Cleaner production auditing for plastic recycling industry in Pakistan: A baseline study

Recycling plastics is a good alternative to manage the plastic waste generated in Pakistan. Unfortunately, the country lacks efficient system to manage or recycle the plastic waste it generates. Lack of government support, absence of standard operating procedures, negligence towards health and safety of workers, increasing costs of raw materials and poor quality of the recyclates are some of the issues currently faced by plastic recyclers in Pakistan. Considering the need of cleaner production audits in plastic recycling industries, this study was carried out to establish an initial reference benchmark. Production processes in 10 recycling industries were evaluated from cleaner production perspective. The study showed the average water consumption of a recycling industry as high as 3315 L/ton. All the consumed water is wasted in the nearby community sewer while, only 3 recyclers recycled between 70 and 75% the treated wastewater. In addition, a recycling facility on an average consumed 172.5 kWh of power for processing 1 ton of plastic waste. The average temperature was observed to be 36.5 °C and noise levels exceeded the permissible limits. Moreover, the industry is male-dominated, workers are mostly underpaid and have no access to good healthcare facilities. Recyclers lack standardization and have no national guidelines to follow. Guidelines and standardization of recycling process, wastewater treatment, use of renewable energy, water reuse etc, are direly needed for uplifting this sector and reducing its impacts on the environment.

Wastewater generation and treatment by various eco-friendly technologies: Possible health hazards and further reuse for environmental safety

The discharge of untreated wastewater as a result of various developmental activities such as urbanization, industrialization and changes in lifestyle poses great threats to aquatic ecosystems as well as humans. Currently, ∼380 billion m³ (380 trillion liters) of wastewater is generated globally every year. Around 70% of freshwater withdrawals are used for agricultural production throughout the world. The wastewater generated through agricultural run-off further pollutes freshwater resources. However, only 24% of the total wastewater generated from households and industries is treated before its disposal in rivers or reused in agriculture. The most problematic contaminants associated with ecological toxicity are heavy metals such as Cd, Cr, Cu, Ni, Zn, Fe, Pb, Hg, As and Mn. One of the most important issues linked with wastewater generation is the residual presence of pathogenic microorganisms which pose potential health hazards to consumers when they enter into the food chain. It is estimated that in India almost USD 600 million (48.60 billion INR) is spent per year to tackle waterborne diseases (WBD). In light of this, immediate action is needed to effectively treat wastewater and develop safer reuse prospects. Various wastewater treatment technologies have been established and they work well to provide an alternative water source to meet the growing demand. The main concern towards treating wastewater is to eliminate inorganic and organic substances and lower the nutrient concentration, total solids, and microbial pathogens to prevent freshwater pollution and health risks.

Finding new sources of water for semi-arid cities in unlikely places

Determining alternative water sources to meet municipal water demands is important when availability is limited. The purpose of this study was to demonstrate a means for water planners to estimate the amount of combined sanitary wastewater and storm water that they might already be capturing through open air oxidation ponds. Increased understanding of the quantity of water that is already available could help water planners to better envision optimal water reuse scenarios. Using water and climate data on oxidation ponds in these three cities within the Texas Panhandle from 2010 to 2014, we evaluated water quantities which would be available for potential reuse. From the net monthly wastewater volumes values, the study also considered if per capita demand could have been met by reusing the wastewater. The study found wastewater volumes were lower in fall and winter months and much higher in spring and summer months. If a city considers reusing wastewater, blue water (groundwater) extraction could be reduced by as low as 45-50% in one city to as high as 100% in another. Water planners in similar environments and wastewater treatment systems may find this demonstration of potential reuse water quantity encouraging for better meeting their own water demands and enhancing water supply resiliency.

Maximizing cellulosic ethanol potentials by minimizing wastewater generation and energy consumption: Competing with corn ethanol

Energy consumption and wastewater generation in cellulosic ethanol production are among the determinant factors on overall cost and technology penetration into fuel ethanol industry. This study analyzed the energy consumption and wastewater generation by the new biorefining process technology, dry acid pretreatment and biodetoxification (DryPB), as well as by the current mainstream technologies. DryPB minimizes the steam consumption to 8.63GJ and wastewater generation to 7.71tons in the core steps of biorefining process for production of one metric ton of ethanol, close to 7.83GJ and 8.33tons in corn ethanol production, respectively. The relatively higher electricity consumption is compensated by large electricity surplus from lignin residue combustion. The minimum ethanol selling price (MESP) by DryPB is below $2/gal and falls into the range of corn ethanol production cost. The work indicates that the technical and economical gap between cellulosic ethanol and corn ethanol has been almost filled up.