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Vehicle and industrial emissions are responsible for a considerable share of urban air pollution concentrations. We conducted a comparative study in Dalian, China and Faisalabad, Pakistan to reevaluate NO₂, SO₂, and CO concentrations. Our study was conducted over the course of one year at different stations in both cities, and measured values were compared with ambient air quality standards such as NEQS-Pakistan, NAAQSUSEPA, CNAAQS-China, and global standard WHO. The NO₂ concentrations in Faisalabad varied from 185- 262 μg/m³ , whereas it was in the range of 44-133 μg/m³ in Dalian. The SO₂ concentration was found in the range of 66-190 μg/m³ and 56-128 μg/m³ , while CO varied from 5.4-22.3 mg/m³ and 0.3-2.8 mg/m³ , respectively, in Faisalabad and Dalian. The annual average NO₂, SO₂, and CO concentrations were below the permissible limits in Dalian; however, the measured values were considerably higher in Faisalabad. Our results are the first to compare air quality of two countries at different stations and highlight the possibility of reducing air pollution by comparing conditions.
In developing countries, good-quality water is contaminated due to the disposal of untreated municipal and industrial wastewater (WW) into natural water reservoirs. Most of the wastewater is not treated properly according to international standards, and usually is disposed of and/or utilized for irrigation without appropriate treatment. The main hurdles in providing wastewater treatment (WWT) in developing countries include high costs, and the poor design, installation, and operation of conventional WWT systems. Therefore, the present study explores the maize cobs trickling filter-based (MCTF) low-cost WWT option for developing countries like Pakistan, India, and Bangladesh. In this regard, indigenous media trickling filter was designed and developed using maize cobs as packing material for biofilm growth. The MCTFWWT system was continually operated and monitored for six months at constant hydraulic wastewater loading of about 113±2 m3 per m2 per day. The experimental data covers winter and summer seasons with temperature variations from 23ºC to 43ºC. System performance was evaluated by means of various WWT parameters, including biological and chemical oxygen demands (BOD5 and COD), total suspended and dissolved solids (TSS and TDS), turbidity, and color – before and after WWT. Experimental results showed that the MCTF-WWT system successfully removed about 79% BOD and 75% COD on average. The key reason for effective BOD and COD removal was rapid development of microbial film (within the first two weeks). Furthermore, the MCTF-WWT system removed 42-46% TSS, 28-30% TDS, 43-46% turbidity, and 33-37% color. The study concludes that the MCTF-WWT system is an effective and economical WWT option for irrigation/agricultural applications in developing countries.
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