for many island communities. It is critically at risk from the impacts of climate-change and anthropogenic stresses. A United Nations' Sustainable Development Goal is to improve water access and sanitation issues in such environs. Working towards that goal, we have conducted a set of laboratory column experiments to obtain some initial measures of microbial removal efficiencies for coral sand substrate from the Pacific atoll of South Tarawa, Kiribati.  </p><p>In one experiment we attempted to mimic physio-chemical conditions at the Bonriki Freshwater Reserve that supplies most of the water on South Tarawa. Three small plastic columns were packed with very poorly sorted gravelly coral sand sampled from the reserve. The effective transport of Escherichia coli J6-2 and MS2 bacteriophage through the packed columns was evaluated under saturated flow conditions.</p><p>In a second experiment we conducted infiltration tests on naturally well-sorted coral sand, sourced from Bikenibeu beach, South Tarawa. We perceive such sand has potential to be used in the construction of effluent drainage fields from septic tank systems in use on South Tarawa, where currently there are no established design criteria. The sand was packed to a depth of 400 mm in triplicate glass column apparatus. It was conditioned by dosing with septic tank effluent twice per day for 27 days (8 mm head each event). Effluent spiked with bacterial and viral indicator organisms: Escherichia coli J6-2, Enterococci faecalis and MS2 bacteriophage, as well as the viral pathogens: adenovirus, echovirus, norovirus and rotavirus was then dripped on to the columns, as a 35 mm application. Any resulting drainage from the base of the columns was collected and analysed, and the depth profile of the tracer organisms was examined in the sand columns by destructive sampling.</p><p>The very poorly sorted coral substrate from Bonriki Reserve proved very effective at attenuating Escherichia coli J6-2 under saturated flow conditions. We estimated a spatial removal rate of 0.05 ± 0.02 log<sub>10</sub> cm<sup>-1</sup> for this bacterial tracer. No removal rate could be quantified for the viral indicator. Although overall, our observations suggest the coral sand was significantly less effective at attenuating MS2 bacteriophage than it was at attenuating Escherichia coli J6-2.</p><p>In the unsaturated column experiments made on beach sand conditioned with effluent, all the microorganisms examined demonstrated >4-log removal values. Contrary to our finding from the saturated sand column experiment made with material from Bonriki Reserve, the conditioned coral beach sand filters demonstrated higher affinity for MS2 bacteriophage (also viruses) than they did Escherichia coli J6-2, or Enterococci faecalis.</p>

Copper removal from semiconductor CMP wastewater in the presence of nano-SiO2 through biosorption

Copper-bearing wastewater from chemical mechanical planarization (CMP) is a typical semiconductor development byproduct. How to effectively treat Cu2+ in the CMP wastewater is a great concern in the microchip manufacturing industry. In this study, we investigated the potential for the microbial removal of Cu2+ by a multiple heavy metal-resistant bacterium Cupriavidus gilardii CR3. The environmental factors, including pH, nano-SiO2, ionic strengths, and initial concentrations of Cu2+, and adsorption times on the bioremoval of Cu2+ in CMP wastewater were optimized. Under optimal condition, the maximum biosorption capacity for Cu2+ was 18.25 mg g−1 and the bioremoval rate was 95.2%. The Freundlich model is described well for the biosorption of Cu2+ in CMP wastewater in the presence of nano-SiO2 (R2 = 0.99). The biosorption process obeyed the pseudo-second-order kinetic equation (R2 > 0.99). In the column experiment, the advection–dispersion–retention model fitted the breakthrough curve of all experiments well (R2 > 0.95). The attachment coefficient in the sand matrix coated by CR3 biofilm was 2.24–2.80 times as that in clean sand. Overall, C. gilardii CR3 is a promising candidate to remove Cu2+ from CMP wastewater. Nano-SiO2 in CMP wastewater did not inhibit the bioremoval of Cu2+ but showed a slight promotion effect instead.