Effect of commercial mineral-based additives on composting and compost quality.
The effectiveness of two commercial additives meant to improve the composting process was studied in a laboratory-scale experiment. Improver A (sulphates and oxides of iron, magnesium, manganese, and zinc mixed with clay) and B (mixture of calcium hydroxide, peroxide, and oxide) were added to source-separated biowaste:peat mixture (1:1, v/v) in proportions recommended by the producers. The composting process (T, emissions of CO(2), NH(3), and CH(4)) and the quality of the compost (pH, conductivity, C/N ratio, water-soluble NH(4)-N and NO(3)-N, water- and NaOH-soluble low-weight carboxylic acids, nutrients, heavy metals and phytotoxicity to Lepidium sarivum) were monitored during one year. Compared with the control, the addition of improver B increased pH by two units, led to an earlier elimination of water-soluble ammonia, an increase in nitrates, a 10-fold increase in concentrations of acetic acid, and shortened phytotoxicity period by half; as negative aspect it led to volatilization of ammonia. The addition of improver A led to a longer thermophilic stage by one week and lower concentrations of low-weight carboxylic acids (both water- and NaOH-extractable) with formic and acetic of similar amounts, however, most of the aspects claimed by the improver's producer were not confirmed in this trial.
Himanen
M
M
Department of Biological and Environmental Sciences, University of Jyväskylä, PL 35, FIN 40014 Jyväskylä, Finland. marina.himanen@bytl.jyu.fi
Hänninen
K
K
D019342:Acetic Acid / Q000633:toxicity; D002244:Carbon / Q000032:analysis; D002264:Carboxylic Acids / Q000032:analysis; D004553:Electric Conductivity; D052918:Environmental Restoration and Remediation / Q000379:methods*; D005561:Formates / Q000633:toxicity; D005735:Garbage; D006863:Hydrogen-Ion Concentration; D029686:Lepidium / Q000187:drug effects; D019216:Metals, Heavy / Q000032:analysis; D008903:Minerals / Q000032:analysis*; D009584:Nitrogen / Q000032:analysis; D000644:Quaternary Ammonium Compounds / Q000032:analysis; D012987:Soil / Q000032:analysis; D012989:Soil Pollutants / Q000633:toxicity; D013696:Temperature; D018675:Toxicity Tests
D002264:Carboxylic Acids; D005561:Formates; D019216:Metals, Heavy; D008903:Minerals; D000644:Quaternary Ammonium Compounds; D012987:Soil; D012989:Soil Pollutants; C030544:formic acid; D002244:Carbon; D009584:Nitrogen; D019342:Acetic Acid