Muhammad Shafiq

The global population increase has been exerting unprecedented pressures on the provision of safer surface and groundwater for food crop production. Particularly, intensifying mixing of untreated i...

The socio-economic constraints-driven under provision of scientifically designed landfills for effective management of hazardous industrial wastes like tannery solid waste (TSW) in the developing countries. Disposal of TSW at designated and non-designated open dumps (OD) renders seasonal leachate runoff into adjacent agricultural fields when intense precipitation hits mountainously stacked TSWOD during summer and winter monsoon. However, TSWOD driven impacts on soil and crop productivity and biosafety of the adjacent agricultural fields has been missing in the literature. The objective of the current study was spatiotemporal quantification of productivity and biosafety threats of seasonal TSW leachate to recurrent corn and potato food crops in the adjoining agricultural fields of TSWOD of combined effluent plant of KTWMA, Kasur Pakistan. Based on data collected from two agricultural fields (2 ha each), it was observed that: (1) the TSW leachate arising from TSWOD severely affected soil productivity potential due to its immoderate pH, EC, COD, and BOD; being significantly higher than the local irrigation water; (2)Cd, Cr. Cu, Mn, Ni, Na and K in the TSW leachate exceeded the provincial industrial effluent discharge limits and had significant impact on soil health than the non-polluted fields; (3) the productivity of corn and potato in polluted fields remained as low as one third of the productivity in non-polluted fields; (4) the environmental contaminants’ food biosafety hazards were determined as metal pollution index being variable for different metals, hazard index (HI < 1.0), and risk quotient (chronic risk with 1.0 level of concern). (4) Statistically, the productivity decline of corn and potato crops was function of the changes in soils chemistry. The study concluded that TSWOD seasonal leachate increasingly reduced suitability of adjoining soils for safer edible cropping by significantly reducing productivity and posing long-term biosafety hazards caused by vulnerability of food chain to heavy metals and organic pollutants. Graphical abstract

The high content of toxic metals (TMs) in tannery solid waste (TSW) necessitates a synergistic approach for its remediation. The research focused on the derivation of TSW biochar and its autochthonous microbes as an integrated approach for phytoextraction of TMs. For this, TSW autochthonous strains of Bacillus and Trichoderma viride were used alone and in combination with TSW biochar treatments of 2.5, 5, and 10% (w/w), namely; BC1, BC2, BC3. Surface analyses of TSW biochar through SEM and FTIR demonstrated the agglomeration and deposition of inorganic moieties and exchangeable functional sites on the biochar surface. The combined treatment of TSW biochar along with Bacillus and T. viride revealed significantly improved TMs uptake (Cr 540.01 mg kg^-1 > Cd 380.44 mg kg^-1 > Pb 224.44 mg kg^-1) and plant biomass at 10% TSW biochar amendment. However, TMs content was found below the limit of detection (LOD) in seeds of sunflower. Biochemical responses such as total soluble protein content (73.61%), total chlorophyll content (12.69%), catalase (80.66%), and superoxide dismutase (82.31%) were improved under treatment assisted with microbial inoculum as compared to control. This integrated method promotes environmental sustainability and agricultural production by addressing the challenges associated with handling of TSW.

Untreated tannery wastewater (UTW) poses unprecedented threats to the aquatic and irrigation systems due to severely limited pollution removal efficiency (RE %) by the limited capacity and design of wastewater treatment plants in developing countries. An exploitation of treatment wetlands (TWs) like floating treatment wetlands (FTWs) face hydraulic performance and survivability and establishment challenges of transplanted hydrophytes in the severely toxic UTW. Such challenges were overcome by designing a horizontal flow floating treatment wetland (HFFTW) and diluting UTW at 0, 25, 50, and 75 with harvested rainwater (HRW), viz. UTW:HRW (% v:v) for lowering phytotoxicity to the phytotolerance range of the tested hydrophytes, viz. Eichhornia crassipes (EC) and Pistia stratiotes (PS) in the HFFTW, i.e., EC-HFFTW and PS-HFFTW. Both hydrophytes showed heavy metals’ translocation factor being ≥1, i.e., and acted as excellent hyperaccumulators of heavy metals. The average metal RE (%) was 64 (Cr), 61 (Cd), 45 (Pb), 44 (Cu), and 50.1 (BOD) for E. crassipes, and 44 (Cr), 54 (Cd), 42.2 (Pb), 42 (Cu), and 40 (BOD) for P. stratiotes. Significant reductions in the organic pollution load witnessed by significant drops in BOD and COD made UTW a safer irrigation medium for Petunia hybrida while inducing an increase in the bioconcentration factor (BCF) of PS and EC. The study concluded that the designed HFFTW showed significantly greater RE (%) and yield of reclaimed water than conventional FTWs based on its hydraulic performance. The design HFFTW carries a field scale application capacity for improvising treatment efficiency of the combined effluent plant of KTWMA (Kasur Tannery Waste Management Agency), Kasur, Pakistan.

Like other parts of the world, the source-specific generation of MSW in higher education institutes (HEIs) of Pakistan contain ≥ 70% compostables being managed through CMSWMS, a resource exhaustive environmental degradation approach. CMSWMS in the University of the Punjab, Lahore- 54590, a mother HEI in Pakistan, includes MSW containing over 2/3rd compostables (with ≥ 85% moisture contents) carrying poor collection efficiency and disposal at distantly located open dumps with linear economy. Here, DMSWMS effectiveness compared to CMSWMS was based on composting compostables at source-level to observe variations in the composition and characteristics of the MSW components, collection efficiency, cost, and combustibles’ earlier separation-driven impacts on its drying duration and calorific value for refuse-derived fuel (RDF), and assessing LCA-based acidification potential of carriage and disposal. Compared to CMSWMS, composting-based DMSWMS significantly improved characteristics of the compostables, combustibles, and recyclables. The DMSWMS resulted ≥ 97% collection efficiency, 89% reduction in collection and disposal cost, significant reduction in acidification potential through ≥ 94% GHGEs reduction, and rendered upfront availability of combustibles as RDF with 86% greater GCV. Cumulatively, all the DMSWMS-driven improvisations led the selected HEI in achieving 100% weighing score of MSWM component of the UI Green Metric World University Campus Ranking system. However, for prompting composting-based sustainable DMSWMS at broader scale in a city, multiple studies are required with stakeholders on board from union councils (smallest administrative units analogic to counties), which would streamline DMSWMS integration into MSW sanitation policy framework of municipalities.

Constructed wetland systems (CWSs) can offer cost-effective wastewater treatment in developing countries like Pakistan. This study focused on optimizing design and operational parameters of CWSs in horizontal surface flow (HSF), vertical surface flow (VSF), and hybrid mesocosms for treating sewage and textile effluents using local hydrophytes: Lemna minor, Typha latifolia, and Eichhornia crassipes. Pollutants and heavy metals (Cd, Cr, Cu, Pb, Ni, and Zn) were removed under different flow configurations, bedding materials, hydrophyte species, and hydraulic retention times (HRT) to optimize the overall contaminant removal efficiency (RE). Key findings indicated that the hybrid CWS achieved a maximum RE of 63.62% for total suspended solids (TSS) and 57.9% for biochemical oxygen demand (BOD) at an HRT of 3 days, with efficiencies declining at longer retention times. Additionally, the hybrid system showed maximum metal removal, with Cd and Cr RE reaching 75.2% and 70.5%, respectively. The study also highlighted the critical role of hydrophyte species and HRT in optimizing RE. Furthermore, the choice of hydrophyte species significantly influenced pollutant removal, with treatment cells containing mixed hydrophytes achieving the highest removal efficiencies (63.62%), followed by Eichhornia crassipes with high Cd (643.33 mgkg⁻¹) and Cr (1103.72 mgkg⁻¹) uptake. A lower HRT of 3 days resulted in the highest overall removal efficiency of 57.5%, which decreased with longer HRTs (from 6 to 9 days). Optimizing design and operational parameters is crucial for maximizing CWS treatment potential.

The present study aimed at converting meat industry waste, particularly waste bones and chicken feathers, into biochar to recycle valuable nutrients present in it, which ultimately become part of the municipal waste. The bone biochar (BB) and feathers biochar (FB) were prepared at 550 °C, and their potential was evaluated as an organic amendment for the growth of sunflower. The ash content (AC) and fixed carbon (FC) improved significantly in prepared biochars as compared to raw feedstock. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses signaled the occurrence of various functional groups viz. amide group and hydroxyapatite, porosity, and multiple nutrients. Application of BB and FB in potted soil alone as well as in composites (1:1, 1:2, 2:1) at 1%, 3%, and 5% (w/w) and synthetic fertilizer significantly increased soil pH, electrical conductivity (EC_e), organic matter (OM) and water holding capacity (WHC), while reducing the bulk density (BD). The growth of plants grown in soil treated with a 2:1 composite of feathers and bone biochar at 5% application rate showed significantly greater differences in plant height, total chlorophyll content, and plant dry weight than the control but was comparable to growth with chemical fertilizer, rendering it a potential alternative to chemical-based synthetic fertilizer.

Cotton gin trash, the by-product of the cotton ginning industry which is produced in large quantities every year, can be utilized as feedstock for deriving high quality organic materials such as biochar, compost and co-composted derivates for improvement of soils’ key physical, chemical and biological properties. This is the first report in which cotton gin trash was both thermally and biologically converted at the same time into biochar (BC), compost (C) and co-compost (Coc), and their effects on soil properties and on plant performance were examined. In order to find the optimum rate, the products were used as soil amendments in a greenhouse experiment at 2.5 t ha⁻¹, 5 t ha⁻¹and 10 t ha⁻¹ rates. All of the amendments contributed in improving the soil properties and provided agronomic benefits to plants, however plants (radish var. Cherry belle) showed significantly (p < 0.05) better growth attributes and almost a 315% increase in biomass yield observed when co-composted biochar (10 t ha⁻¹) was applied to the soil, thus suggesting its role in compensating fertilizer application. Amendments (2.5 and 5.0 t ha⁻¹) considerably increased plant growth parameters; however, differences between 5 and 10 t ha⁻¹ amendments were not so significant. As a result, replenishing soil with Coc (5 t ha⁻¹) on a regular basis can promote plant growth and improve soil qualities over time.

The current research encompasses utilization of peanut shells (PS) as feedstock for pyrolysis carried out at various temperatures (250, 400, and 550 °C) for deriving biochar, namely PS-BC250, PS-BC400, and PS-BC550. After analyzing the biochar types physicochemically, it was applied as a soil ameliorant for the growth of cucumber. The results showed that in prepared biochar type, bulk density, volatile contents, hydrogen, oxygen, and nitrogen content decreased, whereas pH, electrical conductivity, ash content, fixed carbon content, and surface area increased with the increasing temperature. Scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) presented high porosity, re-orientation of vessels, and a greater number of aromatic compounds, respectively, for PS-BC prepared at 550 °C. On applying PS-BC250, PS-BC400, and PS-BC550 as amendments in potted soil at 2, 4, and 6% (w/w), it improved soil quality (viz pH, EC_e, BD, and soil water holding capacity) and increased the yield of cucumber. Because of improved soil properties and crop yield, PS-BC550 at the rate of 4% (w/w) demonstrated a great potential for agricultural application while provisioning dual circular economic indicators in the form of diverting PS waste to an effective alternative of chemical fertilizer having intensive carbon footprints in cucumber production.

The current study is aimed at deriving biochar (BC) from rice straw (RS-BC) and waste bones (WB-BC), being wasted without adequate return at the expense of environmental degradation. The RS and WB feedstocks were pyrolyzed at 550 °C, and the potential of derived biochar as a slow nutrient releasing soil amendment was examined during the growth of ridge gourd. Proximate analysis of the prepared biochars showed significant improvement in ash content and fixed carbon as compared to their raw biomasses. Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analysis of RS-BC and WB-BC displayed a diverse range of functional groups viz. derivatives of cellulose and hydroxylapatite (HA); macro and microporosity; multiple nutrients. Application of RS-BC and WB-BC in potted soil alone and as biochar composite (RS-BC+WB-BC) at 5, 10 and 15% (w/w) and chemical fertilizer (CF) resulted in a significant increase in soil pH, electrical conductivity (ECe), cation exchange capacity (CEC) and water holding capacity (WHC) in exchange for growth and yield of ridge gourd. However, there were insignificant differences in the growth of plants in response to RS-BC, WB-BC alone and CF with biochar composite at 15% amendment. For giving insignificantly different growth results than CF, the prepared biochar composite showed outstanding potential as an organic fertilizer applicable in agrarian soils to elevate soil properties and yield of agricultural commodities.