Household discharge of chemical products and its classification based on anaerobic biodegradability.

Synthetic household chemical products (HCP) are used in various household activities. An average urban household was estimated to consume ~ 3 kg HCP per month while discarding 212-387 mg/L HCP in sewage comprising > 265 different chemical compounds. The high sorption properties of HCP and their antimicrobial resistance lead to their long-term persistence in the environment. The intrusion of HCPs and their breakdown products into food chain causes detrimental effects on health and ecology. HCPs comprise mostly of a mixture of xenobiotics, organic and inorganic compounds resulting in an impaired biodegradation. Yet, the biodegradability of HCPs is seldom assessed. Therefore, this research proposes a modified Gompertz model approach to analyze BMP data in order to classify commercially available HCPs into seven groups based on the observed levels of recalcitrance and is in turn coined "Anaerobic Biodegradability Index" (ABI, beginning from ABI-VI to ABI-0 wherein ABI-VI represents the highest degradability and ABI-0 the least). This approach emulates "Energy-Star" ratings of electrical appliances classified based on electrical efficiency. Results of such a classification indicated that HCPs containing ≥ 10% anionic surfactants such as laundry detergents, handwash gel, dishwasher chemicals, and creosote surface cleaner, exhibit lowered anaerobic degradability and were therefore categorized between ABI-0 and ABI-II. Whereas the highly degradable HCP such as toothpaste, shower gel, and hair shampoo were categorized in ABI-V and ABI-VI categories. We perceive that the weightages and concentrations can be used in the future to define the capability of various wastewater treatment systems and their tolerance to various ABI classes.

The physicochemical characteristics and anaerobic degradability of desiccated coconut industry waste water.

Desiccated coconut industries (DCI) create various intermediates from fresh coconut kernel for cosmetic, pharmaceutical and food industries. The mechanized and non-mechanized DCI process between 10,000 and 100,000 nuts/day to discharge 6-150 m(3) of malodorous waste water leading to a discharge of 264-6642 kg chemical oxygen demand (COD) daily. In these units, three main types of waste water streams are coconut kernel water, kernel wash water and virgin oil waste water. The effluent streams contain lipids (1-55 g/l), suspended solids (6-80 g/l) and volatile fatty acids (VFA) at concentrations that are inhibitory to anaerobic bacteria. Coconut water contributes to 20-50% of the total volume and 50-60% of the total organic loads and causes higher inhibition of anaerobic bacteria with an initial lag phase of 30 days. The lagooning method of treatment widely adopted failed to appreciably treat the waste water and often led to the accumulation of volatile fatty acids (propionic acid) along with long-chain unsaturated free fatty acids. Biogas generation during biological methane potential (BMP) assay required a 15-day adaptation time, and gas production occurred at low concentrations of coconut water while the other two streams did not appear to be inhibitory. The anaerobic bacteria can mineralize coconut lipids at concentrations of 175 mg/l; however; they are severely inhibited at a lipid level of ≥350 mg/g bacterial inoculum. The modified Gompertz model showed a good fit with the BMP data with a simple sigmoid pattern. However, it failed to fit experimental BMP data either possessing a longer lag phase and/or diauxic biogas production suggesting inhibition of anaerobic bacteria.

Luffa cylindrica (Sponge Gourd) Fibers in Treatment of Greywater: an Aerobic Fixed-Film Reactor Approach.

The need for potable water consumption in urban and suburban regions can be decreased by greywater treatment and its reuse. Utilizing natural fibers may provide sustainable solutions in addressing challenges related to water resource management. In this study, a fixed-film reactor was designed with Luffa cylindrica (an annually occurring fruit) as a bio-carrier. The lab-scale reactors were configured with and without Luffa cylindrica and were run for 90 days in fed-batch mode. Scanning electron microscopy (SEM) was performed to validate biofilm production over time. Monitoring COD, nitrogen, and total phosphate removal allowed for analysis of treatment effectiveness. Results demonstrated the treatment efficiency for the experimental reactor was 70.96%, 97.02%, 92.57%, and 81.20% for COD, nitrogen, phosphate, and anionic surfactant (AS), respectively. 16 s rRNA gene sequencing of bio-carrier and control greywater samples was carried out. Many bacteria known to break down anionic surfactants were observed, and microbial succession was witnessed in the control reactor vs. the experimental reactor samples. The three most prevalent genera in the experimental samples were Chlorobium, Chlorobaculum, and Terrimonas. However, it is crucial to underscore that additional research is essential to solidify our understanding in this domain, with this study laying the fundamental groundwork.

Accumulation of antibiotic-resistant genes in anaerobic biofilm reactor fed with household chemical products.

This research aims to determine the presence of antibiotic-resistant genes (ARG) in anaerobic biofilm reactors (ABR) fed with household chemical products (HCP) such as laundry detergents and handwash without any influx of antibiotics. The ABR comprised a three-chamber design with bottom sludge, a middle chamber containing fluidized PVC spiral, and a top chamber with packed coir fiber as a biofilm support medium, respectively. Four different ABRs were simultaneously operated for a prolonged period (200 day) and subjected to variations in physicochemical conditions. The ABRs fed with HCP exhibited solitary accumulation of log (4.4-7.5) ermC gene copies/g VS whereas, ARG was undetectable in glucose fed ABRs indicating that HCP exhibited antimicrobial activities synonyms to Erythromycin. Accumulation of Erythromycin-C (ermC) was relatively higher on the biofilm inhabiting PVC support medium and further accentuated by effluent recycling to log 7.5 ermC gene copies at a ratio of ermC/16S gene copies of 0.65. Physico-chemical factors such as substrate composition, biofilm support medium, and effluent recycling simultaneously elevated the concentration of ermC genes. The results indicated that HCP augments the accumulation of ARG in the microbiome, subsequently, increasing the risk in ARG transmission from sewage treatment plants to the ecology and humans.