The use of ceramic membranes in the treatment and processing of various liquids, including those of organic origin, has increased tremendously at the industrial level. Apart from the selection of the most appropriate membrane materials and operational conditions, suitable membrane cleaning procedures are a must to minimize fouling and increase membrane lifespan. The review summarizes currently available and practiced non-reagent and cleaning-in-place methods for ceramic membranes that are used in the treatment of organic liquids, thus causing organic fouling. Backflushing, backwashing, and ultrasound represent the most often used physical methods for reversible fouling treatment. At the same time, the use of alkalis, e.g, sodium hydroxide, acids, or strong oxidants are recommended for cleaning of irreversible fouling treatment.

The inhibition effect of rapid variations of pH in wastewater on activated sludge was investigated in laboratory-scale sequencing batch reactors (SBR). The toxic influence of pH 6.5 and 8.5 was examined. The experiment with pH 8.5 was preferable to formation of high FA concentration and showed a low risk of inhibition of second step nitrification (conversion of nitrites to nitrates). However, the reactor at pH 6.5 showed inhibition of first-step nitrification (conversion of ammonia to nitrites) caused by FNA formation. High ammonia levels caused a decrease in the overall microfauna population, whereas low–enhanced gymnamoebae, Zoogloea, and Chilodonella sp. population increased after 72 h of inhibition. Destructive acidic pH influence caused sludge washout from the reactor and, therefore, higher organic load on ASP and intensive sludge foam due to Zoogloea higher population.

Advanced oxidation processes, such as the Fenton's reagent, are powerful methods for decontamination of different environments from recalcitrant organics. In this work, the degradation of paraquat (PQ) pesticide was assessed (employing the commercial product gramoxone) directly inside the pipes of a pilot scale loop system; the effect of corroded cast iron pipe and loose deposits for catalysing the process was also evaluated. Results showed that complete degradation of paraquat ([PQ]0= 3.9 × 10−4 M, T = 20–30 °C, pH0 = 3, [H2O2]0 = 1.5 × 10−2 M and [Fe (II)] = 5.0 × 10−4 M,) was achieved within 8 h, either in lab scale or in the pilot loop. Complete PQ degradation was obtained at pH 3 whereas only 30% of PQ was degraded at pH 5 during 24 h. The installation of old cast iron segments with length from 0.5 to 14 m into PVC pipe loop system had a significant positive effect on degradation rate of PQ, even without addition of iron salt; the longer the iron pipes section, the faster was the pesticide degradation. Addition of loose deposits (mostly corrosion products composed of goethite, magnetite and a hydrated phase of FeO) also catalysed the Fenton reaction due to presence of iron in the deposits. Moreover, gradual addition of hydrogen peroxide improved gramoxone degradation and mineralization. This study showed for the first time that is possible to achieve complete degradation of pesticides in situ pipe water system and that deposits and corroded pipes catalyse oxidation of pesticides.

The use of wastes for developing of new materials is a sustainable approach. In current study filter media produced from industrial waste was tested for an ability to decrease high concentration of zinc in standard solution and industrial wastewater. The geopolymer production requires mixing of post-industrial waste with naturally occurred aluminosilicate materials by using binding agent at the ambient or slightly increased temperature in order to produce a long lasting eco-friendly cementitious material. The tested media decreased concentration of zinc in standard solution from 72,9 to 19,6 mg/L in 30 min showing similar performance as commercially available zeolite material. In experiments with wastewater the adsorption of Zn by AAM was much lower, which can be explained by the fact that wastewater contained generous amounts of different metal ions, organic substances and oils. Despite complex composition of wastewater AAM was able to immobilize at minimum 22 mg/L (32%) Zn from the solution.

Biofouling triggers a chain of events that are deleterious to engineered systems providing safe water to the population and industry. The frequent use of dissolved biocides to combat biofilm growth has its own drawbacks, including the formation of noxious substances (e.g., organochlorinated compounds) and the discharge of significant amounts of nonspent biocides in the aquatic environment. This paper proposes affordable and robust approaches for water pretreatment to reduce organic (bio) and inorganic fouling to be implemented in developing rural areas. The pretreatment follows a sequential step strategy that includes particulate matter removal through optimized coagulation, phosphorus removal by iron oxide sorption using recovered inexpensive waste materials and, finally, an innovative biocidal treatment with functionalized particles. The following main experimental results were obtained: (1) coagulation treatment with aluminum sulfate at ${0.03\mathrm{mg}\mathrm{L}}^{-1}$ led to the elimination of particulate matter fouling, as confirmed by the improved performance of a downstream membrane separation system; (2) in the sorption step, iron-covered waste sand taken from filter backwash water allowed a reduction of microbial available phosphorous to levels where biofilm growth is highly limited; and (3) the novel bactericidal process, using inexpensive commercial alumina particles functionalized with benzalkonium chloride, was able to reduce to zero the microbial load of a contaminated water stream within 1 h of residence time, without leaching the biocide to the water. Implementation of this concept represents an affordable and environmentally sustainable treatment system because the basic materials used have low cost and are easily available.