Lead (Pb) deposition onto new and biofilm-laden potable water pipes.

Heavy metals' interactions with plumbing materials are complicated due to the differential formation of biofilms within pipes that can modulate, transform, and/or sequester heavy metals. This research aims to elucidate the mechanistic role of biofilm presence on Lead (Pb) accumulation onto crosslinked polyethylene (PEX-A), high-density polyethylene (HDPE), and copper potable water pipes. For this purpose, biofilms were grown on new pipes for three months. Five-day Pb exposure experiments were conducted to examine the kinetics of Pb accumulation onto the new and biofilm-laden pipes. Additionally, the influence of Pb initial concentration on the rate of its accumulation onto the pipes was examined. The results revealed greater biofilm biomass on the PEX-A pipes compared to the copper and HDPE pipes. More negative zeta potential was found for the biofilm-laden plastic pipes compared to the new plastic pipes. After five days of Pb exposure under stagnant conditions, the biofilm-laden PEX-A (980 µg m-2) and HDPE (1170 µg m-2) pipes accumulated more than three times the Pb surface loading compared to the new PEX-A (265 µg m-2) and HDPE pipes (329 µg m-2), respectively. However, under flow conditions, Pb accumulation on biofilm-laden plastic pipes was lower than on the new pipes. Moreover, with increasing the initial Pb concentration, greater rates of Pb surface accumulation were found for the biofilm-laden pipes compared to the new pipes under stagnant conditions. First-order kinetics model best described the Pb accumulation onto both new and biofilm-laden water pipes under both stagnant and flow conditions.

Effects of water chemistry and flow on lead release from plastic pipes versus copper pipes, implications for plumbing decontamination.

Despite being corrosion-resistant, plastic potable water pipes might accumulate heavy metals on their surface if they convey metal-contaminated tap water. This study examined the influence of water pH and flow conditions on lead (Pb) release from new and biofilm-laden potable water pipes to provide insights regarding decontamination. For this purpose, biofilms were grown onto new crosslinked polyethylene (PEX-A), high-density polyethylene (HDPE), and copper pipes for three months. Lead was then deposited onto the new and biofilm-laden pipes through 5 d exposure experiments under flow conditions. After that, lead release experiments were conducted by exposing the lead-accumulated pipes to lead-free synthetic tap water for 5 d, under both stagnant and water flow conditions. The metal accumulation study showed no significant difference in lead uptake by new pipes and their biofilm-laden counterparts under flow conditions. This could be attributed to the detachment of biofilms that have accumulated lead as water flows through the pipes. Water flow conditions significantly influenced the lead release from new and biofilm-laden water pipes. A lower water pH of 5.0 increased the release of lead from plastic pipes into the contact water, compared to pH 6.0 and 7.8. The greatest percentage of lead was released from biofilm-laden HDPE pipes (5.3%, 120 h) compared to biofilm-laden copper pipes (3.9%, 6 h) and PEX-A (3.7%, 120 h) and after exposure to lead-free synthetic tap water at pH 5.0, under stagnant conditions. On the other hand, under water flow conditions, the greatest lead release was found for new PEX-A pipes (4.4%, 120 h), new HDPE pipes (2.7%, 120 h), and biofilm-laden copper pipes (3.7%, 2 h).

Whole-Genome Sequence and Draft Assembly of the Biocontrol Fungal Pathogen Albifimbria verrucaria CABI-IMI 368023.

We report here the whole-genome sequence and draft assembly for a bioherbicidal strain of Albifimbria verrucaria, CABI-IMI 368023, which was formerly identified as Myrothecium verrucaria. This isolate has been well studied for the biological control of important weeds, including kudzu and giant salvinia.