Helvi Heinonen-Tanski

Elimination of enteric bacteria in biological-chemical wastewater treatment and tertiary filtration units

The occurrence and removal of salmonellae and faecal indicators in four conventional municipal wastewater treatment plants (MWTP) were investigated. In addition, we tested the efficiency of a semi-technical scale biological nutrient removal process and three pilot-scale tertiary filtration units in microbial removal. All influent samples collected from MWTPs contained salmonellae from 93 to 11,000 MPN/100 ml and indicator bacteria from about 10(7) to 10(8) CFU/100 ml. The reductions in salmonella numbers achieved in full-scale biological-chemical wastewater treatment and semi-technical scale biological nutrient removal processes were usually between 94% and virtually 100% (99.9%) and indicator bacteria reductions between 2 and 3 log units. Microbial numbers in MWTP effluents could be modelled as a function of effluent residual organic matter, suspended solids and total phosphorus concentrations. Pilot-scale tertiary treatment by rapid sand contact filter, chemical contact filter and biological-chemical contact filter reduced salmonella numbers below the detection limit and faecal coliform numbers on average by 99%, 39% and 71%, respectively. A total of 32 Salmonella serovars were identified among 197 Salmonella isolates from municipal wastewaters. Of the isolates, 32% were resistant to nalidixic acid, indicating reduced sensitivity to ciprofloxacin, the drug of choice in the treatment of salmonellosis. In addition, 18% of the isolates were multiresistant. Our results, especially antibiotic resistant Salmonella strains, indicate that conventional municipal wastewater treatment without efficient tertiary treatment, like filtration or disinfection, may constitute a risk for public health.

Filter Performance of N99 and N95 Facepiece Respirators Against Viruses and Ultrafine Particles

Abstract The performance of three filtering facepiece respirators (two models of N99 and one N95) challenged with an inert aerosol (NaCl) and three virus aerosols (enterobacteriophages MS2 and T4 and Bacillus subtilis phage)—all with significant ultrafine components—was examined using a manikin-based protocol with respirators sealed on manikins. Three inhalation flow rates, 30, 85, and 150 l min−1, were tested. The filter penetration and the quality factor were determined. Between-respirator and within-respirator comparisons of penetration values were performed. At the most penetrating particle size (MPPS), >3% of MS2 virions penetrated through filters of both N99 models at an inhalation flow rate of 85 l min−1. Inhalation airflow had a significant effect upon particle penetration through the tested respirator filters. The filter quality factor was found suitable for making relative performance comparisons. The MPPS for challenge aerosols was <0.1 μm in electrical mobility diameter for all tested respirators. Mean particle penetration (by count) was significantly increased when the size fraction of <0.1 μm was included as compared to particles >0.1 μm. The filtration performance of the N95 respirator approached that of the two models of N99 over the range of particle sizes tested (∼0.02 to 0.5 μm). Filter penetration of the tested biological aerosols did not exceed that of inert NaCl aerosol. The results suggest that inert NaCl aerosols may generally be appropriate for modeling filter penetration of similarly sized virions.

Airborne enteric coliphages and bacteria in sewage treatment plants.

The concentrations of airborne culturable microorganisms were determined in wastewater and sludge treatment processes of seven sewage treatment plants. Two types of coliphages, Salmonella and total viable bacteria were sampled by the BioSampler and the numbers of faecal coliforms and enterococci were obtained from the Andersen 6-stage impactor. The BioSampler recovered higher numbers of airborne coliphage viruses than has been measured with other liquid samplers in previous studies, suggesting that this sampler has improved efficiency for sampling airborne coliphages. Airborne coliphages were detected in many stages of the wastewater or sludge treatment process. The highest microbiological air contaminations were found in pre-treatment and aerated grit separation stages of the operation. This was attributed to aerosolisation of microorganisms by mechanical handling or forced aeration. Aeration and settling processes located outdoors caused low microbial concentrations, but the brush aerator released more microorganisms into the air. Our results emphasize the necessity for controlling the exposure of sewage workers to airborne microorganisms, especially in process areas that involve mechanical agitation or forced aeration of wastewater.

Stored Human Urine Supplemented with Wood Ash as Fertilizer in Tomato (Solanum lycopersicum) Cultivation and Its Impacts on Fruit Yield and Quality

This study evaluates the use of human urine and wood ash as fertilizers for tomato cultivation in a greenhouse. Tomatoes were cultivated in pots and treated with 135 kg of N/ha applied as mineral fertilizer, urine + ash, urine only, and control (no fertilization). The urine fertilized plants produced equal amounts of tomato fruits as mineral fertilized plants and 4.2 times more fruits than nonfertilized plants. The levels of lycopene were similar in tomato fruits from all fertilization treatments, but the amount of soluble sugars was lower and Cl(-) was higher in urine + ash fertilized tomato fruits. The beta-carotene content was greater and the NO(3)(-) content was lower in urine fertilized tomato fruits. No enteric indicator microorganisms were detected in any tomato fruits. The results suggest that urine with/without wood ash can be used as a substitute for mineral fertilizer to increase the yields of tomato without posing any microbial or chemical risks.

Human Urine and Wood Ash as Plant Nutrients for Red Beet (Beta vulgaris) Cultivation: Impacts on Yield Quality

The objective of this study was to evaluate the effect of human urine and wood ash fertilization on the yield and quality of red beet by measuring the microbial, nutrient, and antioxidant (betanin) content of the roots. Red beets were fertilized with 133 kg of N/ha as mineral fertilizer, urine and ash, and only urine with no fertilizer as a control. The mineral-fertilized plants and urine- and ash-fertilized plants also received 89 kg of P/ha. Urine and ash and only urine fertilizer produced 1720 and 656 kg/ha more root biomass, respectively, versus what was obtained from the mineral fertilizer. Few fecal coliforms and coliphage were detected in mineral-fertilized and urine- and ash-fertilized red beet roots. The protein and betanin contents in red beet roots were similar in all treatments. In conclusion, this study revealed that urine with or without ash can increase the yield of red beet and furthermore the microbial quality and chemical quality were similar to the situation in mineral-fertilized products.

Co-digestion of dairy cattle slurry and industrial meat-processing by-products--effect of ultrasound and hygienization pre-treatments.

Anaerobic co-digestion of a mixture of industrial animal by-products (ABP) from meat-processing in conjunction with dairy cattle slurry (mixed in a ratio of 1:3; w.w.) was evaluated at 35 °C focusing on methane production and stabilization. Three pre-treatments were applied (1) digestion with no pre-treatment (control), (2) ultrasound, and (3) thermal hygienization (70 °C, 60 min). Methane production potentials (MPP) of the untreated, ultrasound pre-treated and hygienized feed mixtures were 300, 340, and 360 m(3) CH(4)/t volatile solids (VS) added, as determined in the batch experiments. However, the specific methane productions (SMP) achieved in reactor experiments (hydraulic retention time HRT 21 d, organic loading rate OLR 3.0±0.1 kg VS/m(3) d) were 11±2% (untreated and ultrasound pre-treated) and 22±3% (hygienized) lower than the potentials. Ultrasound with the energy input of 1000 kJ/kg total solids (TS) and hygienization of the ready-made feed were the most suitable pre-treatment modes studied.

Sand filters for removal of microbes and nutrients from wastewater during a one-year pilot study in a cold temperate climate

Onsite wastewater treatment systems (OWTS) are recognised as potential threats to groundwater or other water environments subject to discharged effluents. In this study, the microbiological and nutrient removal properties of three different pilot-scale sand filters (SFs) were followed over a one-year period. Moreover, a separate phosphorus removal unit was tested for six months. For the best treatment system, the average log removals were 2.2-3.5 for pathogenic human noro- and adenoviruses and 4.3-5.2 and 4.6-5.4 for indicator viruses and bacteria, respectively. The system that effectively removed microbes was also efficient at removing nutrients. However, the poorest treatment system yielded substantially lower removals. The remarkable differences noted between the studied SFs highlights the importance of construction materials and the careful planning of the filters. Moreover, seasonal conditions appear to have a clear effect on purification efficiencies, emphasising the vulnerability of these systems especially in cold climates.

Microbial Contamination of Groundwater at Small Community Water Supplies in Finland

The raw water quality and associations between the factors considered as threats to water safety were studied in 20 groundwater supplies in central Finland in 2002–2004. Faecal contaminations indicated by the appearance of Escherichia coli or intestinal enterococci were present in five small community water supplies, all these managed by local water cooperatives. Elevated concentrations of nutrients in raw water were linked with the presence of faecal bacteria. The presence of on-site technical hazards to water safety, such as inadequate well construction and maintenance enabling surface water to enter into the well and the insufficient depth of protective soil layers above the groundwater table, showed the vulnerability of the quality of groundwater used for drinking purposes. To minimize the risk of waterborne illnesses, the vulnerable water supplies need to be identified and appropriate prevention measures such as disinfection should be applied.

Mycorrhizal growth in pure cultures in the presence of pesticides.

The effects of pesticides on 64 ectomycorrhizal fungi of boreal forest trees were studied in vitro. The pesticides (fungicides: benomyl, chlorothalonil, copper oxychloride, maneb and propiconazole; herbicides: chlorthiamid, glyphosate, hexazinone, linuron and terbuthylazine; insecticide: cypermethrin) were selected as those commonly used in Nordic forest nurseries and afforestation sites. In general, the fungicides proved to be more toxic to ectomycorrhizal fungi than the herbicides and cypermethrin. The fungicides, chlorothalonil and propiconazole, had the clearest inhibitory effect on growth of mycorrhizal fungi. Conversely, maneb, glyphosate and terbuthylazine stimulated the growth of some mycorrhizal fungi. Leccinum versipelle and L. scabrum, Paxillus involutus and Cenococcum geophilum were the most sensitive ectomycorrhizal fungi to the various pesticides.

Fertilizer value of urine in pumpkin (Cucurbita maxima L.) cultivation.

Puhtaan virtsan lannoitearvoa tutkittiin kurpitsan kasvatuksessakayttamalla 113 kg typpea hehtaaria kohden. Verranteina olivat lannoittamatta jattaminen ja mineraalilannoittaminen. Virtsalannoitettuna kurpitsan varsisto kasvoi pidemmaksi kuin mineraalilannoitettuna tai lannoittamattomana. Kuitenkin mineraalilannoitus tuotti enemman satoa kuin virtsalannoitus tai lannoittamatta jattaminen. On mahdollista, etta virtsalannoitettuna kurpitsat karsivat kaliumin puutteesta, silla niihin kehittyi vahemman kukkia ja siten myos vahemman hedelmia kuin mineraalilannoitettuihin kurpitsoihin. Virtsalla lannoitetusta maasta saatiin kurpitsasatoa 17,2 tonnia hehtaarilta enemman kuin lannoittamattomasta maasta saatiin. Kaikilla tavoin lannoitettujen kurpitsamaiden sadon mikrobiologinen laatu oli moitteeton ja maku seka sokeri- ja valkuaisainepitoisuudet olivat yhtalaisia. Virstalannoitetuissa maissa kasvaneissa kurpitsoissa oli vahemman nitraattia, mutta enemman kloridia kuin mineraalilannoitetuissa tai lannoittamattomissa maissa kasvaneissa kurpitsoissa. Tutkimuksen mukaan virtsa kurpitsan kasvualustan lannoitteena ei aiheuta sadolle kemiallisia tai hygieenisia haittoja, ja virtsalannoitus tuottaa paremman sadon kuin lannoittamatta jattaminen. Kuitenkin mineraalilannoitus tuotti tutkimuksen verranteista suurimman sadon.