Water consumption management in polyethylene terephthalate (PET) bottles washing process via wastewater pretreatment and reuse

Removal of Pb(II), Cd(II) and Ni(II) Ions from Groundwater by Nonthermal Plasma

The removal of Pb(II), Cd(II) and Ni(II) ions from aqueous solutions by means of nonthermal plasma with a dielectric barrier discharge is investigated. Aqueous solutions with metal ion concentrations from 10 to 100 mg/dm³ in spring water were used. In the first stage, the optimization of the solution flow rate, generator modulation frequency and duty cycle was made in terms of the removal efficiency of the considered metals. The removal was then investigated as a function of the number of passes of the solution through the cold plasma reactor. The effect of the initial concentration of ions in the solution was studied. Techniques such as composite central design, least squares method and Fourier transform infrared spectroscopy were used. The physical and chemical parameters of the solutions, such as electrical conductivity, pH, temperature, concentration of metal ions and the content of other substances (e.g., total organic carbon), were measured, and the presence of microorganisms was also examined. It was found that each pass of the solution through the cold plasma reactor causes a decrease in the concentration of Cd(II) and Ni(II); the concentration of Pb(II) drops rapidly after one pass, but further passes do not improve its removal. The removal percentage was 88% for Cd(II) after six passes and 72% for Pb(II) after one pass, whereas 19% for Ni(II). The purification mechanism corresponds to the precipitation of metal ions due to the increasing pH of the solution after exposure to cold plasma.

Treating and reusing wastewater generated by the washing operations in the non-hazardous plastic solid waste recycling process: Advanced method vs. conventional method

The effectiveness of an advanced treatment of wastewater generated by non-hazardous plastic solid waste (PSW) washing, based on the Sequencing Batch Biofilter Granular Reactor (SBBGR), was assessed in terms of gross parameters, removal efficiencies and sludge production. The proposed treatment was also compared with the conventional treatment, which was based on primary and secondary treatments, using the activated sludge process, performed by Recuperi Pugliesi, a leading company in the plastic recycling industry located in Bari, Italy. The company produces low-density polyethylene (LDPE) regenerated granules from PSW used in agricultural and floricultural greenhouse activities and industrial packaging after a washing stage in the aqueous phase. The latter generates large volumes of wastewater, the conventional treatment of which is characterised by large quantities of sludge and the associated disposal problems. Under steady-state conditions, the SBBGR provided impressive removal efficiencies regarding the main gross parameters (over 90% for COD and TKN, over 99% for BOD₅, TSS, VSS and NH₃, and over 80% for TN) with a statistically better effluent quality than that of the conventional treatment. The SBBGR effluent quality was modelled in terms of washing water characteristics by using generalized additive models (GAMs). The SBBGR treatment was characterised by a specific sludge production five times lower than that of the conventional treatment (0.21 kg TSS vs. 1.0 kg TSS per m³ of wastewater treated). Compared with the conventional treatment, the proposed process showed a five-fold reduction in the cost of sludge disposal, which saved 50% of the operating cost.

Water reclamation and reuse

Literature published in 2018 pertinent to water reclamation and reuse has been classified into five topics: safe reuse, treatment technologies, management, assessment, and case studies. Researches have been conducted to develop new technologies and improve conventional treatments for achieving sustainable wastewater reclamation, and increasing efforts have been made to facilitate safe water reuse. PRACTITIONER POINTS: The way of publicity greatly influences people's acceptance of water reuse and willingness to purchase produce irrigated with recycled water. Integrated process is the most commonly used treatment technology to reclaim water. There is a lack of local or regional regulatory and policy for sustainable water management.