Nepal Journal of Environmental Science

Biosurfactants from renewable sources - A review

2022-09-20T23:38:56+00:00

Biosurfactants have wide applications in pharmaceutical, agriculture and food industries. The research area of biosurfactants is gaining immense attention. The review mentions here the advantages and various substrates used for biosurfactants production. The pre-treatment of substrates for biosurfactants production is also focused. The production of biosurfactants by solid state fermentation is also described. The renewable substrates, yield and microorganisms used for biosurfactant production are also taken into consideration. The screening methods for biosurfactant are also described. The use of renewable sources for biosurfactant production is specially focused in the review. This will be very eco-friendly, easy and economical. More studies need to BE done on large-scale production of biosurfactants using genetically engineered microorganisms.

Physical and chemical analysis of Beirut ammonium nitrate blast: A concern of particulate matter in atmosphere

2022-02-26T15:44:51+00:00

Chemical disasters are caused by improper management, handling, transportation, and sudden accidents. The massive explosion of ammonium nitrate silo in the port of Beirut on August 4, 2020, has threatened the world with the loss of 220 people, about 6500 injuries, huge property loss, and environmental contamination. This paper aims to summarize the major ammonium nitrate accidents in the past 100 years in the world. We analyzed the accidents in terms of frequency, causes, property loss, and deaths. We reported 43 accidents in which 7 accidents triggered more than 100 casualties. Altogether seven terrorist attacks with ammonium nitrate are reported leading to the death of 411 people and huge loss of assets. The explosion releases a large amount of energy and produces a variety of gases along with nitrogen oxides, ammonia, and a lot of particulate matter (PM), which significantly contributes to air pollution. The size and amount of PM imposes negative impact on environment like low visibility, decreased solar radiation and adverse health impacts like chronic respiratory, pulmonary, cardiovascular, and other human diseases. Proper management and safety measures with stringent regulations at national and international level is warranted for the safe and sustainable use of industrial chemicals.

Evaluation of multiple water quality indices for irrigation purposes for the Bheri and Babai River systems, Nepal

2022-08-28T12:00:07+00:00

The main purpose of this study was to assess the irrigation water quality of the Bheri and Babai Rivers and their tributaries prior to the proposed inter-basin water transfer (IBWT) in western Nepal. A total of 40 water samples from five sites in each river system were collected from January (winter), March-April (spring), June (summer) and October (autumn) in 2018; and some important irrigation water quality parameters were assessed. All the assessed parameters viz. pH, Total Dissolved Solids (TDS), Total Hardness (TH), permeability index (PI), percent sodium (%Na), sodium adsorption ratio (SAR), magnesium hazard (MAR), residual sodium carbonate (RSC), Kelly’s index (KI) from all sites were observed suitable for irrigation. USSL diagram showed that water from both the rivers belongs to the S1-C2 category indicating good for irrigation purposes. The Wilcox diagram revealed that all samples fall into the excellent to a good class. Based on Irrigation Water Quality Index (IWQI), 3 sampling sites fall in the high restriction category and 7 sampling sites fall in the moderate restriction category, indicating anthropogenic impacts on irrigation water quality at some sites.

Evaluation of benthic macroinvertebrate communities in upstream and downstream of Kulekhani Multipurpose Reservoir, Makawanpur, Nepal

2021-06-29T05:33:49+00:00

Reservoir construction in the natural waterways can disrupt the structure and function of riparian ecosystems with the alteration in abundance and composition of aquatic organisms. This study assessed the variation in Benthic Macroinvertebrates (BMIs) communities in upstream (Chitlang and Seti Streams) and downstream (spillway) of Kulekhani multipurpose reservoir, Makawanpur, Nepal. Multi-habitat qualitative samplings with Ganga River System Biotic Score (GRSBIOS) index was used for the biological water quality assessment. Out of total 25 families and 8 orders of identified BMIs, Diptera and Coleoptera order are abundant whereas Oligochaeta and Odonata order are lowest. Taxa richness and abundance of BMIs were estimated to be higher upstream. Number of EPT taxa (6 to 2) and percentage of EPT (35.07 to 28.04 %) abundance were recorded in decreasing order of response toward downstream. The upstream showed a high Shannon and Simpson’s diversity index. Chitlang Stream is found slightly polluted as Average Score Per Taxa (ASPT) score is calculated as 6.1 (River Water Quality Status (RWQS)-I)). Similarly, immediate downstream is critically polluted with RWQS-III whereas Seti Stream and spillway after 4 km were found to be moderately polluted as RWQS-II. Canonical Correspondence Analysis (CCA) showed that pH, temperature, and dissolved oxygen have a high influence in BMIs assemblages. The study depicts the ecological health of the stream immediately downstream of the reservoir is disturbed with presence of tolerant BMIs assemblages. The implication of the study can be in the assessment of impact caused by the reservoir in the ecological status of the water transfer.

Ichthyofaunal diversity in the lower Narayani River, Chitwan, Nepal

2022-01-06T08:19:27+00:00

Narayani River in Nepal is an excellent habitat for diverse groups of aquatic organisms. A stretch of 70 km of lower Narayani River was studied for fish diversity and composition. A total species richness of 40 representing 14 families and 7 orders was reported. Order cypriniformes had high taxa dominance of 67% whereas least taxa richness of only 2 % with single species were recorded from orders Beloniformes, Clupeiforms, Gobiiformes and Osteoglossiformes. Simpson diversity index ranged from 0.1 to 0.8 whereas Shannon diversity and Pielou’s evenness ranged from 0.2 to 2.1 and 0.3 to 0.8, respectively. Minimum taxa richness and abundance were recorded in river stretches with industrial effluents situated along the bank of the river. High conservation species such as Wallago attu, Chitala chitala, Tor tor and Neolissochilus hexagonolepis were documented in the most downstream section, i.e., Tribeni of the river. Non-metric multidimensional scaling (NMDS) analysis distinguished three clusters of sites for the river where fish community composition was found to be significantly different (p <0.05). The outcomes of the study help identifying critical river stretches that need high conservation efforts for conserving fish diversity in the lower Narayani River.

Photocatalytic decomposition of textile dyeing effluents using TiO2, ZnO, and Fe2O3 catalysts

2022-07-13T16:18:13+00:00

Textile dyeing industries are facing the challenge of environmental sustainability due to the discharge of large volumes of textile dyeing effluents containing residual reactive dyes and chemicals. Hence, it is imperative to treat the discharged effluents before releasing them into the environment. The study aimed to degrade textile dyeing effluent using some selected catalysts. The study collected some effluent samples from the Bangladesh Small and Cottage Industries Corporation (BICIC) of Rajshahi, and were subjected to photocatalytic decomposition using three catalysts such as TiO₂, ZnO, and Fe₂O₃. It considered several operational parameters, including irradiation time, catalyst concentration, pH, and dose of the oxidizing agent for optimizing the color removal efficiency. Besides, the kinetics and the mineralization of the photocatalytic decomposition reactions were examined. The study results showed that the maximum 81.6% decomposition was achieved using ZnO catalyst at the optimized conditions. It also showed that TOC and COD were reduced by about 97.9% and 43.53%, respectively. Kinetics study of the degradation process of the effluents showed pseudo-first-order reactions indicating the potentiality of the catalysts. The study observed that the ZnO is suitable for photocatalytic degradation in the textile dye effluents treatment.