जल विज्ञान: वर्तमान अनुसंधान

Composite nanofiltration (NF) membrane was developed polyacrylic acid (PAA) in situ UV graft polymerization process using ultrafiltration polysulfone (PSf) membrane as porous support. Through the observation using SEM, the PSf UF membranes fabricated by phase inversion method, demonstrated numerous finger-like pores. AFM microscopy showed the roughness of surface was reduced by increase of UV irradiation times. The feasibility of membrane processes for treating simulated mixture by varying the feed pressures (1–4 bars), feed pH and UV irradiation times studied to assess the separation performance of NF membranes. The rejections of sodium chloride and sodium sulfate were moderate and declined with the increase of concentration. Color removal by NF with a high rejection of 99.90% was achieved. It was found that the efficiency of NF membranes used in the treatment of colored water effluents was greatly affected by the presence of salts and dyes in the mixture and the retention of dyes decreased with the salt concentration due to a decrease of the Donnan effect.

This paper reports experimental assays on the utilisation of the ozone technology to disinfect backyard swimming pool waters. Tests were carried out utilizing a semi-batch reactor in which various samples containing 103 CFU/mL of E. coli, E. hirae, S. aureus and P. aeruginosa were treated considering different dissolved ozone doses. Results show a low disinfection activity at ozone concentration of 0, 05 mgO3/L, a potential to disinfect water in 5-15 seconds at concentration around 0, 10 mgO3/L and a drastic abatement of the disinfection capabilities under the concentration of 0, 01 mgO3/L. Some ozone purging and microorganisms revitalization trials were carried out too.

Growth, crop yields and nutrient uptake of Okra [Abelmoschus esculentus (L.) Moench] irrigated with different mix proportions of stream water to partially treated sewage effluent (0:100; 25:75; 50:50; 75:25; 100:0) under furrow system were determined. There were four replicates of each treatment and the 100% stream water served as the control, the stream water has little effluent discharges along the downstream. The 75% treated sewage effluent gave the highest fruit yield of 10.5 t/ha while the 100% stream water gave the lowest fruit yield of 5.40 t/ha. The highest dry matter yield of 9.8 t/ha was obtained with 100% partially treated sewage. There was no significant difference among the treatments in the number of leaves and plant heights. The 100% partially treated sewage effluent however gave significantly (P<0.05) higher leave area index and plant girth than other treatments while the 50% partially treated sewage had significantly (P<0.05) higher fruit moisture content at harvest. Analysis of the plant indicated that maximum nutrient uptake occurred in 25:75% stream water: sewage effluent treatment and the nutrient content of the crop in all the treatments compared with acceptable limits in common crops. There was little or no trace of odour on the water or trace of bacteria in the harvested crop since the water has been treated through waste water stabilization ponds. The sewage resulted in higher P, K, and Cu content of the soil. This study shows that okra can safely be grown in the study area with partially treated sewage effluent but would be best when mixed in 25:75% of stream water to partially treated sewage and the soil leached intermittent to prevent Cu and macro-nutrient build-up.