The Toxicity of Aluminium Salts to Lecane Inermis Rotifers: Are Chemical and Biological Methods Used to Overcome Activated Sludge Bulking Mutually Exclusive?

Abstract

Abstract:The aim of this study was to assess the effects of two fl occulants that are often used to overcome activated sludge bulking problems -aluminium chloride, AlCl 3 , and aluminium sulphate, Al 2 (SO 4 ) 3 -on Lecaneinermis (Rotifera, Monogononta) at three different temperatures: 8, 15 and 20°C. The mean EC50 value (effective concentration, mg dm -3 ) calculated for the 24 h mortality test was 0.012 mg Al 3+ dm -3. Next, the effects of low concentrations of the Al-salts on the population development from single individuals (parthenogenetic females) were tested in a 21-day experiment. At concentrations as low as EC4.8 and EC0.48, both Al-salts affected rotifer population negatively. However, temperature was the most pronounced factor that modifi ed the toxicity of the Al-salts to the rotifers. On the 12 th day of the experiment, there were signifi cant interactions between temperature and the Al-salts, indicating that the chemicals were more toxic to the rotifers at 20°C than at lower temperatures. The weaker rotifers sensitivity to Al-salts (especially to AlCl 3 ) in temperatures below 15°C, when the biggest problems associated with sludge bulking occurs,may means use both rotifers and chemicals reasonable and effective.

Cost Effective Method for Toxicity Screening of Pharmaceutical Wastewater Containing Inorganic Salts and Harmful Organic Compounds

“…In experiments were aluminium salts (AlCl3, Al2(SO4)3) were using to improve settlement characteristics of the sludge and overcome the bulking problem, it was found that aluminium is toxic to activated sludge rotifer Lecane inermis and affected negatively rotifers population size even at low concentrations (4.8 EC and 0.48 EC) [47].…”

Effects of polyaluminum chloride (PAX-18) on the relationship between predatory fungi and Lecane rotifers

“…There are different types of malfunctions resulting in solid separation problems. Among them are as follows: dispersed growth of microorganisms when they do not stick together, formation of pinpoint flocs (PP) when only very small, and mechanically fragile flocs are present; and zoogleal bulking caused by excessive amount of extracellular material (EPS) produced by microorganisms (Jenkins et al 2003;Mesquita et al 2011). However, the most common problem of liquid-solid separation is activated sludge bulking caused by an overproliferation of filamentous bacteria (Eikelboom 2000;Jenkins et al 2003).…”

“…Among them are as follows: dispersed growth of microorganisms when they do not stick together, formation of pinpoint flocs (PP) when only very small, and mechanically fragile flocs are present; and zoogleal bulking caused by excessive amount of extracellular material (EPS) produced by microorganisms (Jenkins et al 2003;Mesquita et al 2011). However, the most common problem of liquid-solid separation is activated sludge bulking caused by an overproliferation of filamentous bacteria (Eikelboom 2000;Jenkins et al 2003). To limit the development of such bacteria, WWTPs operators use various coagulants such as ferrous chloride, ferric chloride, hydrated aluminum sulfate, polyaluminum chloride, or cationic polymers (Jenkins et al 2003;Mamais et al 2011).…”

“…However, the most common problem of liquid-solid separation is activated sludge bulking caused by an overproliferation of filamentous bacteria (Eikelboom 2000;Jenkins et al 2003). To limit the development of such bacteria, WWTPs operators use various coagulants such as ferrous chloride, ferric chloride, hydrated aluminum sulfate, polyaluminum chloride, or cationic polymers (Jenkins et al 2003;Mamais et al 2011). However, so far, no method is 100% efficient.…”

“…Given that a predatory fungus could be a real threat for beneficial rotifers, we aimed to test how PAX affects two distinct genera of fungi feeding on rotifers: Lecophagus and Zoophagus , when applied at aluminum ion concentrations recommended for bulking control. As it was shown that rotifers such as L. inermis are vulnerable to aluminum ions present in simple salts (Klimek et al 2013 ), we also decided to check if the application of PAX in a concentration lower than recommended for bulking control could have an indirect positive effect on rotifers in activated sludge by suppressing predatory fungi.…”