Treated Greywater Reuse for Hydroponic Lettuce Production in a Green Wall System – Quantitative Health Risk Assessment

Abstract

Abstract:The scarcity and pollution of freshwater are extremely crucial issues today and the expansion of water reuse have been considered as an option to reduce its impact. This study aims to assess the efficiency of an integrated greywater treatment system and hydroponic lettuce production as a part of a green wall structure and to evaluate the health risk associated with the production and consumption of lettuce through quantitative microbial risk assessment (QMRA) and chemical health risk assessment. The study was conducted based on the unique configuration of source separation system; on-site greywater treatment system; green wall structure as a polishing step; and hydroponic lettuce production in the green wall structure. The final effluent from the system was used to grow three lettuce varieties by adding urine as a nutrient solution. Both water samples and plant biomass were collected and tested for E. coli and heavy metals contamination. The system has gained a cumulative 5.1 log10 reduction of E. coli in the final effluent and no E. coli found in the plant biomass. QMRA results indicated that the system attained the health-based targets, 10 -6 DALYs per person per year. Similarly, health risk index (HRI) and targeted hazard quotient (THQ) results did not exceed the permissible level, thus the chemical health risk concern was insignificant.

Exposure assessment of treated greywater reused for irrigation

“…However, Cu can be toxic to a number of plants at concentrations of 0.1-1.0 mg/L, and Zn can be toxic to many plants at widely varying concentrations, especially at 10 mg/L in reclaimed water, which requires short-term use (U.S. EPA 2012). This is similar to other research, which found that Zn and Cu were detected in the lettuce tissue at relatively high levels compared with the other elements (Eregno et al 2017). Pb accumulated at high levels in coriander in all plots.…”

Reviewing chemical and biological risks in urban agriculture: A comprehensive framework for a food safety assessment of city region food systems

“…Antimicrobial resistant strains of such pathogens were also of concern ( Aarestrup et al, 2008 ), especially in environments where continuous exposure to antimicrobials could induce resistance in microbiota ( Checcucci et al, 2020 ; García et al, 2020 ; Xi et al, 2015 ). Among protozoa, the addressed pathogens were mainly Cryptosporidium ( Eregno et al, 2017 ) and Giardia ( Srikanth & Naik, 2004 ).…”

Nutritive Solutions Formulated from Organic Fertilizers

“…In addition, more or less stabilized organic substances, if poorly preserved and stored, can serve as excellent substrates for pathogens and become carriers of infections [21].…”